注释代码

DateTimePickerDialog.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */           /*版权和许可证声明，说明了该文件的版权信息以及遵循的许可协议*/ 
+
+package net.micode.notes.ui;
+
+import java.util.Calendar;
+
+import net.micode.notes.R;
+import net.micode.notes.ui.DateTimePicker;
+import net.micode.notes.ui.DateTimePicker.OnDateTimeChangedListener;
+
+import android.app.AlertDialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.DialogInterface.OnClickListener;
+import android.text.format.DateFormat;
+import android.text.format.DateUtils;       /*设置了代码的包名，并导入了所需的类和接口*/
+
+public class DateTimePickerDialog extends AlertDialog implements OnClickListener {   /*定义了一个名为 DateTimePickerDialog 的公共类，它扩展了 AlertDialog 并实现了 OnClickListener 接口。*/
+
+    private Calendar mDate = Calendar.getInstance();
+    private boolean mIs24HourView;
+    private OnDateTimeSetListener mOnDateTimeSetListener;
+    private DateTimePicker mDateTimePicker;  /*声明了一些私有变量，用于存储日期时间信息、24小时格式标志、监听器和日期时间选择器。 */
+
+    public interface OnDateTimeSetListener {
+        void OnDateTimeSet(AlertDialog dialog, long date);
+    }     /*定义了一个内部接口 OnDateTimeSetListener，用于接收日期时间设置事件的回调。 */
+
+    public DateTimePickerDialog(Context context, long date) {
+        super(context);   /*构造函数初始化父类 AlertDialog */
+        mDateTimePicker = new DateTimePicker(context);
+        setView(mDateTimePicker);/*创建一个 DateTimePicker 实例并设置为对话框的内容视图*/
+        mDateTimePicker.setOnDateTimeChangedListener(new OnDateTimeChangedListener() {
+            public void onDateTimeChanged(DateTimePicker view, int year, int month,
+                    int dayOfMonth, int hourOfDay, int minute) {
+                mDate.set(Calendar.YEAR, year);
+                mDate.set(Calendar.MONTH, month);
+                mDate.set(Calendar.DAY_OF_MONTH, dayOfMonth);
+                mDate.set(Calendar.HOUR_OF_DAY, hourOfDay);
+                mDate.set(Calendar.MINUTE, minute);
+                updateTitle(mDate.getTimeInMillis());
+            }
+        });/*为 DateTimePicker 设置监听器，在日期时间改变时更新内部的日历对象，并调用 updateTitle 方法更新对话框标题 */
+        mDate.setTimeInMillis(date);
+        mDate.set(Calendar.SECOND, 0);
+        mDateTimePicker.setCurrentDate(mDate.getTimeInMillis());
+        setButton(context.getString(R.string.datetime_dialog_ok), this);
+        setButton2(context.getString(R.string.datetime_dialog_cancel), (OnClickListener)null);
+        set24HourView(DateFormat.is24HourFormat(this.getContext()));
+        updateTitle(mDate.getTimeInMillis());
+    }   /*初始化日期时间对象，并设置到 DateTimePicker 中。设置对话框的确认和取消按钮，并根据系统设置决定是否使用24小时制显示时间。最后更新对话框标题。 */
+
+    public void set24HourView(boolean is24HourView) {
+        mIs24HourView = is24HourView;
+    }    /*设置是否使用24小时制显示时间的方法*/
+
+    public void setOnDateTimeSetListener(OnDateTimeSetListener callBack) {
+        mOnDateTimeSetListener = callBack;
+    }    /*设置监听器的方法*/
+
+    private void updateTitle(long date) {
+        int flag =
+            DateUtils.FORMAT_SHOW_YEAR |
+            DateUtils.FORMAT_SHOW_DATE |
+            DateUtils.FORMAT_SHOW_TIME;
+        flag |= mIs24HourView ? DateUtils.FORMAT_24HOUR : DateUtils.FORMAT_24HOUR;
+        setTitle(DateUtils.formatDateTime(this.getContext(), date, flag));
+    }   /*更新对话框标题的方法，根据当前日期时间和格式化标志来显示日期时间。*/
+
+    public void onClick(DialogInterface arg0, int arg1) {
+        if (mOnDateTimeSetListener != null) {
+            mOnDateTimeSetListener.OnDateTimeSet(this, mDate.getTimeInMillis());
+        }
+    }/*实现 OnClickListener 接口的 onClick 方法，当点击对话框上的按钮时，如果设置了监听器，则调用其 OnDateTimeSet 方法*/
+
+}/*类定义结束*/

DropdownMenu.java

@@ -0,0 +1,70 @@
+
+
+/*这段代码展示了如何在 Android 应用程序中实现一个带有弹出菜单的下拉按钮。
+这个 DropdownMenu 类封装了创建一个带有菜单的按钮所需的所有步骤。 */
+
+
+
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;
+
+import android.content.Context;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.widget.Button;
+import android.widget.PopupMenu;
+import android.widget.PopupMenu.OnMenuItemClickListener;
+
+import net.micode.notes.R;
+
+public class DropdownMenu {  /*定义了一个名为 DropdownMenu 的公共类*/
+    private Button mButton;
+    private PopupMenu mPopupMenu;
+    private Menu mMenu;   /*声明了一些私有变量，分别代表按钮、弹出菜单和菜单对象。*/
+
+    public DropdownMenu(Context context, Button button, int menuId) {
+        mButton = button;
+        mButton.setBackgroundResource(R.drawable.dropdown_icon);  /*构造函数初始化成员变量，设置按钮的背景图片*/
+        mPopupMenu = new PopupMenu(context, mButton);
+        mMenu = mPopupMenu.getMenu();
+        mPopupMenu.getMenuInflater().inflate(menuId, mMenu);/*创建 PopupMenu 实例，获取菜单对象，并通过提供的菜单资源 ID 充气菜单*/
+        mButton.setOnClickListener(new OnClickListener() {
+            public void onClick(View v) {
+                mPopupMenu.show();
+            }
+        });
+    }    /*为按钮设置点击监听器，点击时显示弹出菜单*/
+
+    public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
+        if (mPopupMenu != null) {
+            mPopupMenu.setOnMenuItemClickListener(listener);
+        }
+    }   /*设置弹出菜单项点击监听器的方法，允许外部设置监听器以便处理菜单项点击事件*/
+
+    public MenuItem findItem(int id) {
+        return mMenu.findItem(id);
+    }   /*提供一个方法用于根据资源 ID 查找菜单项*/
+
+    public void setTitle(CharSequence title) {
+        mButton.setText(title);
+    }/*设置按钮文本的方法*/
+}
+  
+  /*这个 DropdownMenu 类使得在应用程序中添加带有弹出菜单的按钮变得更加容易，通过构造函数传入上下文、按钮和菜单资源 ID，就可以轻松地创建和使用带有菜单的按钮。*/

FoldersListAdapter.java

@@ -0,0 +1,87 @@
+
+
+/*这段代码定义了一个名为 FoldersListAdapter 的类，它是 CursorAdapter 的子类，
+主要用于适配数据库查询结果（通过 Cursor 对象表示），并将数据绑定到列表项视图上。
+此适配器特别适用于展示文件夹列表，每个文件夹项包含一个名称。*/
+
+
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;  /*定义了代码所在的包名*/
+
+import android.content.Context;
+import android.database.Cursor;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.CursorAdapter;
+import android.widget.LinearLayout;
+import android.widget.TextView;   /*导入了所需的类和接口*/
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.NoteColumns;   /*导入了应用相关的资源和数据模型类*/
+
+
+public class FoldersListAdapter extends CursorAdapter {  /*定义了一个名为 FoldersListAdapter 的公共类，继承自 CursorAdapter*/
+    public static final String [] PROJECTION = {
+        NoteColumns.ID,
+        NoteColumns.SNIPPET
+    };     /*定义了数据库查询的列名数组*/
+
+    public static final int ID_COLUMN   = 0;
+    public static final int NAME_COLUMN = 1;   /*定义了查询结果中每列的索引*/
+
+    public FoldersListAdapter(Context context, Cursor c) {
+        super(context, c);    /*构造函数，初始化父类 CursorAdapter*/
+        // TODO Auto-generated constructor stub
+    }
+
+    @Override
+    public View newView(Context context, Cursor cursor, ViewGroup parent) {
+        return new FolderListItem(context);
+    }    /*覆盖 newView 方法，返回一个新的视图实例，这里返回的是一个 FolderListItem 实例*/
+
+    @Override
+    public void bindView(View view, Context context, Cursor cursor) {
+        if (view instanceof FolderListItem) {
+            String folderName = (cursor.getLong(ID_COLUMN) == Notes.ID_ROOT_FOLDER) ? context
+                    .getString(R.string.menu_move_parent_folder) : cursor.getString(NAME_COLUMN);
+            ((FolderListItem) view).bind(folderName);
+        }
+    }    /*覆盖 bindView 方法，将数据绑定到视图上。如果是根目录，则使用特定字符串，否则从 Cursor 中获取名称*/
+
+    public String getFolderName(Context context, int position) {
+        Cursor cursor = (Cursor) getItem(position);
+        return (cursor.getLong(ID_COLUMN) == Notes.ID_ROOT_FOLDER) ? context
+                .getString(R.string.menu_move_parent_folder) : cursor.getString(NAME_COLUMN);
+    }      /*提供了一个方法用于根据位置获取文件夹名称*/
+
+    private class FolderListItem extends LinearLayout {
+        private TextView mName;
+
+        public FolderListItem(Context context) {
+            super(context);
+            inflate(context, R.layout.folder_list_item, this);
+            mName = (TextView) findViewById(R.id.tv_folder_name);
+        }
+
+        public void bind(String name) {
+            mName.setText(name);
+        }
+    }   /*定义了一个内部类 FolderListItem，它是一个 LinearLayout 的子类，用于表示一个文件夹列表项，并提供了绑定数据的方法*/
+
+}

NoteEditActivity.java

@@ -0,0 +1,999 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;
+
+/*导入的包*/
+import android.app.Activity;
+import android.app.AlarmManager;
+import android.app.AlertDialog;
+import android.app.PendingIntent;
+import android.app.SearchManager;
+import android.appwidget.AppWidgetManager;
+import android.content.ContentUris;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.graphics.Paint;
+import android.os.Bundle;
+import android.preference.PreferenceManager;
+import android.text.Spannable;
+import android.text.SpannableString;
+import android.text.TextUtils;
+import android.text.format.DateUtils;
+import android.text.style.BackgroundColorSpan;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.view.WindowManager;
+import android.widget.CheckBox;
+import android.widget.CompoundButton;
+import android.widget.CompoundButton.OnCheckedChangeListener;
+import android.widget.EditText;
+import android.widget.ImageView;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.TextNote;
+import net.micode.notes.model.WorkingNote;
+import net.micode.notes.model.WorkingNote.NoteSettingChangedListener;
+import net.micode.notes.tool.DataUtils;
+import net.micode.notes.tool.ResourceParser;
+import net.micode.notes.tool.ResourceParser.TextAppearanceResources;
+import net.micode.notes.ui.DateTimePickerDialog.OnDateTimeSetListener;
+import net.micode.notes.ui.NoteEditText.OnTextViewChangeListener;
+import net.micode.notes.widget.NoteWidgetProvider_2x;
+import net.micode.notes.widget.NoteWidgetProvider_4x;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+
+public class NoteEditActivity extends Activity implements OnClickListener,/*类定义*/
+        NoteSettingChangedListener, OnTextViewChangeListener {   /*NoteEditActivity继承自Activity，实现了OnClickListener、NoteSettingChangedListener、OnTextViewChangeListener接口*/
+    private class HeadViewHolder {   /*内部类HeadViewHolder用于持有头部试图组件*/
+        public TextView tvModified;
+
+        public ImageView ivAlertIcon;
+
+        public TextView tvAlertDate;
+
+        public ImageView ibSetBgColor;
+    }
+
+    private static final Map<Integer, Integer> sBgSelectorBtnsMap = new HashMap<Integer, Integer>();/*静态成员变量  sBgSelectorBtnsMap：背景颜色按钮与其对应的颜色资源ID的映射*/
+    static {
+        sBgSelectorBtnsMap.put(R.id.iv_bg_yellow, ResourceParser.YELLOW);
+        sBgSelectorBtnsMap.put(R.id.iv_bg_red, ResourceParser.RED);
+        sBgSelectorBtnsMap.put(R.id.iv_bg_blue, ResourceParser.BLUE);
+        sBgSelectorBtnsMap.put(R.id.iv_bg_green, ResourceParser.GREEN);
+        sBgSelectorBtnsMap.put(R.id.iv_bg_white, ResourceParser.WHITE);
+    }
+
+    private static final Map<Integer, Integer> sBgSelectorSelectionMap = new HashMap<Integer, Integer>();/*sBgSelectorSelectionMap：文字外观资源ID 与其对应的选中图表资源ID的放映*/
+    static {
+        sBgSelectorSelectionMap.put(ResourceParser.YELLOW, R.id.iv_bg_yellow_select);
+        sBgSelectorSelectionMap.put(ResourceParser.RED, R.id.iv_bg_red_select);
+        sBgSelectorSelectionMap.put(ResourceParser.BLUE, R.id.iv_bg_blue_select);
+        sBgSelectorSelectionMap.put(ResourceParser.GREEN, R.id.iv_bg_green_select);
+        sBgSelectorSelectionMap.put(ResourceParser.WHITE, R.id.iv_bg_white_select);
+    }
+
+    private static final Map<Integer, Integer> sFontSizeBtnsMap = new HashMap<Integer, Integer>();
+    static {
+        sFontSizeBtnsMap.put(R.id.ll_font_large, ResourceParser.TEXT_LARGE);
+        sFontSizeBtnsMap.put(R.id.ll_font_small, ResourceParser.TEXT_SMALL);
+        sFontSizeBtnsMap.put(R.id.ll_font_normal, ResourceParser.TEXT_MEDIUM);
+        sFontSizeBtnsMap.put(R.id.ll_font_super, ResourceParser.TEXT_SUPER);
+    }
+
+    private static final Map<Integer, Integer> sFontSelectorSelectionMap = new HashMap<Integer, Integer>();
+    static {
+        sFontSelectorSelectionMap.put(ResourceParser.TEXT_LARGE, R.id.iv_large_select);
+        sFontSelectorSelectionMap.put(ResourceParser.TEXT_SMALL, R.id.iv_small_select);
+        sFontSelectorSelectionMap.put(ResourceParser.TEXT_MEDIUM, R.id.iv_medium_select);
+        sFontSelectorSelectionMap.put(ResourceParser.TEXT_SUPER, R.id.iv_super_select);
+    }
+
+    private static final String TAG = "NoteEditActivity";/*成员变量*/
+
+    private HeadViewHolder mNoteHeaderHolder;
+
+    private View mHeadViewPanel;
+
+    private View mNoteBgColorSelector;
+
+    private View mFontSizeSelector;
+
+    private EditText mNoteEditor;
+
+    private View mNoteEditorPanel;
+
+    private WorkingNote mWorkingNote;
+
+    private SharedPreferences mSharedPrefs;
+    private int mFontSizeId;
+
+    private static final String PREFERENCE_FONT_SIZE = "pref_font_size";
+
+    private static final int SHORTCUT_ICON_TITLE_MAX_LEN = 10;
+
+    public static final String TAG_CHECKED = String.valueOf('\u221A');
+    public static final String TAG_UNCHECKED = String.valueOf('\u25A1');
+
+    private LinearLayout mEditTextList;
+
+    private String mUserQuery;
+    private Pattern mPattern;
+
+/*- `TAG`：日志标签。
+- `mNoteHeaderHolder`：头部视图持有者。
+- `mHeadViewPanel`：头部视图面板。
+- `mNoteBgColorSelector`：背景颜色选择器。
+- `mFontSizeSelector`：字体大小选择器。
+- `mNoteEditor`：编辑文本框。
+- `mNoteEditorPanel`：编辑面板。
+- `mWorkingNote`：当前编辑的笔记。
+- `mSharedPrefs`：共享偏好设置。
+- `mFontSizeId`：当前字体大小ID。
+- `PREFERENCE_FONT_SIZE`：字体大小偏好键。
+- `SHORTCUT_ICON_TITLE_MAX_LEN`：快捷方式标题最大长度。
+- `TAG_CHECKED` 和 `TAG_UNCHECKED`：复选框标记。
+- `mEditTextList`：编辑列表。
+- `mUserQuery`：用户查询字符串。
+- `mPattern`：正则表达式模式。
+*/
+
+    @Override   
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        this.setContentView(R.layout.note_edit);/*重写了 onCreate() 方法，这是 Activity 生命周期的第一个回调方法。首先调用了父类的 onCreate() 方法，并设置布局文件 R.layout.note_edit 作为 Activity 的视图*/
+
+        if (savedInstanceState == null && !initActivityState(getIntent())) {
+            finish();
+            return;/*检查是否有保存的状态，如果没有并且初始化活动状态失败，则关闭当前 Activity。*/
+        }
+        initResources();
+    }    /*调用 initResources() 方法，可能是用来初始化一些资源，例如 UI 组件等*/
+
+    /**
+     * Current activity may be killed when the memory is low. Once it is killed, for another time
+     * user load this activity, we should restore the former state
+     */
+    @Override
+    protected void onRestoreInstanceState(Bundle savedInstanceState) {
+        super.onRestoreInstanceState(savedInstanceState);/*重写了 onRestoreInstanceState() 方法，这是在 Activity 被重新启动并且有之前保存的状态时被调用的方法。同样先调用了父类的相应方法*/
+        if (savedInstanceState != null && savedInstanceState.containsKey(Intent.EXTRA_UID)) {
+            Intent intent = new Intent(Intent.ACTION_VIEW);
+            intent.putExtra(Intent.EXTRA_UID, savedInstanceState.getLong(Intent.EXTRA_UID));
+            if (!initActivityState(intent)) {
+                finish();
+                return;
+            }
+            Log.d(TAG, "Restoring from killed activity");
+        }
+    }   /*检查是否有保存的状态并且包含 Intent.EXTRA_UID 键，如果有则恢复之前的 Activity 状态，使用 initActivityState() 方法初始化，并记录日志信息*/
+
+    private boolean initActivityState(Intent intent) {   /*定义了一个私有方法 initActivityState() 用于根据意图（Intent）初始化 Activity 的状态。*/
+        /**
+         * If the user specified the {@link Intent#ACTION_VIEW} but not provided with id,
+         * then jump to the NotesListActivity
+         */
+        mWorkingNote = null;
+        if (TextUtils.equals(Intent.ACTION_VIEW, intent.getAction())) {
+            long noteId = intent.getLongExtra(Intent.EXTRA_UID, 0);
+            mUserQuery = "";   /*初始化 mWorkingNote 为空，并检查意图的动作是否为 Intent.ACTION_VIEW，如果是，则获取笔记的 ID*/
+
+            /**
+             * Starting from the searched result
+             */
+            if (intent.hasExtra(SearchManager.EXTRA_DATA_KEY)) {
+                noteId = Long.parseLong(intent.getStringExtra(SearchManager.EXTRA_DATA_KEY));
+                mUserQuery = intent.getStringExtra(SearchManager.USER_QUERY);
+            }  /*如果意图包含搜索管理器的额外数据键，则从中提取笔记 ID 和用户的查询。*/
+
+            if (!DataUtils.visibleInNoteDatabase(getContentResolver(), noteId, Notes.TYPE_NOTE)) {
+                Intent jump = new Intent(this, NotesListActivity.class);
+                startActivity(jump);
+                showToast(R.string.error_note_not_exist);
+                finish();
+                return false;
+            } else {
+                mWorkingNote = WorkingNote.load(this, noteId);
+                if (mWorkingNote == null) {
+                    Log.e(TAG, "load note failed with note id" + noteId);
+                    finish();
+                    return false;
+                }
+            }   /*检查笔记是否存在于数据库中，如果不存在则跳转到笔记列表活动，并显示错误信息。如果存在，则加载笔记。*/
+            getWindow().setSoftInputMode(
+                    WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN
+                            | WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);  /*设置软键盘模式为隐藏且调整窗口大小。*/
+        } else if(TextUtils.equals(Intent.ACTION_INSERT_OR_EDIT, intent.getAction())) {
+            // New note
+            long folderId = intent.getLongExtra(Notes.INTENT_EXTRA_FOLDER_ID, 0);
+            int widgetId = intent.getIntExtra(Notes.INTENT_EXTRA_WIDGET_ID,
+                    AppWidgetManager.INVALID_APPWIDGET_ID);
+            int widgetType = intent.getIntExtra(Notes.INTENT_EXTRA_WIDGET_TYPE,
+                    Notes.TYPE_WIDGET_INVALIDE);
+            int bgResId = intent.getIntExtra(Notes.INTENT_EXTRA_BACKGROUND_ID,
+                    ResourceParser.getDefaultBgId(this));   /*如果意图动作为 Intent.ACTION_INSERT_OR_EDIT，则获取相关参数，如文件夹 ID、小部件 ID 等*/
+
+            // Parse call-record note
+            String phoneNumber = intent.getStringExtra(Intent.EXTRA_PHONE_NUMBER);
+            long callDate = intent.getLongExtra(Notes.INTENT_EXTRA_CALL_DATE, 0);
+            if (callDate != 0 && phoneNumber != null) {
+                if (TextUtils.isEmpty(phoneNumber)) {
+                    Log.w(TAG, "The call record number is null");
+                }
+                long noteId = 0;
+                if ((noteId = DataUtils.getNoteIdByPhoneNumberAndCallDate(getContentResolver(),
+                        phoneNumber, callDate)) > 0) {
+                    mWorkingNote = WorkingNote.load(this, noteId);
+                    if (mWorkingNote == null) {
+                        Log.e(TAG, "load call note failed with note id" + noteId);
+                        finish();
+                        return false;
+                    }
+                } else {
+                    mWorkingNote = WorkingNote.createEmptyNote(this, folderId, widgetId,
+                            widgetType, bgResId);
+                    mWorkingNote.convertToCallNote(phoneNumber, callDate);
+                }
+            } else {
+                mWorkingNote = WorkingNote.createEmptyNote(this, folderId, widgetId, widgetType,
+                        bgResId);
+            }     /*如果意图携带了电话号码和通话日期，则加载或创建一个与通话记录相关的笔记。*/
+
+            getWindow().setSoftInputMode(
+                    WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE
+                            | WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE);   /*设置软键盘模式为调整窗口大小并且可见。*/
+        } else {
+            Log.e(TAG, "Intent not specified action, should not support");
+            finish();
+            return false;
+        }     /*如果意图没有指定支持的动作，则记录错误日志并关闭 Activity。*/
+        mWorkingNote.setOnSettingStatusChangedListener(this);
+        return true;
+    }    /*设置 mWorkingNote 的状态改变监听器，并返回 true 表示初始化成功。*/
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+        initNoteScreen();
+    }     /*重写 onResume() 方法，在 Activity 可见时调用父类的 onResume() 并初始化笔记屏幕。*/
+
+    private void initNoteScreen() {
+        mNoteEditor.setTextAppearance(this, TextAppearanceResources
+                .getTexAppearanceResource(mFontSizeId));
+        if (mWorkingNote.getCheckListMode() == TextNote.MODE_CHECK_LIST) {
+            switchToListMode(mWorkingNote.getContent());
+        } else {
+            mNoteEditor.setText(getHighlightQueryResult(mWorkingNote.getContent(), mUserQuery));
+            mNoteEditor.setSelection(mNoteEditor.getText().length());
+        }     /*定义 initNoteScreen() 方法，初始化笔记编辑器的文本外观，并根据笔记的工作模式来设置编辑器内容。*/
+        for (Integer id : sBgSelectorSelectionMap.keySet()) {
+            findViewById(sBgSelectorSelectionMap.get(id)).setVisibility(View.GONE);
+        }
+        mHeadViewPanel.setBackgroundResource(mWorkingNote.getTitleBgResId());
+        mNoteEditorPanel.setBackgroundResource(mWorkingNote.getBgColorResId());    /*隐藏背景选择器，并设置标题面板和笔记编辑面板的背景色。*/
+
+        mNoteHeaderHolder.tvModified.setText(DateUtils.formatDateTime(this,
+                mWorkingNote.getModifiedDate(), DateUtils.FORMAT_SHOW_DATE
+                        | DateUtils.FORMAT_NUMERIC_DATE | DateUtils.FORMAT_SHOW_TIME
+                        | DateUtils.FORMAT_SHOW_YEAR));   /*设置修改日期的文本格式。*/
+
+        /**
+         * TODO: Add the menu for setting alert. Currently disable it because the DateTimePicker
+         * is not ready
+         */
+        showAlertHeader();
+    }    /*预留了一个待完成的任务，用于设置提醒功能，并调用 showAlertHeader() 显示或隐藏提醒信息。*/
+
+    private void showAlertHeader() {
+        if (mWorkingNote.hasClockAlert()) {
+            long time = System.currentTimeMillis();
+            if (time > mWorkingNote.getAlertDate()) {
+                mNoteHeaderHolder.tvAlertDate.setText(R.string.note_alert_expired);
+            } else {
+                mNoteHeaderHolder.tvAlertDate.setText(DateUtils.getRelativeTimeSpanString(
+                        mWorkingNote.getAlertDate(), time, DateUtils.MINUTE_IN_MILLIS));
+            }
+            mNoteHeaderHolder.tvAlertDate.setVisibility(View.VISIBLE);
+            mNoteHeaderHolder.ivAlertIcon.setVisibility(View.VISIBLE);
+        } else {
+            mNoteHeaderHolder.tvAlertDate.setVisibility(View.GONE);
+            mNoteHeaderHolder.ivAlertIcon.setVisibility(View.GONE);
+        };
+    }    /*定义 showAlertHeader() 方法，根据笔记是否有提醒来显示或隐藏提醒信息。*/
+
+    @Override
+    protected void onNewIntent(Intent intent) {
+        super.onNewIntent(intent);
+        initActivityState(intent);
+    }          /*重写 onNewIntent() 方法，在接收到新意图时初始化活动状态。*/
+
+    @Override
+    protected void onSaveInstanceState(Bundle outState) {
+        super.onSaveInstanceState(outState);
+        /**
+         * For new note without note id, we should firstly save it to
+         * generate a id. If the editing note is not worth saving, there
+         * is no id which is equivalent to create new note
+         */
+        if (!mWorkingNote.existInDatabase()) {
+            saveNote();
+        }
+        outState.putLong(Intent.EXTRA_UID, mWorkingNote.getNoteId());
+        Log.d(TAG, "Save working note id: " + mWorkingNote.getNoteId() + " onSaveInstanceState");
+    }       /*重写 onSaveInstanceState() 方法，在 Activity 需要保存其状态时确保笔记已保存，并存储笔记 ID 到 Bundle 中。*/
+
+    @Override
+    public boolean dispatchTouchEvent(MotionEvent ev) {
+        if (mNoteBgColorSelector.getVisibility() == View.VISIBLE
+                && !inRangeOfView(mNoteBgColorSelector, ev)) {
+            mNoteBgColorSelector.setVisibility(View.GONE);
+            return true;
+        }
+
+        if (mFontSizeSelector.getVisibility() == View.VISIBLE
+                && !inRangeOfView(mFontSizeSelector, ev)) {
+            mFontSizeSelector.setVisibility(View.GONE);
+            return true;
+        }
+        return super.dispatchTouchEvent(ev);
+    }     /*重写 dispatchTouchEvent() 方法，处理触摸事件，当触摸不在选择器范围内时隐藏它们。*/
+
+    private boolean inRangeOfView(View view, MotionEvent ev) {
+        int []location = new int[2];
+        view.getLocationOnScreen(location);
+        int x = location[0];
+        int y = location[1];
+        if (ev.getX() < x
+                || ev.getX() > (x + view.getWidth())
+                || ev.getY() < y
+                || ev.getY() > (y + view.getHeight())) {
+                    return false;
+                }
+        return true;
+    }    /*定义 inRangeOfView() 方法，判断触摸事件是否发生在给定视图的范围内。*/
+
+    private void initResources() {
+        mHeadViewPanel = findViewById(R.id.note_title);
+        mNoteHeaderHolder = new HeadViewHolder();
+        mNoteHeaderHolder.tvModified = (TextView) findViewById(R.id.tv_modified_date);
+        mNoteHeaderHolder.ivAlertIcon = (ImageView) findViewById(R.id.iv_alert_icon);
+        mNoteHeaderHolder.tvAlertDate = (TextView) findViewById(R.id.tv_alert_date);
+        mNoteHeaderHolder.ibSetBgColor = (ImageView) findViewById(R.id.btn_set_bg_color);
+        mNoteHeaderHolder.ibSetBgColor.setOnClickListener(this);
+        mNoteEditor = (EditText) findViewById(R.id.note_edit_view);
+        mNoteEditorPanel = findViewById(R.id.sv_note_edit);
+        mNoteBgColorSelector = findViewById(R.id.note_bg_color_selector);
+        for (int id : sBgSelectorBtnsMap.keySet()) {
+            ImageView iv = (ImageView) findViewById(id);
+            iv.setOnClickListener(this);
+        }
+
+        mFontSizeSelector = findViewById(R.id.font_size_selector);
+        for (int id : sFontSizeBtnsMap.keySet()) {
+            View view = findViewById(id);
+            view.setOnClickListener(this);
+        };
+        mSharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
+        mFontSizeId = mSharedPrefs.getInt(PREFERENCE_FONT_SIZE, ResourceParser.BG_DEFAULT_FONT_SIZE);
+        /**
+         * HACKME: Fix bug of store the resource id in shared preference.
+         * The id may larger than the length of resources, in this case,
+         * return the {@link ResourceParser#BG_DEFAULT_FONT_SIZE}
+         */
+        if(mFontSizeId >= TextAppearanceResources.getResourcesSize()) {
+            mFontSizeId = ResourceParser.BG_DEFAULT_FONT_SIZE;
+        }
+        mEditTextList = (LinearLayout) findViewById(R.id.note_edit_list);
+    }    /*定义 initResources() 方法，初始化各种 UI 组件，并设置监听器。*/
+
+    @Override
+    protected void onPause() {
+        super.onPause();
+        if(saveNote()) {
+            Log.d(TAG, "Note data was saved with length:" + mWorkingNote.getContent().length());
+        }
+        clearSettingState();
+    }      /*重写 onPause() 方法，在 Activity 暂停时保存笔记数据，并清除设置状态。*/
+
+    private void updateWidget() {
+        Intent intent = new Intent(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
+        if (mWorkingNote.getWidgetType() == Notes.TYPE_WIDGET_2X) {
+            intent.setClass(this, NoteWidgetProvider_2x.class);
+        } else if (mWorkingNote.getWidgetType() == Notes.TYPE_WIDGET_4X) {
+            intent.setClass(this, NoteWidgetProvider_4x.class);
+        } else {
+            Log.e(TAG, "Unspported widget type");
+            return;
+        }
+
+        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, new int[] {
+            mWorkingNote.getWidgetId()
+        });
+
+        sendBroadcast(intent);
+        setResult(RESULT_OK, intent);
+    }   /*定义 updateWidget() 方法，更新与笔记关联的小部件。*/
+
+/*方法*/
+/*onClick()*/
+    public void onClick(View v) {
+        int id = v.getId();
+        if (id == R.id.btn_set_bg_color) {
+            mNoteBgColorSelector.setVisibility(View.VISIBLE);
+            findViewById(sBgSelectorSelectionMap.get(mWorkingNote.getBgColorId())).setVisibility(
+                    -                    View.VISIBLE);
+        } else if (sBgSelectorBtnsMap.containsKey(id)) {
+            findViewById(sBgSelectorSelectionMap.get(mWorkingNote.getBgColorId())).setVisibility(
+                    View.GONE);
+            mWorkingNote.setBgColorId(sBgSelectorBtnsMap.get(id));
+            mNoteBgColorSelector.setVisibility(View.GONE);
+        } else if (sFontSizeBtnsMap.containsKey(id)) {
+            findViewById(sFontSelectorSelectionMap.get(mFontSizeId)).setVisibility(View.GONE);
+            mFontSizeId = sFontSizeBtnsMap.get(id);
+            mSharedPrefs.edit().putInt(PREFERENCE_FONT_SIZE, mFontSizeId).commit();
+            findViewById(sFontSelectorSelectionMap.get(mFontSizeId)).setVisibility(View.VISIBLE);
+            if (mWorkingNote.getCheckListMode() == TextNote.MODE_CHECK_LIST) {
+                getWorkingText();
+                switchToListMode(mWorkingNote.getContent());
+            } else {
+                mNoteEditor.setTextAppearance(this,
+                        TextAppearanceResources.getTexAppearanceResource(mFontSizeId));
+            }
+            mFontSizeSelector.setVisibility(View.GONE);
+        }
+    }
+
+/*onClick()`：处理点击事件。
+  - 如果点击的是背景颜色选择按钮，显示背景颜色选择器。
+  - 如果点击的是某个背景颜色按钮，更新笔记的背景颜色并隐藏选择器。
+  - 如果点击的是某个字体大小按钮，更新字体大小并隐藏选择器。
+  */
+
+
+ /*onBackPressed()*/
+    @Override
+    public void onBackPressed() {
+        if(clearSettingState()) {
+            return;
+        }
+
+        saveNote();
+        super.onBackPressed();
+    }     /*重写 onBackPressed() 方法，当用户按下返回键时：
+            首先尝试清除设置状态，如果成功则直接返回；
+            如果清除设置状态未执行，则保存当前笔记，并调用父类的 onBackPressed() 方法来处理返回键。*/
+
+    private boolean clearSettingState() {
+        if (mNoteBgColorSelector.getVisibility() == View.VISIBLE) {
+            mNoteBgColorSelector.setVisibility(View.GONE);
+            return true;
+        } else if (mFontSizeSelector.getVisibility() == View.VISIBLE) {
+            mFontSizeSelector.setVisibility(View.GONE);
+            return true;
+        }
+        return false;
+    }    /*定义 clearSettingState() 方法，用于隐藏笔记背景颜色选择器或字体大小选择器，并返回是否隐藏了某个选择器。*/
+
+    public void onBackgroundColorChanged() {
+        findViewById(sBgSelectorSelectionMap.get(mWorkingNote.getBgColorId())).setVisibility(
+                View.VISIBLE);
+        mNoteEditorPanel.setBackgroundResource(mWorkingNote.getBgColorResId());
+        mHeadViewPanel.setBackgroundResource(mWorkingNote.getTitleBgResId());
+    }   /*定义 onBackgroundColorChanged() 方法，当背景颜色改变时：
+          显示相应的背景颜色选择项；
+          设置笔记编辑面板和标题面板的新背景色。*/
+
+    @Override
+    public boolean onPrepareOptionsMenu(Menu menu) {
+        if (isFinishing()) {
+            return true;
+        }
+        clearSettingState();
+        menu.clear();
+        if (mWorkingNote.getFolderId() == Notes.ID_CALL_RECORD_FOLDER) {
+            getMenuInflater().inflate(R.menu.call_note_edit, menu);
+        } else {
+            getMenuInflater().inflate(R.menu.note_edit, menu);
+        }
+        if (mWorkingNote.getCheckListMode() == TextNote.MODE_CHECK_LIST) {
+            menu.findItem(R.id.menu_list_mode).setTitle(R.string.menu_normal_mode);
+        } else {
+            menu.findItem(R.id.menu_list_mode).setTitle(R.string.menu_list_mode);
+        }
+        if (mWorkingNote.hasClockAlert()) {
+            menu.findItem(R.id.menu_alert).setVisible(false);
+        } else {
+            menu.findItem(R.id.menu_delete_remind).setVisible(false);
+        }
+        return true;
+    }     /*重写 onPrepareOptionsMenu() 方法，当需要准备选项菜单时：
+            清除设置状态；
+            根据笔记所在的文件夹类型，加载不同的菜单资源；
+            根据笔记是否处于检查列表模式，改变相关菜单项的标题；
+            根据笔记是否有提醒，设置相关菜单项的可见性。*/
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        switch (item.getItemId()) {
+            case R.id.menu_new_note:
+                createNewNote();
+                break;
+            case R.id.menu_delete:
+                AlertDialog.Builder builder = new AlertDialog.Builder(this);
+                builder.setTitle(getString(R.string.alert_title_delete));
+                builder.setIcon(android.R.drawable.ic_dialog_alert);
+                builder.setMessage(getString(R.string.alert_message_delete_note));
+                builder.setPositiveButton(android.R.string.ok,
+                        new DialogInterface.OnClickListener() {
+                            public void onClick(DialogInterface dialog, int which) {
+                                deleteCurrentNote();
+                                finish();
+                            }
+                        });
+                builder.setNegativeButton(android.R.string.cancel, null);
+                builder.show();
+                break;
+            case R.id.menu_font_size:
+                mFontSizeSelector.setVisibility(View.VISIBLE);
+                findViewById(sFontSelectorSelectionMap.get(mFontSizeId)).setVisibility(View.VISIBLE);
+                break;
+            case R.id.menu_list_mode:
+                mWorkingNote.setCheckListMode(mWorkingNote.getCheckListMode() == 0 ?
+                        TextNote.MODE_CHECK_LIST : 0);
+                break;
+            case R.id.menu_share:
+                getWorkingText();
+                sendTo(this, mWorkingNote.getContent());
+                break;
+            case R.id.menu_send_to_desktop:
+                sendToDesktop();
+                break;
+            case R.id.menu_alert:
+                setReminder();
+                break;
+            case R.id.menu_delete_remind:
+                mWorkingNote.setAlertDate(0, false);
+                break;
+            default:
+                break;
+        }
+        return true;
+    }
+    /*重写 onOptionsItemSelected() 方法，当用户选择菜单项时：
+    创建新的笔记；
+    删除当前笔记前显示确认对话框；
+    显示字体大小选择器；
+    切换笔记的检查列表模式；
+    分享笔记内容；
+    将笔记发送到桌面；
+    设置提醒；
+    删除提醒。*/
+
+
+/*setReminder()
+这个方法用于设置笔记的提醒时间。它创建了一个 DateTimePickerDialog 对话框，允许用户选择一个特定的时间作为提醒时间。用户选择后，会通过 OnDateTimeSetListener 回调设置笔记的提醒时间。*/
+    private void setReminder() {
+        DateTimePickerDialog d = new DateTimePickerDialog(this, System.currentTimeMillis());
+        d.setOnDateTimeSetListener(new OnDateTimeSetListener() {
+            public void OnDateTimeSet(AlertDialog dialog, long date) {
+                mWorkingNote.setAlertDate(date	, true);
+            }
+        });
+        d.show();
+    }
+
+    /**
+     * Share note to apps that support {@link Intent#ACTION_SEND} action
+     * and {@text/plain} type
+     */
+/*sendTo()
+此方法用于将笔记内容分享给支持 Intent.ACTION_SEND 动作的应用程序。它创建了一个 Intent，并将笔记文本作为 EXTRA_TEXT 添加进去，然后启动支持分享的应用程序列表供用户选择。*/
+    private void sendTo(Context context, String info) {
+        Intent intent = new Intent(Intent.ACTION_SEND);
+        intent.putExtra(Intent.EXTRA_TEXT, info);
+        intent.setType("text/plain");
+        context.startActivity(intent);
+    }
+
+/*createNewNote()
+此方法用于创建一个新的笔记。首先它会保存当前正在编辑的笔记（如果有），然后启动一个新的 NoteEditActivity 实例，并传入当前笔记所在的文件夹 ID。*/
+    private void createNewNote() {
+        // Firstly, save current editing notes
+        saveNote();
+
+        // For safety, start a new NoteEditActivity
+        finish();
+        Intent intent = new Intent(this, NoteEditActivity.class);
+        intent.setAction(Intent.ACTION_INSERT_OR_EDIT);
+        intent.putExtra(Notes.INTENT_EXTRA_FOLDER_ID, mWorkingNote.getFolderId());
+        startActivity(intent);
+    }
+
+/*deleteCurrentNote()
+此方法用于删除当前笔记。它首先检查笔记是否存在于数据库中，如果存在则删除笔记或将其移动到回收站（取决于应用是否处于同步模式）。之后标记笔记为已删除。*/
+    private void deleteCurrentNote() {
+        if (mWorkingNote.existInDatabase()) {
+            HashSet<Long> ids = new HashSet<Long>();
+            long id = mWorkingNote.getNoteId();
+            if (id != Notes.ID_ROOT_FOLDER) {
+                ids.add(id);
+            } else {
+                Log.d(TAG, "Wrong note id, should not happen");
+            }
+            if (!isSyncMode()) {
+                if (!DataUtils.batchDeleteNotes(getContentResolver(), ids)) {
+                    Log.e(TAG, "Delete Note error");
+                }
+            } else {
+                if (!DataUtils.batchMoveToFolder(getContentResolver(), ids, Notes.ID_TRASH_FOLER)) {
+                    Log.e(TAG, "Move notes to trash folder error, should not happens");
+                }
+            }
+        }
+        mWorkingNote.markDeleted(true);
+    }
+
+/*isSyncMode()
+这是一个辅助方法，用于检查应用程序是否处于同步模式。如果是同步模式，那么删除笔记时将会把笔记移到回收站文件夹而不是直接删除。*/
+    private boolean isSyncMode() {
+        return NotesPreferenceActivity.getSyncAccountName(this).trim().length() > 0;
+    }
+
+/*onClockAlertChanged()
+这个方法用于处理时钟提醒的设置变化。如果用户设置了提醒时间，则创建一个广播接收器的 Intent 和一个 Pending Intent，并使用 AlarmManager 在指定的时间触发提醒。如果取消了提醒，则取消先前设置的提醒。*/
+    public void onClockAlertChanged(long date, boolean set) {
+        /**
+         * User could set clock to an unsaved note, so before setting the
+         * alert clock, we should save the note first
+         */
+        if (!mWorkingNote.existInDatabase()) {
+            saveNote();
+        }
+        if (mWorkingNote.getNoteId() > 0) {
+            Intent intent = new Intent(this, AlarmReceiver.class);
+            intent.setData(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, mWorkingNote.getNoteId()));
+            PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
+            AlarmManager alarmManager = ((AlarmManager) getSystemService(ALARM_SERVICE));
+            showAlertHeader();
+            if(!set) {
+                alarmManager.cancel(pendingIntent);
+            } else {
+                alarmManager.set(AlarmManager.RTC_WAKEUP, date, pendingIntent);
+            }
+        } else {
+            /**
+             * There is the condition that user has input nothing (the note is
+             * not worthy saving), we have no note id, remind the user that he
+             * should input something
+             */
+            Log.e(TAG, "Clock alert setting error");
+            showToast(R.string.error_note_empty_for_clock);
+        }
+    }
+
+
+    public void onWidgetChanged() {
+        updateWidget();
+    }     /*当某个小部件发生改变时调用此方法，进而更新小部件。*/
+
+
+/*当从多行文本编辑模式中删除一行时：
+获取当前 mEditTextList 的子视图数量；
+如果只有一个子视图，则直接返回；
+否则循环遍历从 index+1 开始的所有子视图，并更新它们的索引；
+移除指定索引的子视图；
+更新前一个 NoteEditText 的索引；
+将删除行的内容附加到前一行的末尾；
+设置焦点并选择附加的文本。*/
+    public void onEditTextDelete(int index, String text) {   
+        int childCount = mEditTextList.getChildCount();
+        if (childCount == 1) {
+            return;
+        }
+
+        for (int i = index + 1; i < childCount; i++) {
+            ((NoteEditText) mEditTextList.getChildAt(i).findViewById(R.id.et_edit_text))
+                    .setIndex(i - 1);
+        }
+
+        mEditTextList.removeViewAt(index);
+        NoteEditText edit = null;
+        if(index == 0) {
+            edit = (NoteEditText) mEditTextList.getChildAt(0).findViewById(
+                    R.id.et_edit_text);
+        } else {
+            edit = (NoteEditText) mEditTextList.getChildAt(index - 1).findViewById(
+                    R.id.et_edit_text);
+        }
+        int length = edit.length();
+        edit.append(text);
+        edit.requestFocus();
+        edit.setSelection(length);
+    }
+
+
+
+/*当用户在多行文本编辑模式中输入回车时：
+检查索引是否超出 mEditTextList 的边界；
+创建一个新的列表项视图；
+将新视图添加到 mEditTextList 的指定索引位置；
+设置焦点并在文本开始处选择；
+更新所有后续 NoteEditText 的索引。*/
+    public void onEditTextEnter(int index, String text) {
+        /**
+         * Should not happen, check for debug
+         */
+        if(index > mEditTextList.getChildCount()) {
+            Log.e(TAG, "Index out of mEditTextList boundrary, should not happen");
+        }
+
+        View view = getListItem(text, index);
+        mEditTextList.addView(view, index);
+        NoteEditText edit = (NoteEditText) view.findViewById(R.id.et_edit_text);
+        edit.requestFocus();
+        edit.setSelection(0);
+        for (int i = index + 1; i < mEditTextList.getChildCount(); i++) {
+            ((NoteEditText) mEditTextList.getChildAt(i).findViewById(R.id.et_edit_text))
+                    .setIndex(i);
+        }
+    }
+
+
+/*当从普通文本编辑模式切换到检查列表模式时：
+清空 mEditTextList 中的所有视图；
+将文本分割成多个项；
+循环遍历每一项，并创建对应的列表项视图；
+添加最后一个空的列表项视图，并设置焦点；
+隐藏文本编辑器，并显示列表视图。*/
+    private void switchToListMode(String text) {
+        mEditTextList.removeAllViews();
+        String[] items = text.split("\n");
+        int index = 0;
+        for (String item : items) {
+            if(!TextUtils.isEmpty(item)) {
+                mEditTextList.addView(getListItem(item, index));
+                index++;
+            }
+        }
+        mEditTextList.addView(getListItem("", index));
+        mEditTextList.getChildAt(index).findViewById(R.id.et_edit_text).requestFocus();
+
+        mNoteEditor.setVisibility(View.GONE);
+        mEditTextList.setVisibility(View.VISIBLE);
+    }
+
+/*根据用户查询高亮文本中的匹配项：
+创建一个 SpannableString；
+如果查询字符串不为空，则编译一个正则表达式，并查找匹配项；
+使用背景颜色跨度标记匹配项；
+返回高亮后的文本。*/
+    private Spannable getHighlightQueryResult(String fullText, String userQuery) {
+        SpannableString spannable = new SpannableString(fullText == null ? "" : fullText);
+        if (!TextUtils.isEmpty(userQuery)) {
+            mPattern = Pattern.compile(userQuery);
+            Matcher m = mPattern.matcher(fullText);
+            int start = 0;
+            while (m.find(start)) {
+                spannable.setSpan(
+                        new BackgroundColorSpan(this.getResources().getColor(
+                                R.color.user_query_highlight)), m.start(), m.end(),
+                        Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
+                start = m.end();
+            }
+        }
+        return spannable;
+    }
+
+/*创建一个包含文本编辑控件和复选框的列表项视图：
+使用布局填充器创建视图；
+初始化 NoteEditText 并设置字体大小；
+设置复选框的监听器，以改变文本样式；
+根据文本内容初始化复选框状态；
+设置文本变化监听器；
+设置文本并高亮查询结果；
+返回创建的视图。*/
+    private View getListItem(String item, int index) {
+        View view = LayoutInflater.from(this).inflate(R.layout.note_edit_list_item, null);
+        final NoteEditText edit = (NoteEditText) view.findViewById(R.id.et_edit_text);
+        edit.setTextAppearance(this, TextAppearanceResources.getTexAppearanceResource(mFontSizeId));
+        CheckBox cb = ((CheckBox) view.findViewById(R.id.cb_edit_item));
+        cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {
+            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                if (isChecked) {
+                    edit.setPaintFlags(edit.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
+                } else {
+                    edit.setPaintFlags(Paint.ANTI_ALIAS_FLAG | Paint.DEV_KERN_TEXT_FLAG);
+                }
+            }
+        });
+
+        if (item.startsWith(TAG_CHECKED)) {
+            cb.setChecked(true);
+            edit.setPaintFlags(edit.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
+            item = item.substring(TAG_CHECKED.length(), item.length()).trim();
+        } else if (item.startsWith(TAG_UNCHECKED)) {
+            cb.setChecked(false);
+            edit.setPaintFlags(Paint.ANTI_ALIAS_FLAG | Paint.DEV_KERN_TEXT_FLAG);
+            item = item.substring(TAG_UNCHECKED.length(), item.length()).trim();
+        }
+
+        edit.setOnTextViewChangeListener(this);
+        edit.setIndex(index);
+        edit.setText(getHighlightQueryResult(item, mUserQuery));
+        return view;
+    }
+
+/*当 NoteEditText 中的文本发生变化时：
+检查索引是否超出范围；
+根据是否有文本决定是否显示复选框。*/
+    public void onTextChange(int index, boolean hasText) {
+        if (index >= mEditTextList.getChildCount()) {
+            Log.e(TAG, "Wrong index, should not happen");
+            return;
+        }
+        if(hasText) {
+            mEditTextList.getChildAt(index).findViewById(R.id.cb_edit_item).setVisibility(View.VISIBLE);
+        } else {
+            mEditTextList.getChildAt(index).findViewById(R.id.cb_edit_item).setVisibility(View.GONE);
+        }
+    }
+
+/*当笔记的模式从普通文本模式切换到检查列表模式或反之亦然时：
+如果新的模式是检查列表模式，则切换到检查列表模式；
+否则，获取当前编辑的文本，并更新文本编辑器的文本；
+调整视图的可见性。*/
+    public void onCheckListModeChanged(int oldMode, int newMode) {
+        if (newMode == TextNote.MODE_CHECK_LIST) {
+            switchToListMode(mNoteEditor.getText().toString());
+        } else {
+            if (!getWorkingText()) {
+                mWorkingNote.setWorkingText(mWorkingNote.getContent().replace(TAG_UNCHECKED + " ",
+                        ""));
+            }
+            mNoteEditor.setText(getHighlightQueryResult(mWorkingNote.getContent(), mUserQuery));
+            mEditTextList.setVisibility(View.GONE);
+            mNoteEditor.setVisibility(View.VISIBLE);
+        }
+    }
+
+/*获取当前正在编辑的文本内容：
+如果当前模式是检查列表模式，则构建字符串，并记录是否有选中项；
+否则，直接获取文本编辑器中的文本；
+返回是否有选中项的结果。*/
+    private boolean getWorkingText() {
+        boolean hasChecked = false;
+        if (mWorkingNote.getCheckListMode() == TextNote.MODE_CHECK_LIST) {
+            StringBuilder sb = new StringBuilder();
+            for (int i = 0; i < mEditTextList.getChildCount(); i++) {
+                View view = mEditTextList.getChildAt(i);
+                NoteEditText edit = (NoteEditText) view.findViewById(R.id.et_edit_text);
+                if (!TextUtils.isEmpty(edit.getText())) {
+                    if (((CheckBox) view.findViewById(R.id.cb_edit_item)).isChecked()) {
+                        sb.append(TAG_CHECKED).append(" ").append(edit.getText()).append("\n");
+                        hasChecked = true;
+                    } else {
+                        sb.append(TAG_UNCHECKED).append(" ").append(edit.getText()).append("\n");
+                    }
+                }
+            }
+            mWorkingNote.setWorkingText(sb.toString());
+        } else {
+            mWorkingNote.setWorkingText(mNoteEditor.getText().toString());
+        }
+        return hasChecked;
+    }
+
+/*保存当前笔记：
+获取当前编辑的文本；
+保存笔记；
+如果保存成功，设置结果码为成功；
+返回保存结果。*/
+    private boolean saveNote() {
+        getWorkingText();
+        boolean saved = mWorkingNote.saveNote();
+        if (saved) {
+            /**
+             * There are two modes from List view to edit view, open one note,
+             * create/edit a node. Opening node requires to the original
+             * position in the list when back from edit view, while creating a
+             * new node requires to the top of the list. This code
+             * {@link #RESULT_OK} is used to identify the create/edit state
+             */
+            setResult(RESULT_OK);
+        }
+        return saved;
+    }
+
+/*将笔记作为一个快捷方式发送到主屏幕：
+如果笔记不存在于数据库中，则先保存笔记；
+如果笔记有 ID，则创建快捷方式；
+否则，显示错误信息。*/
+    private void sendToDesktop() {
+        /**
+         * Before send message to home, we should make sure that current
+         * editing note is exists in databases. So, for new note, firstly
+         * save it
+         */
+        if (!mWorkingNote.existInDatabase()) {
+            saveNote();
+        }
+
+        if (mWorkingNote.getNoteId() > 0) {
+            Intent sender = new Intent();
+            Intent shortcutIntent = new Intent(this, NoteEditActivity.class);
+            shortcutIntent.setAction(Intent.ACTION_VIEW);
+            shortcutIntent.putExtra(Intent.EXTRA_UID, mWorkingNote.getNoteId());
+            sender.putExtra(Intent.EXTRA_SHORTCUT_INTENT, shortcutIntent);
+            sender.putExtra(Intent.EXTRA_SHORTCUT_NAME,
+                    makeShortcutIconTitle(mWorkingNote.getContent()));
+            sender.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE,
+                    Intent.ShortcutIconResource.fromContext(this, R.drawable.icon_app));
+            sender.putExtra("duplicate", true);
+            sender.setAction("com.android.launcher.action.INSTALL_SHORTCUT");
+            showToast(R.string.info_note_enter_desktop);
+            sendBroadcast(sender);
+        } else {
+            /**
+             * There is the condition that user has input nothing (the note is
+             * not worthy saving), we have no note id, remind the user that he
+             * should input something
+             */
+            Log.e(TAG, "Send to desktop error");
+            showToast(R.string.error_note_empty_for_send_to_desktop);
+        }
+    }
+
+/*截取笔记内容的一部分作为快捷方式的标题：
+去除检查列表标签；
+截取固定长度的文本作为标题；
+返回处理后的标题。*/
+    private String makeShortcutIconTitle(String content) {
+        content = content.replace(TAG_CHECKED, "");
+        content = content.replace(TAG_UNCHECKED, "");
+        return content.length() > SHORTCUT_ICON_TITLE_MAX_LEN ? content.substring(0,
+                SHORTCUT_ICON_TITLE_MAX_LEN) : content;
+    }
+
+/*显示一个 Toast 消息：
+
+可以直接传递资源 ID 和默认持续时间；
+或者传递资源 ID 和指定的持续时间。
+/
+    private void showToast(int resId) {
+        showToast(resId, Toast.LENGTH_SHORT);
+    }
+
+    private void showToast(int resId, int duration) {
+        Toast.makeText(this, resId, duration).show();
+    }
+}

NoteEditText.java

@@ -0,0 +1,217 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;/*定义包名 net.micode.notes.ui*/
+
+import android.content.Context;
+import android.graphics.Rect;
+import android.text.Layout;
+import android.text.Selection;
+import android.text.Spanned;
+import android.text.TextUtils;
+import android.text.style.URLSpan;
+import android.util.AttributeSet;
+import android.util.Log;
+import android.view.ContextMenu;
+import android.view.KeyEvent;
+import android.view.MenuItem;
+import android.view.MenuItem.OnMenuItemClickListener;
+import android.view.MotionEvent;
+import android.widget.EditText;/*导入所需的 Android 库文件*/
+
+import net.micode.notes.R;/*导入应用的资源文件*/
+
+import java.util.HashMap;/*导入 Java 的 HashMap 类*/
+import java.util.Map;
+
+public class NoteEditText extends EditText {  /*定义 NoteEditText 类，继承自 EditText*/
+    private static final String TAG = "NoteEditText";  /*定义一个用于日志输出的标签字符串*/
+    private int mIndex;
+    private int mSelectionStartBeforeDelete;  /*定义两个私有变量，mIndex 用于存储当前文本框的索引，mSelectionStartBeforeDelete 用于存储删除键按下之前的选择起始位置。*/
+
+    private static final String SCHEME_TEL = "tel:" ;
+    private static final String SCHEME_HTTP = "http:" ;
+    private static final String SCHEME_EMAIL = "mailto:" ;  /*定义几个常量字符串，表示不同的 URL 协议*/
+
+    private static final Map<String, Integer> sSchemaActionResMap = new HashMap<String, Integer>();
+    static {
+        sSchemaActionResMap.put(SCHEME_TEL, R.string.note_link_tel);
+        sSchemaActionResMap.put(SCHEME_HTTP, R.string.note_link_web);
+        sSchemaActionResMap.put(SCHEME_EMAIL, R.string.note_link_email);
+    }    /*定义一个静态的哈希映射表，用于存储不同 URL 协议到资源 ID 的映射。*/
+
+    /**
+     * Call by the {@link NoteEditActivity} to delete or add edit text
+     */
+    public interface OnTextViewChangeListener {
+        /**
+         * Delete current edit text when {@link KeyEvent#KEYCODE_DEL} happens
+         * and the text is null
+         */
+        void onEditTextDelete(int index, String text);
+
+        /**
+         * Add edit text after current edit text when {@link KeyEvent#KEYCODE_ENTER}
+         * happen
+         */
+        void onEditTextEnter(int index, String text);
+
+        /**
+         * Hide or show item option when text change
+         */
+        void onTextChange(int index, boolean hasText);
+    }   /*定义一个内部接口 OnTextViewChangeListener，包含三个方法，用于通知监听器文本框的删除、添加及文本变化。*/
+
+    private OnTextViewChangeListener mOnTextViewChangeListener;  /*定义一个私有变量，用于存储 OnTextViewChangeListener 的实例*/
+
+    public NoteEditText(Context context) {
+        super(context, null);
+        mIndex = 0;
+    }   /*构造函数，使用给定的上下文初始化 NoteEditText*/
+
+    public void setIndex(int index) {
+        mIndex = index;
+    }    /*设置当前文本框的索引*/
+
+    public void setOnTextViewChangeListener(OnTextViewChangeListener listener) {
+        mOnTextViewChangeListener = listener;
+    }   /*设置监听器实例*/
+
+    public NoteEditText(Context context, AttributeSet attrs) {
+        super(context, attrs, android.R.attr.editTextStyle);
+    }    /*构造函数，使用给定的上下文和属性集初始化 NoteEditText*/
+
+    public NoteEditText(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+        // TODO Auto-generated constructor stub
+    }    /*构造函数，使用给定的上下文、属性集和默认样式初始化 NoteEditText*/
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        switch (event.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+
+                int x = (int) event.getX();
+                int y = (int) event.getY();
+                x -= getTotalPaddingLeft();
+                y -= getTotalPaddingTop();
+                x += getScrollX();
+                y += getScrollY();
+
+                Layout layout = getLayout();
+                int line = layout.getLineForVertical(y);
+                int off = layout.getOffsetForHorizontal(line, x);
+                Selection.setSelection(getText(), off);
+                break;
+        }
+
+        return super.onTouchEvent(event);
+    }   /*重写 onTouchEvent 方法，处理触摸事件，特别是按下时设置文本选择的位置*/
+
+    @Override
+    public boolean onKeyDown(int keyCode, KeyEvent event) {
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_ENTER:
+                if (mOnTextViewChangeListener != null) {
+                    return false;
+                }
+                break;
+            case KeyEvent.KEYCODE_DEL:
+                mSelectionStartBeforeDelete = getSelectionStart();
+                break;
+            default:
+                break;
+        }
+        return super.onKeyDown(keyCode, event);
+    }   /*重写 onKeyDown 方法，处理按键按下事件，特别记录删除键按下时的选择起始位置。*/
+
+    @Override
+    public boolean onKeyUp(int keyCode, KeyEvent event) {
+        switch(keyCode) {
+            case KeyEvent.KEYCODE_DEL:
+                if (mOnTextViewChangeListener != null) {
+                    if (0 == mSelectionStartBeforeDelete && mIndex != 0) {
+                        mOnTextViewChangeListener.onEditTextDelete(mIndex, getText().toString());
+                        return true;
+                    }
+                } else {
+                    Log.d(TAG, "OnTextViewChangeListener was not seted");
+                }
+                break;
+            case KeyEvent.KEYCODE_ENTER:
+                if (mOnTextViewChangeListener != null) {
+                    int selectionStart = getSelectionStart();
+                    String text = getText().subSequence(selectionStart, length()).toString();
+                    setText(getText().subSequence(0, selectionStart));
+                    mOnTextViewChangeListener.onEditTextEnter(mIndex + 1, text);
+                } else {
+                    Log.d(TAG, "OnTextViewChangeListener was not seted");
+                }
+                break;
+            default:
+                break;
+        }
+        return super.onKeyUp(keyCode, event);
+    }    /*重写 onKeyUp 方法，处理按键释放事件，特别是处理删除键和回车键的操作*/
+
+    @Override
+    protected void onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect) {
+        if (mOnTextViewChangeListener != null) {
+            if (!focused && TextUtils.isEmpty(getText())) {
+                mOnTextViewChangeListener.onTextChange(mIndex, false);
+            } else {
+                mOnTextViewChangeListener.onTextChange(mIndex, true);
+            }
+        }
+        super.onFocusChanged(focused, direction, previouslyFocusedRect);
+    }    /*重写 onFocusChanged 方法，当焦点改变时通知监听器文本框的状态。*/
+
+    @Override
+    protected void onCreateContextMenu(ContextMenu menu) {
+        if (getText() instanceof Spanned) {
+            int selStart = getSelectionStart();
+            int selEnd = getSelectionEnd();
+
+            int min = Math.min(selStart, selEnd);
+            int max = Math.max(selStart, selEnd);
+
+            final URLSpan[] urls = ((Spanned) getText()).getSpans(min, max, URLSpan.class);
+            if (urls.length == 1) {
+                int defaultResId = 0;
+                for(String schema: sSchemaActionResMap.keySet()) {
+                    if(urls[0].getURL().indexOf(schema) >= 0) {
+                        defaultResId = sSchemaActionResMap.get(schema);
+                        break;
+                    }
+                }
+
+                if (defaultResId == 0) {
+                    defaultResId = R.string.note_link_other;
+                }
+
+                menu.add(0, 0, 0, defaultResId).setOnMenuItemClickListener(
+                        new OnMenuItemClickListener() {
+                            public boolean onMenuItemClick(MenuItem item) {
+                                // goto a new intent
+                                urls[0].onClick(NoteEditText.this);
+                                return true;
+                            }
+                        });
+            }
+        }
+        super.onCreateContextMenu(menu);
+    }   /*重写 onCreateContextMenu 方法，当创建上下文菜单时，根据选定的链接类型添加相应的菜单项。*/
+}

NoteItemData.java

@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;/*声明类所在的包*/
+
+import android.content.Context;
+import android.database.Cursor;
+import android.text.TextUtils;  /*导入必要的 Android 库*/
+
+import net.micode.notes.data.Contact;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.tool.DataUtils;   /*导入笔记应用相关的数据模型和工具类*/
+
+
+public class NoteItemData {
+    static final String [] PROJECTION = new String [] {
+        NoteColumns.ID,
+        NoteColumns.ALERTED_DATE,
+        NoteColumns.BG_COLOR_ID,
+        NoteColumns.CREATED_DATE,
+        NoteColumns.HAS_ATTACHMENT,
+        NoteColumns.MODIFIED_DATE,
+        NoteColumns.NOTES_COUNT,
+        NoteColumns.PARENT_ID,
+        NoteColumns.SNIPPET,
+        NoteColumns.TYPE,
+        NoteColumns.WIDGET_ID,
+        NoteColumns.WIDGET_TYPE,
+    };             /*定义一个静态数组 PROJECTION，包含了从数据库查询笔记时需要的所有列名*/
+
+    private static final int ID_COLUMN                    = 0;
+    private static final int ALERTED_DATE_COLUMN          = 1;
+    private static final int BG_COLOR_ID_COLUMN           = 2;
+    private static final int CREATED_DATE_COLUMN          = 3;
+    private static final int HAS_ATTACHMENT_COLUMN        = 4;
+    private static final int MODIFIED_DATE_COLUMN         = 5;
+    private static final int NOTES_COUNT_COLUMN           = 6;
+    private static final int PARENT_ID_COLUMN             = 7;
+    private static final int SNIPPET_COLUMN               = 8;
+    private static final int TYPE_COLUMN                  = 9;
+    private static final int WIDGET_ID_COLUMN             = 10;
+    private static final int WIDGET_TYPE_COLUMN           = 11;  /*定义了查询结果中各列对应的索引值*/
+
+    private long mId;
+    private long mAlertDate;
+    private int mBgColorId;
+    private long mCreatedDate;
+    private boolean mHasAttachment;
+    private long mModifiedDate;
+    private int mNotesCount;
+    private long mParentId;
+    private String mSnippet;
+    private int mType;
+    private int mWidgetId;
+    private int mWidgetType;
+    private String mName;
+    private String mPhoneNumber;  /*声明了类的成员变量，用于存储笔记的数据*/
+
+    private boolean mIsLastItem;
+    private boolean mIsFirstItem;
+    private boolean mIsOnlyOneItem;
+    private boolean mIsOneNoteFollowingFolder;
+    private boolean mIsMultiNotesFollowingFolder;  /*声明了几个布尔类型的成员变量，用于标记笔记在列表中的位置关系*/
+
+    public NoteItemData(Context context, Cursor cursor) {
+        mId = cursor.getLong(ID_COLUMN);
+        mAlertDate = cursor.getLong(ALERTED_DATE_COLUMN);
+        mBgColorId = cursor.getInt(BG_COLOR_ID_COLUMN);
+        mCreatedDate = cursor.getLong(CREATED_DATE_COLUMN);
+        mHasAttachment = (cursor.getInt(HAS_ATTACHMENT_COLUMN) > 0) ? true : false;
+        mModifiedDate = cursor.getLong(MODIFIED_DATE_COLUMN);
+        mNotesCount = cursor.getInt(NOTES_COUNT_COLUMN);
+        mParentId = cursor.getLong(PARENT_ID_COLUMN);
+        mSnippet = cursor.getString(SNIPPET_COLUMN);
+        mSnippet = mSnippet.replace(NoteEditActivity.TAG_CHECKED, "").replace(
+                NoteEditActivity.TAG_UNCHECKED, "");
+        mType = cursor.getInt(TYPE_COLUMN);
+        mWidgetId = cursor.getInt(WIDGET_ID_COLUMN);
+        mWidgetType = cursor.getInt(WIDGET_TYPE_COLUMN);
+
+        mPhoneNumber = "";
+        if (mParentId == Notes.ID_CALL_RECORD_FOLDER) {
+            mPhoneNumber = DataUtils.getCallNumberByNoteId(context.getContentResolver(), mId);
+            if (!TextUtils.isEmpty(mPhoneNumber)) {
+                mName = Contact.getContact(context, mPhoneNumber);
+                if (mName == null) {
+                    mName = mPhoneNumber;
+                }
+            }
+        }
+
+        if (mName == null) {
+            mName = "";
+        }
+        checkPostion(cursor);
+    }                /*构造函数接收一个 Context 和一个 Cursor，从 Cursor 中读取笔记的数据，并初始化成员变量*/
+
+    private void checkPostion(Cursor cursor) {
+        mIsLastItem = cursor.isLast() ? true : false;
+        mIsFirstItem = cursor.isFirst() ? true : false;
+        mIsOnlyOneItem = (cursor.getCount() == 1);
+        mIsMultiNotesFollowingFolder = false;
+        mIsOneNoteFollowingFolder = false;
+
+        if (mType == Notes.TYPE_NOTE && !mIsFirstItem) {
+            int position = cursor.getPosition();
+            if (cursor.moveToPrevious()) {
+                if (cursor.getInt(TYPE_COLUMN) == Notes.TYPE_FOLDER
+                        || cursor.getInt(TYPE_COLUMN) == Notes.TYPE_SYSTEM) {
+                    if (cursor.getCount() > (position + 1)) {
+                        mIsMultiNotesFollowingFolder = true;
+                    } else {
+                        mIsOneNoteFollowingFolder = true;
+                    }
+                }
+                if (!cursor.moveToNext()) {
+                    throw new IllegalStateException("cursor move to previous but can't move back");
+                }
+            }
+        }
+    }           /*检查笔记在列表中的位置，并更新相应的位置标志*/
+
+    public boolean isOneFollowingFolder() {
+        return mIsOneNoteFollowingFolder;
+    }      /*返回笔记是否是紧随其后的单个笔记*/
+
+    public boolean isMultiFollowingFolder() {
+        return mIsMultiNotesFollowingFolder;
+    }     /*返回笔记是否是紧随其后的多个笔记之一*/
+
+    public boolean isLast() {
+        return mIsLastItem;
+    }     /*返回笔记是否是列表中的最后一个*/
+
+    public String getCallName() {
+        return mName;
+    }    /*返回与笔记关联的联系人姓名*/
+
+    public boolean isFirst() {
+        return mIsFirstItem;
+    }    /*返回笔记是否是列表中的第一个*/
+
+    public boolean isSingle() {
+        return mIsOnlyOneItem;
+    }    /*返回列表中是否只有一个笔记*/
+
+    public long getId() {
+        return mId;
+    }   /*返回笔记的 ID*/
+
+    public long getAlertDate() {
+        return mAlertDate;
+    }    /*返回笔记的提醒日期*/
+
+    public long getCreatedDate() {
+        return mCreatedDate;
+    }   /*返回笔记的创建日期*/
+
+    public boolean hasAttachment() {
+        return mHasAttachment;
+    }    /*返回笔记是否有附件*/
+
+    public long getModifiedDate() {
+        return mModifiedDate;
+    }   /*返回笔记的最后修改日期*/
+
+    public int getBgColorId() {
+        return mBgColorId;
+    }    /*返回笔记背景颜色的 ID*/
+
+    public long getParentId() {
+        return mParentId;
+    }   /*返回笔记所属文件夹的 ID*/
+
+    public int getNotesCount() {
+        return mNotesCount;
+    }   /*返回笔记的数量*/
+
+    public long getFolderId () {
+        return mParentId;
+    }   /*返回笔记所属文件夹的 ID*/
+
+    public int getType() {
+        return mType;
+    }   /*返回笔记的类型*/
+
+    public int getWidgetType() {
+        return mWidgetType;
+    }   /*返回小部件的类型*/
+
+    public int getWidgetId() {
+        return mWidgetId;
+    }   /*返回小部件的 ID*/
+
+    public String getSnippet() {
+        return mSnippet;
+    }   /*返回笔记的摘要*/
+
+    public boolean hasAlert() {
+        return (mAlertDate > 0);
+    }    /*返回笔记是否有提醒设置*/
+
+    public boolean isCallRecord() {
+        return (mParentId == Notes.ID_CALL_RECORD_FOLDER && !TextUtils.isEmpty(mPhoneNumber));
+    }   /*返回笔记是否属于通话记录类型*/
+
+    public static int getNoteType(Cursor cursor) {
+        return cursor.getInt(TYPE_COLUMN);
+    }   /*静态方法，从游标中获取笔记的类型*/
+}

NoteWidgetProvider.java

@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.widget;
+import android.app.PendingIntent;
+import android.appwidget.AppWidgetManager;
+import android.appwidget.AppWidgetProvider;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.Intent;
+import android.database.Cursor;
+import android.util.Log;
+import android.widget.RemoteViews;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.tool.ResourceParser;
+import net.micode.notes.ui.NoteEditActivity;
+import net.micode.notes.ui.NotesListActivity;
+
+public abstract class NoteWidgetProvider extends AppWidgetProvider {  /*定义查询数据库时需要获取的列名数组*/
+    public static final String [] PROJECTION = new String [] {
+        NoteColumns.ID,  /*笔记ID*/
+        NoteColumns.BG_COLOR_ID,  /*背景颜色ID*/
+        NoteColumns.SNIPPET   /*笔记片段*/
+    };
+/*列索引常量，方便后续使用*/
+    public static final int COLUMN_ID           = 0;
+    public static final int COLUMN_BG_COLOR_ID  = 1;
+    public static final int COLUMN_SNIPPET      = 2;
+/*日志标签*/
+    private static final String TAG = "NoteWidgetProvider";
+
+    @Override
+    public void onDeleted(Context context, int[] appWidgetIds) {   /*当小部件被删除时，更新数据库中的 WIDGET_ID 为无效值*/
+        ContentValues values = new ContentValues();
+        values.put(NoteColumns.WIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID);
+        for (int i = 0; i < appWidgetIds.length; i++) {
+            context.getContentResolver().update(Notes.CONTENT_NOTE_URI,
+                    values,
+                    NoteColumns.WIDGET_ID + "=?",
+                    new String[] { String.valueOf(appWidgetIds[i])});
+        }
+    }
+/*根据小部件ID查询笔记信息*/
+    private Cursor getNoteWidgetInfo(Context context, int widgetId) {
+        return context.getContentResolver().query(Notes.CONTENT_NOTE_URI,
+                PROJECTION,
+                NoteColumns.WIDGET_ID + "=? AND " + NoteColumns.PARENT_ID + "<>?",
+                new String[] { String.valueOf(widgetId), String.valueOf(Notes.ID_TRASH_FOLER) },
+                null);
+    }
+/*更新小部件的显示内容*/
+    protected void update(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
+        update(context, appWidgetManager, appWidgetIds, false);
+    }
+/*更新小部件的显示内容，支持隐私模式*/
+    private void update(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds,
+            boolean privacyMode) {
+        for (int i = 0; i < appWidgetIds.length; i++) {
+            if (appWidgetIds[i] != AppWidgetManager.INVALID_APPWIDGET_ID) {
+                /*初始化背景颜色ID和笔记片段*/
+                int bgId = ResourceParser.getDefaultBgId(context);
+                String snippet = "";
+                /*创建一个 Intent 用于启动 NoteEditActivity*/
+                Intent intent = new Intent(context, NoteEditActivity.class);
+                intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
+                intent.putExtra(Notes.INTENT_EXTRA_WIDGET_ID, appWidgetIds[i]);
+                intent.putExtra(Notes.INTENT_EXTRA_WIDGET_TYPE, getWidgetType());
+                /*查询数据库获取笔记信息*/
+                Cursor c = getNoteWidgetInfo(context, appWidgetIds[i]);
+                if (c != null && c.moveToFirst()) {
+                    if (c.getCount() > 1) {
+                        /*如果有多个笔记与同一个小部件ID关联，记录错误并返回*/
+                        Log.e(TAG, "Multiple message with same widget id:" + appWidgetIds[i]);
+                        c.close();
+                        return;
+                    }
+                    snippet = c.getString(COLUMN_SNIPPET);
+                    bgId = c.getInt(COLUMN_BG_COLOR_ID);
+                    intent.putExtra(Intent.EXTRA_UID, c.getLong(COLUMN_ID));
+                    intent.setAction(Intent.ACTION_VIEW);
+                } else {
+                    /*如果没有找到笔记，显示默认的“没有内容”消息*/
+                    snippet = context.getResources().getString(R.string.widget_havenot_content);
+                    intent.setAction(Intent.ACTION_INSERT_OR_EDIT);
+                }
+
+                if (c != null) {
+                    c.close();
+                }
+                /*创建 RemoteViews 对象，用于更新小部件的 UI*/
+                RemoteViews rv = new RemoteViews(context.getPackageName(), getLayoutId());
+                rv.setImageViewResource(R.id.widget_bg_image, getBgResourceId(bgId));
+                intent.putExtra(Notes.INTENT_EXTRA_BACKGROUND_ID, bgId);
+                /**
+                 * Generate the pending intent to start host for the widget
+                 */
+                /*创建 PendingIntent 用于启动 Activity*/
+                PendingIntent pendingIntent = null;
+                if (privacyMode) {
+                    /*如果启用隐私模式，显示特定的隐私模式文本*/
+                    rv.setTextViewText(R.id.widget_text,
+                            context.getString(R.string.widget_under_visit_mode));
+                    pendingIntent = PendingIntent.getActivity(context, appWidgetIds[i], new Intent(
+                            context, NotesListActivity.class), PendingIntent.FLAG_UPDATE_CURRENT);
+                } else {
+                    /*正常模式下，显示笔记片段*/
+                    rv.setTextViewText(R.id.widget_text, snippet);
+                    pendingIntent = PendingIntent.getActivity(context, appWidgetIds[i], intent,
+                            PendingIntent.FLAG_UPDATE_CURRENT);
+                }
+                /*设置点击小部件时触发的 PendingIntent*/
+                rv.setOnClickPendingIntent(R.id.widget_text, pendingIntent);
+                /*更新小部件*/
+                appWidgetManager.updateAppWidget(appWidgetIds[i], rv);
+            }
+        }
+    }
+    /*抽象方法：获取背景资源ID*/
+    protected abstract int getBgResourceId(int bgId);
+    /*抽象方法：获取布局资源ID*/
+    protected abstract int getLayoutId();
+    /*抽象方法：获取小部件类型*/
+    protected abstract int getWidgetType();
+}

NoteWidgetProvider_2x.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.widget;
+
+import android.appwidget.AppWidgetManager;
+import android.content.Context;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.tool.ResourceParser;
+
+
+public class NoteWidgetProvider_2x extends NoteWidgetProvider {
+    @Override
+    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
+        /*调用父类的 update 方法来更新小部件*/
+        super.update(context, appWidgetManager, appWidgetIds);
+    }
+
+    @Override
+    protected int getLayoutId() {
+        /*返回 2x 大小的小部件的布局资源ID*/
+        return R.layout.widget_2x;
+    }
+
+    @Override
+    protected int getBgResourceId(int bgId) {
+        /*根据背景颜色ID获取 2x 大小的小部件的背景资源ID*/
+        return ResourceParser.WidgetBgResources.getWidget2xBgResource(bgId);
+    }
+
+    @Override
+    protected int getWidgetType() {
+        /*返回 2x 大小的小部件类型*/
+        return Notes.TYPE_WIDGET_2X;
+    }
+}

NoteWidgetProvider_4x.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.widget;
+
+import android.appwidget.AppWidgetManager;
+import android.content.Context;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.tool.ResourceParser;
+
+
+public class NoteWidgetProvider_4x extends NoteWidgetProvider {  /*NoteWidgetProvider_4x 继承自 NoteWidgetProvider，实现了其抽象方法*/
+    @Override
+    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
+        /*调用父类的 update 方法来更新小部件*/
+        super.update(context, appWidgetManager, appWidgetIds);
+    }
+
+    protected int getLayoutId() {
+        /*返回 4x 大小的小部件的布局资源ID*/
+        return R.layout.widget_4x;
+    }
+
+    @Override
+    protected int getBgResourceId(int bgId) {
+        /*根据背景颜色ID获取 4x 大小的小部件的背景资源ID*/
+        return ResourceParser.WidgetBgResources.getWidget4xBgResource(bgId);
+    }
+
+    @Override
+    protected int getWidgetType() {
+        /*返回 4x 大小的小部件类型*/
+        return Notes.TYPE_WIDGET_4X;
+    }
+}

NotesListActivity.java

@@ -0,0 +1,954 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui; /*声明类所在的包名*/
+
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.app.Dialog;
+import android.appwidget.AppWidgetManager;
+import android.content.AsyncQueryHandler;
+import android.content.ContentResolver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.database.Cursor;
+import android.os.AsyncTask;
+import android.os.Bundle;
+import android.preference.PreferenceManager;
+import android.text.Editable;
+import android.text.TextUtils;
+import android.text.TextWatcher;
+import android.util.Log;
+import android.view.ActionMode;
+import android.view.ContextMenu;
+import android.view.ContextMenu.ContextMenuInfo;
+import android.view.Display;
+import android.view.HapticFeedbackConstants;
+import android.view.LayoutInflater;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.MenuItem.OnMenuItemClickListener;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.View.OnClickListener;
+import android.view.View.OnCreateContextMenuListener;
+import android.view.View.OnTouchListener;
+import android.view.inputmethod.InputMethodManager;
+import android.widget.AdapterView;
+import android.widget.AdapterView.OnItemClickListener;
+import android.widget.AdapterView.OnItemLongClickListener;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.ListView;
+import android.widget.PopupMenu;
+import android.widget.TextView;
+import android.widget.Toast;  /*导入所需的 Android 库文件*/
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.gtask.remote.GTaskSyncService;
+import net.micode.notes.model.WorkingNote;
+import net.micode.notes.tool.BackupUtils;
+import net.micode.notes.tool.DataUtils;
+import net.micode.notes.tool.ResourceParser;
+import net.micode.notes.ui.NotesListAdapter.AppWidgetAttribute;
+import net.micode.notes.widget.NoteWidgetProvider_2x;
+import net.micode.notes.widget.NoteWidgetProvider_4x;  /*导入应用程序特有的类和资源*/
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.HashSet;
+
+public class NotesListActivity extends Activity implements OnClickListener, OnItemLongClickListener {  /*定义一个名为 NotesListActivity 的公共类，继承自 Activity 并实现了 OnClickListener 和 OnItemLongClickListener 接口*/
+    private static final int FOLDER_NOTE_LIST_QUERY_TOKEN = 0;
+
+    private static final int FOLDER_LIST_QUERY_TOKEN      = 1;   /*定义了一些常量，用于标识查询操作的令牌*/
+
+    private static final int MENU_FOLDER_DELETE = 0;
+
+    private static final int MENU_FOLDER_VIEW = 1;
+
+    private static final int MENU_FOLDER_CHANGE_NAME = 2;   /*定义了菜单项的常量标识符*/
+
+    private static final String PREFERENCE_ADD_INTRODUCTION = "net.micode.notes.introduction";   /*定义了一个偏好设置的键名，用于标记是否已向用户添加过介绍*/
+
+    private enum ListEditState {
+        NOTE_LIST, SUB_FOLDER, CALL_RECORD_FOLDER
+    };        /*定义了一个枚举类型 ListEditState，用于标识当前编辑状态*/
+
+    private ListEditState mState;
+
+    private BackgroundQueryHandler mBackgroundQueryHandler;
+
+    private NotesListAdapter mNotesListAdapter;
+
+    private ListView mNotesListView;
+
+    private Button mAddNewNote;
+
+    private boolean mDispatch;
+
+    private int mOriginY;
+
+    private int mDispatchY;
+
+    private TextView mTitleBar;
+
+    private long mCurrentFolderId;
+
+    private ContentResolver mContentResolver;
+
+    private ModeCallback mModeCallBack; /*声明了一些私有成员变量，用于存储活动的状态和其他相关信息*/
+
+    private static final String TAG = "NotesListActivity"; /*定义了一个日志标签字符串*/
+
+    public static final int NOTES_LISTVIEW_SCROLL_RATE = 30;  /*定义了一个整型常量，用于控制列表视图的滚动速率*/
+
+    private NoteItemData mFocusNoteDataItem;   /*声明了一个 NoteItemData 类型的变量，用于存储当前聚焦的笔记数据*/
+
+    private static final String NORMAL_SELECTION = NoteColumns.PARENT_ID + "=?";
+
+    private static final String ROOT_FOLDER_SELECTION = "(" + NoteColumns.TYPE + "<>"
+            + Notes.TYPE_SYSTEM + " AND " + NoteColumns.PARENT_ID + "=?)" + " OR ("
+            + NoteColumns.ID + "=" + Notes.ID_CALL_RECORD_FOLDER + " AND "
+            + NoteColumns.NOTES_COUNT + ">0)";     /*定义了用于数据库查询的 SQL 选择条件字符串*/
+
+    private final static int REQUEST_CODE_OPEN_NODE = 102;
+    private final static int REQUEST_CODE_NEW_NODE  = 103;   /*定义了请求码常量，用于标识不同的请求来源*/
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.note_list);
+        initResources();
+
+        /**
+         * Insert an introduction when user firstly use this application
+         */
+        setAppInfoFromRawRes();
+    }     /*覆盖 onCreate 方法，设置布局并初始化资源*/
+
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+        if (resultCode == RESULT_OK
+                && (requestCode == REQUEST_CODE_OPEN_NODE || requestCode == REQUEST_CODE_NEW_NODE)) {
+            mNotesListAdapter.changeCursor(null);
+        } else {
+            super.onActivityResult(requestCode, resultCode, data);
+        }
+    }    /*覆盖 onActivityResult 方法，处理子活动返回的结果*/
+
+    private void setAppInfoFromRawRes() {
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
+        if (!sp.getBoolean(PREFERENCE_ADD_INTRODUCTION, false)) {
+            StringBuilder sb = new StringBuilder();
+            InputStream in = null;
+            try {
+                 in = getResources().openRawResource(R.raw.introduction);
+                if (in != null) {
+                    InputStreamReader isr = new InputStreamReader(in);
+                    BufferedReader br = new BufferedReader(isr);
+                    char [] buf = new char[1024];
+                    int len = 0;
+                    while ((len = br.read(buf)) > 0) {
+                        sb.append(buf, 0, len);
+                    }
+                } else {
+                    Log.e(TAG, "Read introduction file error");
+                    return;
+                }
+            } catch (IOException e) {
+                e.printStackTrace();
+                return;
+            } finally {
+                if(in != null) {
+                    try {
+                        in.close();
+                    } catch (IOException e) {
+                        // TODO Auto-generated catch block
+                        e.printStackTrace();
+                    }
+                }
+            }
+
+            WorkingNote note = WorkingNote.createEmptyNote(this, Notes.ID_ROOT_FOLDER,
+                    AppWidgetManager.INVALID_APPWIDGET_ID, Notes.TYPE_WIDGET_INVALIDE,
+                    ResourceParser.RED);
+            note.setWorkingText(sb.toString());
+            if (note.saveNote()) {
+                sp.edit().putBoolean(PREFERENCE_ADD_INTRODUCTION, true).commit();
+            } else {
+                Log.e(TAG, "Save introduction note error");
+                return;
+            }
+        }
+    }     /*定义了一个私有方法 setAppInfoFromRawRes，用于从资源文件中读取介绍信息，并保存为一条新的笔记，同时更新偏好设置，标记已添加介绍信息*/
+
+    @Override
+    protected void onStart() {
+        super.onStart();
+        startAsyncNotesListQuery();
+    }      /*覆盖了 onStart 方法，在活动变为活跃状态时调用；先调用父类的 onStart 方法；然后开始异步查询笔记列表*/
+
+    private void initResources() {
+        mContentResolver = this.getContentResolver();
+        mBackgroundQueryHandler = new BackgroundQueryHandler(this.getContentResolver());
+        mCurrentFolderId = Notes.ID_ROOT_FOLDER;
+        mNotesListView = (ListView) findViewById(R.id.notes_list);
+        mNotesListView.addFooterView(LayoutInflater.from(this).inflate(R.layout.note_list_footer, null),
+                null, false);
+        mNotesListView.setOnItemClickListener(new OnListItemClickListener());
+        mNotesListView.setOnItemLongClickListener(this);
+        mNotesListAdapter = new NotesListAdapter(this);
+        mNotesListView.setAdapter(mNotesListAdapter);
+        mAddNewNote = (Button) findViewById(R.id.btn_new_note);
+        mAddNewNote.setOnClickListener(this);
+        mAddNewNote.setOnTouchListener(new NewNoteOnTouchListener());
+        mDispatch = false;
+        mDispatchY = 0;
+        mOriginY = 0;
+        mTitleBar = (TextView) findViewById(R.id.tv_title_bar);
+        mState = ListEditState.NOTE_LIST;
+        mModeCallBack = new ModeCallback();
+    }           /*定义了一个私有方法 initResources 用于初始化活动中的资源；获取 ContentResolver 对象；创建一个背景查询处理器；设置当前文件夹为根文件夹；获取 ListView 并设置其脚注视图；设置 ListView 的点击监听器和长按监听器；创建 NotesListAdapter 并将其设置为 ListView 的适配器；获取“新建笔记”按钮，并设置其点击监听器和触摸监听器；初始化一些布尔值和整数值；获取标题栏并设置当前状态为笔记列表；创建模式回调对象*/
+
+    private class ModeCallback implements ListView.MultiChoiceModeListener, OnMenuItemClickListener {
+        private DropdownMenu mDropDownMenu;
+        private ActionMode mActionMode;
+        private MenuItem mMoveMenu;
+
+        public boolean onCreateActionMode(ActionMode mode, Menu menu) {
+            getMenuInflater().inflate(R.menu.note_list_options, menu);
+            menu.findItem(R.id.delete).setOnMenuItemClickListener(this);
+            mMoveMenu = menu.findItem(R.id.move);
+            if (mFocusNoteDataItem.getParentId() == Notes.ID_CALL_RECORD_FOLDER
+                    || DataUtils.getUserFolderCount(mContentResolver) == 0) {
+                mMoveMenu.setVisible(false);
+            } else {
+                mMoveMenu.setVisible(true);
+                mMoveMenu.setOnMenuItemClickListener(this);
+            }
+            mActionMode = mode;
+            mNotesListAdapter.setChoiceMode(true);
+            mNotesListView.setLongClickable(false);
+            mAddNewNote.setVisibility(View.GONE);
+
+            View customView = LayoutInflater.from(NotesListActivity.this).inflate(
+                    R.layout.note_list_dropdown_menu, null);
+            mode.setCustomView(customView);
+            mDropDownMenu = new DropdownMenu(NotesListActivity.this,
+                    (Button) customView.findViewById(R.id.selection_menu),
+                    R.menu.note_list_dropdown);
+            mDropDownMenu.setOnDropdownMenuItemClickListener(new PopupMenu.OnMenuItemClickListener(){
+                public boolean onMenuItemClick(MenuItem item) {
+                    mNotesListAdapter.selectAll(!mNotesListAdapter.isAllSelected());
+                    updateMenu();
+                    return true;
+                }
+
+            });
+            return true;
+        }        /*定义了一个内部类 ModeCallback 实现了 ListView.MultiChoiceModeListener 和 OnMenuItemClickListener 接口；声明了一些成员变量；实现了 onCreateActionMode 方法，加载选项菜单，并设置删除菜单项的点击监听器；如果当前项目在通话记录文件夹或用户没有其他文件夹，则隐藏移动菜单项；否则，设置移动菜单项的监听器；设置当前多选模式；启用适配器的多选模式，禁用 ListView 的长按可点击性，隐藏“新建笔记”按钮；创建自定义视图并设置为当前模式的自定义视图；创建下拉菜单并设置其监听器；实现了一个匿名内部类来处理下拉菜单项的点击事件，切换全选状态，并更新菜单；最后返回 true 表示菜单已创建*/
+
+        private void updateMenu() {
+            int selectedCount = mNotesListAdapter.getSelectedCount();
+            // Update dropdown menu
+            String format = getResources().getString(R.string.menu_select_title, selectedCount);
+            mDropDownMenu.setTitle(format);
+            MenuItem item = mDropDownMenu.findItem(R.id.action_select_all);
+            if (item != null) {
+                if (mNotesListAdapter.isAllSelected()) {
+                    item.setChecked(true);
+                    item.setTitle(R.string.menu_deselect_all);
+                } else {
+                    item.setChecked(false);
+                    item.setTitle(R.string.menu_select_all);
+                }
+            }
+        }      /*定义了一个私有方法 updateMenu 用于更新菜单的显示状态；获取当前选择的数量；设置下拉菜单的标题；查找全选菜单项并根据当前全选状态设置其标题和选中状态*/
+
+        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
+            // TODO Auto-generated method stub
+            return false;
+        }
+
+        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
+            // TODO Auto-generated method stub
+            return false;
+        }
+
+        public void onDestroyActionMode(ActionMode mode) {
+            mNotesListAdapter.setChoiceMode(false);
+            mNotesListView.setLongClickable(true);
+            mAddNewNote.setVisibility(View.VISIBLE);
+        }
+
+        public void finishActionMode() {
+            mActionMode.finish();
+        }
+
+        public void onItemCheckedStateChanged(ActionMode mode, int position, long id,
+                boolean checked) {
+            mNotesListAdapter.setCheckedItem(position, checked);
+            updateMenu();
+        }
+
+        public boolean onMenuItemClick(MenuItem item) {
+            if (mNotesListAdapter.getSelectedCount() == 0) {
+                Toast.makeText(NotesListActivity.this, getString(R.string.menu_select_none),
+                        Toast.LENGTH_SHORT).show();
+                return true;
+            }
+
+            switch (item.getItemId()) {
+                case R.id.delete:
+                    AlertDialog.Builder builder = new AlertDialog.Builder(NotesListActivity.this);
+                    builder.setTitle(getString(R.string.alert_title_delete));
+                    builder.setIcon(android.R.drawable.ic_dialog_alert);
+                    builder.setMessage(getString(R.string.alert_message_delete_notes,
+                                             mNotesListAdapter.getSelectedCount()));
+                    builder.setPositiveButton(android.R.string.ok,
+                                             new DialogInterface.OnClickListener() {
+                                                 public void onClick(DialogInterface dialog,
+                                                         int which) {
+                                                     batchDelete();
+                                                 }
+                                             });
+                    builder.setNegativeButton(android.R.string.cancel, null);
+                    builder.show();
+                    break;
+                case R.id.move:
+                    startQueryDestinationFolders();
+                    break;
+                default:
+                    return false;
+            }
+            return true;
+        }
+    }          /*实现了 onPrepareActionMode 方法，该方法在每次进入多选模式之前被调用，这里返回 false 表示不做额外处理；实现了 onActionItemClicked 方法，当在多选模式下单击菜单项时调用，这里返回 false 表示不做额外处理；实现了 onDestroyActionMode 方法，在退出多选模式时调用，恢复适配器和 ListView 的默认行为，并显示“新建笔记”按钮；定义了一个 finishActionMode 方法来结束多选模式；实现了 onItemCheckedStateChanged 方法，在项目选择状态改变时调用，更新适配器的选中状态并更新菜单；实现了 onMenuItemClick 方法，在菜单项被点击时调用，如果没有任何项目被选中则显示提示信息；如果点击的是删除菜单项，则创建一个确认删除对话框；如果点击的是移动菜单项，则开始查询目标文件夹*/
+
+    private class NewNoteOnTouchListener implements OnTouchListener {
+
+        public boolean onTouch(View v, MotionEvent event) {
+            switch (event.getAction()) {
+                case MotionEvent.ACTION_DOWN: {
+                    Display display = getWindowManager().getDefaultDisplay();
+                    int screenHeight = display.getHeight();
+                    int newNoteViewHeight = mAddNewNote.getHeight();
+                    int start = screenHeight - newNoteViewHeight;
+                    int eventY = start + (int) event.getY();
+                    /**
+                     * Minus TitleBar's height
+                     */
+                    if (mState == ListEditState.SUB_FOLDER) {
+                        eventY -= mTitleBar.getHeight();
+                        start -= mTitleBar.getHeight();
+                    }        /*定义了一个内部类 NewNoteOnTouchListener 实现了 OnTouchListener 接口；实现了 onTouch 方法来处理触摸事件；根据触摸事件的动作进行不同的处理；当检测到触摸按下时，计算屏幕高度和按钮高度，调整触摸事件的 Y 坐标；如果当前状态是在子文件夹内，则减去标题栏的高度*/
+                    /**
+                     * HACKME:When click the transparent part of "New Note" button, dispatch
+                     * the event to the list view behind this button. The transparent part of
+                     * "New Note" button could be expressed by formula y=-0.12x+94（Unit:pixel）
+                     * and the line top of the button. The coordinate based on left of the "New
+                     * Note" button. The 94 represents maximum height of the transparent part.
+                     * Notice that, if the background of the button changes, the formula should
+                     * also change. This is very bad, just for the UI designer's strong requirement.
+                     */
+                    if (event.getY() < (event.getX() * (-0.12) + 94)) {
+                        View view = mNotesListView.getChildAt(mNotesListView.getChildCount() - 1
+                                - mNotesListView.getFooterViewsCount());
+                        if (view != null && view.getBottom() > start
+                                && (view.getTop() < (start + 94))) {
+                            mOriginY = (int) event.getY();
+                            mDispatchY = eventY;
+                            event.setLocation(event.getX(), mDispatchY);
+                            mDispatch = true;
+                            return mNotesListView.dispatchTouchEvent(event);
+                        }
+                    }
+                    break;     /*注释解释了点击“新建笔记”按钮透明部分时的逻辑；如果触摸点符合特定条件（即位于透明区域内），则获取列表视图的最后一个子视图；如果视图存在并且其位置符合特定范围，则修改事件位置，并将事件分发给列表视图*/
+                }
+                case MotionEvent.ACTION_MOVE: {
+                    if (mDispatch) {
+                        mDispatchY += (int) event.getY() - mOriginY;
+                        event.setLocation(event.getX(), mDispatchY);
+                        return mNotesListView.dispatchTouchEvent(event);
+                    }
+                    break;
+                }       /*当触摸事件为移动时，如果之前已经分发过事件，则更新分发的 Y 坐标，并再次分发事件给列表视图*/
+                default: {
+                    if (mDispatch) {
+                        event.setLocation(event.getX(), mDispatchY);
+                        mDispatch = false;
+                        return mNotesListView.dispatchTouchEvent(event);
+                    }
+                    break;
+                }
+            }
+            return false;
+        }       /*对于其他类型的触摸事件（例如抬起事件），如果之前有分发过事件，则重置分发标志，并分发事件给列表视图*/
+
+    };
+
+    private void startAsyncNotesListQuery() {
+        String selection = (mCurrentFolderId == Notes.ID_ROOT_FOLDER) ? ROOT_FOLDER_SELECTION
+                : NORMAL_SELECTION;
+        mBackgroundQueryHandler.startQuery(FOLDER_NOTE_LIST_QUERY_TOKEN, null,
+                Notes.CONTENT_NOTE_URI, NoteItemData.PROJECTION, selection, new String[] {
+                    String.valueOf(mCurrentFolderId)
+                }, NoteColumns.TYPE + " DESC," + NoteColumns.MODIFIED_DATE + " DESC");
+    }            /*定义了一个私有方法 startAsyncNotesListQuery 用于启动异步查询笔记列表的操作；根据当前文件夹 ID 设置查询条件；使用 AsyncQueryHandler 发起查询*/
+
+    private final class BackgroundQueryHandler extends AsyncQueryHandler {
+        public BackgroundQueryHandler(ContentResolver contentResolver) {
+            super(contentResolver);
+        }
+
+        @Override
+        protected void onQueryComplete(int token, Object cookie, Cursor cursor) {
+            switch (token) {
+                case FOLDER_NOTE_LIST_QUERY_TOKEN:
+                    mNotesListAdapter.changeCursor(cursor);
+                    break;
+                case FOLDER_LIST_QUERY_TOKEN:
+                    if (cursor != null && cursor.getCount() > 0) {
+                        showFolderListMenu(cursor);
+                    } else {
+                        Log.e(TAG, "Query folder failed");
+                    }
+                    break;
+                default:
+                    return;
+            }
+        }
+    }     /*定义了一个内部类 BackgroundQueryHandler 继承自 AsyncQueryHandler；覆盖了 onQueryComplete 方法，在查询完成后更新适配器的游标或显示文件夹列表菜单*/
+
+    private void showFolderListMenu(Cursor cursor) {
+        AlertDialog.Builder builder = new AlertDialog.Builder(NotesListActivity.this);
+        builder.setTitle(R.string.menu_title_select_folder);
+        final FoldersListAdapter adapter = new FoldersListAdapter(this, cursor);
+        builder.setAdapter(adapter, new DialogInterface.OnClickListener() {
+
+            public void onClick(DialogInterface dialog, int which) {
+                DataUtils.batchMoveToFolder(mContentResolver,
+                        mNotesListAdapter.getSelectedItemIds(), adapter.getItemId(which));
+                Toast.makeText(
+                        NotesListActivity.this,
+                        getString(R.string.format_move_notes_to_folder,
+                                mNotesListAdapter.getSelectedCount(),
+                                adapter.getFolderName(NotesListActivity.this, which)),
+                        Toast.LENGTH_SHORT).show();
+                mModeCallBack.finishActionMode();
+            }
+        });
+        builder.show();
+    }             /*定义了一个私有方法 showFolderListMenu 用于显示一个对话框供用户选择要移动笔记的目标文件夹；当用户选择文件夹后，批量移动笔记，并显示一个提示信息，最后结束多选模式*/
+
+    private void createNewNote() {
+        Intent intent = new Intent(this, NoteEditActivity.class);
+        intent.setAction(Intent.ACTION_INSERT_OR_EDIT);
+        intent.putExtra(Notes.INTENT_EXTRA_FOLDER_ID, mCurrentFolderId);
+        this.startActivityForResult(intent, REQUEST_CODE_NEW_NODE);
+    }         /*定义了一个私有方法 createNewNote 用于创建一个新的笔记；启动一个编辑笔记的活动，并传递当前文件夹 ID 作为额外数据*/
+
+    private void batchDelete() {
+        new AsyncTask<Void, Void, HashSet<AppWidgetAttribute>>() {
+            protected HashSet<AppWidgetAttribute> doInBackground(Void... unused) {
+                HashSet<AppWidgetAttribute> widgets = mNotesListAdapter.getSelectedWidget();
+                if (!isSyncMode()) {
+                    // if not synced, delete notes directly
+                    if (DataUtils.batchDeleteNotes(mContentResolver, mNotesListAdapter
+                            .getSelectedItemIds())) {
+                    } else {
+                        Log.e(TAG, "Delete notes error, should not happens");
+                    }
+                } else {
+                    // in sync mode, we'll move the deleted note into the trash
+                    // folder
+                    if (!DataUtils.batchMoveToFolder(mContentResolver, mNotesListAdapter
+                            .getSelectedItemIds(), Notes.ID_TRASH_FOLER)) {
+                        Log.e(TAG, "Move notes to trash folder error, should not happens");
+                    }
+                }
+                return widgets;
+            }        /*定义了一个私有方法 batchDelete 用于批量删除笔记；使用 AsyncTask 异步执行删除或移动笔记的操作；根据是否处于同步模式决定是直接删除还是移到回收站文件夹*/
+
+            @Override
+            protected void onPostExecute(HashSet<AppWidgetAttribute> widgets) {
+                if (widgets != null) {
+                    for (AppWidgetAttribute widget : widgets) {
+                        if (widget.widgetId != AppWidgetManager.INVALID_APPWIDGET_ID
+                                && widget.widgetType != Notes.TYPE_WIDGET_INVALIDE) {
+                            updateWidget(widget.widgetId, widget.widgetType);
+                        }
+                    }
+                }
+                mModeCallBack.finishActionMode();
+            }
+        }.execute();   /*在异步任务完成后，如果获得了有效的小部件集合，则更新每个小部件，并结束多选模式*/
+    }
+
+    private void deleteFolder(long folderId) {
+        if (folderId == Notes.ID_ROOT_FOLDER) {
+            Log.e(TAG, "Wrong folder id, should not happen " + folderId);
+            return;
+        }
+
+        HashSet<Long> ids = new HashSet<Long>();
+        ids.add(folderId);
+        HashSet<AppWidgetAttribute> widgets = DataUtils.getFolderNoteWidget(mContentResolver,
+                folderId);
+        if (!isSyncMode()) {
+            // if not synced, delete folder directly
+            DataUtils.batchDeleteNotes(mContentResolver, ids);
+        } else {
+            // in sync mode, we'll move the deleted folder into the trash folder
+            DataUtils.batchMoveToFolder(mContentResolver, ids, Notes.ID_TRASH_FOLER);
+        }
+        if (widgets != null) {
+            for (AppWidgetAttribute widget : widgets) {
+                if (widget.widgetId != AppWidgetManager.INVALID_APPWIDGET_ID
+                        && widget.widgetType != Notes.TYPE_WIDGET_INVALIDE) {
+                    updateWidget(widget.widgetId, widget.widgetType);
+                }
+            }
+        }
+    }          /*定义了一个私有方法 deleteFolder 用于删除文件夹；首先检查文件夹 ID 是否有效；获取文件夹关联的小部件；根据同步模式决定删除还是移至回收站；如果有相关小部件，则更新它们*/
+
+    private void openNode(NoteItemData data) {
+        Intent intent = new Intent(this, NoteEditActivity.class);
+        intent.setAction(Intent.ACTION_VIEW);
+        intent.putExtra(Intent.EXTRA_UID, data.getId());
+        this.startActivityForResult(intent, REQUEST_CODE_OPEN_NODE);
+    }         /*定义了一个私有方法 openNode 用于打开笔记；启动一个编辑笔记的活动，并传递笔记 ID 作为额外数据*/
+
+    private void openFolder(NoteItemData data) {
+        mCurrentFolderId = data.getId();
+        startAsyncNotesListQuery();
+        if (data.getId() == Notes.ID_CALL_RECORD_FOLDER) {
+            mState = ListEditState.CALL_RECORD_FOLDER;
+            mAddNewNote.setVisibility(View.GONE);
+        } else {
+            mState = ListEditState.SUB_FOLDER;
+        }
+        if (data.getId() == Notes.ID_CALL_RECORD_FOLDER) {
+            mTitleBar.setText(R.string.call_record_folder_name);
+        } else {
+            mTitleBar.setText(data.getSnippet());
+        }
+        mTitleBar.setVisibility(View.VISIBLE);
+    }         /*定义了一个私有方法 openFolder 用于打开文件夹；设置当前文件夹 ID 并重新查询笔记列表；根据文件夹类型设置状态、标题栏文本和可见性*/
+
+    public void onClick(View v) {
+        switch (v.getId()) {
+            case R.id.btn_new_note:
+                createNewNote();
+                break;
+            default:
+                break;
+        }
+    }      /*定义了一个公共方法 onClick 处理点击事件；如果点击的是“新建笔记”按钮，则创建新笔记*/
+
+    private void showSoftInput() {
+        InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
+        if (inputMethodManager != null) {
+            inputMethodManager.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0);
+        }
+    }     /*定义了一个私有方法 showSoftInput 用于显示软键盘*/
+
+    private void hideSoftInput(View view) {
+        InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
+        inputMethodManager.hideSoftInputFromWindow(view.getWindowToken(), 0);
+    }        /*定义了一个私有方法 hideSoftInput 用于隐藏软键盘*/
+
+    private void showCreateOrModifyFolderDialog(final boolean create) {
+        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        View view = LayoutInflater.from(this).inflate(R.layout.dialog_edit_text, null);
+        final EditText etName = (EditText) view.findViewById(R.id.et_foler_name);
+        showSoftInput();
+        if (!create) {
+            if (mFocusNoteDataItem != null) {
+                etName.setText(mFocusNoteDataItem.getSnippet());
+                builder.setTitle(getString(R.string.menu_folder_change_name));
+            } else {
+                Log.e(TAG, "The long click data item is null");
+                return;
+            }
+        } else {
+            etName.setText("");
+            builder.setTitle(this.getString(R.string.menu_create_folder));
+        }
+
+        builder.setPositiveButton(android.R.string.ok, null);
+        builder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
+            public void onClick(DialogInterface dialog, int which) {
+                hideSoftInput(etName);
+            }
+        });
+
+        final Dialog dialog = builder.setView(view).show();
+        final Button positive = (Button)dialog.findViewById(android.R.id.button1);
+        positive.setOnClickListener(new OnClickListener() {
+            public void onClick(View v) {
+                hideSoftInput(etName);
+                String name = etName.getText().toString();
+                if (DataUtils.checkVisibleFolderName(mContentResolver, name)) {
+                    Toast.makeText(NotesListActivity.this, getString(R.string.folder_exist, name),
+                            Toast.LENGTH_LONG).show();
+                    etName.setSelection(0, etName.length());
+                    return;
+                }
+                if (!create) {
+                    if (!TextUtils.isEmpty(name)) {
+                        ContentValues values = new ContentValues();
+                        values.put(NoteColumns.SNIPPET, name);
+                        values.put(NoteColumns.TYPE, Notes.TYPE_FOLDER);
+                        values.put(NoteColumns.LOCAL_MODIFIED, 1);
+                        mContentResolver.update(Notes.CONTENT_NOTE_URI, values, NoteColumns.ID
+                                + "=?", new String[] {
+                            String.valueOf(mFocusNoteDataItem.getId())
+                        });
+                    }
+                } else if (!TextUtils.isEmpty(name)) {
+                    ContentValues values = new ContentValues();
+                    values.put(NoteColumns.SNIPPET, name);
+                    values.put(NoteColumns.TYPE, Notes.TYPE_FOLDER);
+                    mContentResolver.insert(Notes.CONTENT_NOTE_URI, values);
+                }
+                dialog.dismiss();
+            }
+        });
+
+        if (TextUtils.isEmpty(etName.getText())) {
+            positive.setEnabled(false);
+        }
+        /**
+         * When the name edit text is null, disable the positive button
+         */
+        etName.addTextChangedListener(new TextWatcher() {
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
+                // TODO Auto-generated method stub
+
+            }
+
+            public void onTextChanged(CharSequence s, int start, int before, int count) {
+                if (TextUtils.isEmpty(etName.getText())) {
+                    positive.setEnabled(false);
+                } else {
+                    positive.setEnabled(true);
+                }
+            }
+
+            public void afterTextChanged(Editable s) {
+                // TODO Auto-generated method stub
+
+            }
+        });
+    }          /*定义了一个私有方法 showCreateOrModifyFolderDialog 用于显示创建或修改文件夹的对话框；根据是否为创建模式设置初始文本和对话框标题；设置确定和取消按钮的行为；监听名称输入框的变化以启用或禁用确定按钮*/
+
+    @Override
+    public void onBackPressed() {
+        switch (mState) {
+            case SUB_FOLDER:
+                mCurrentFolderId = Notes.ID_ROOT_FOLDER;
+                mState = ListEditState.NOTE_LIST;
+                startAsyncNotesListQuery();
+                mTitleBar.setVisibility(View.GONE);
+                break;
+            case CALL_RECORD_FOLDER:
+                mCurrentFolderId = Notes.ID_ROOT_FOLDER;
+                mState = ListEditState.NOTE_LIST;
+                mAddNewNote.setVisibility(View.VISIBLE);
+                mTitleBar.setVisibility(View.GONE);
+                startAsyncNotesListQuery();
+                break;
+            case NOTE_LIST:
+                super.onBackPressed();
+                break;
+            default:
+                break;
+        }
+    }     /*重写 onBackPressed() 方法来处理应用内的导航。根据当前状态返回到父目录或者默认行为*/
+
+    private void updateWidget(int appWidgetId, int appWidgetType) {
+        Intent intent = new Intent(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
+        if (appWidgetType == Notes.TYPE_WIDGET_2X) {
+            intent.setClass(this, NoteWidgetProvider_2x.class);
+        } else if (appWidgetType == Notes.TYPE_WIDGET_4X) {
+            intent.setClass(this, NoteWidgetProvider_4x.class);
+        } else {
+            Log.e(TAG, "Unspported widget type");
+            return;
+        }
+
+        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, new int[] {
+            appWidgetId
+        });
+
+        sendBroadcast(intent);
+        setResult(RESULT_OK, intent);
+    }          /*定义了一个方法 updateWidget 来更新不同类型的桌面小部件。它通过广播Intent来通知系统更新指定ID的小部件*/
+
+    private final OnCreateContextMenuListener mFolderOnCreateContextMenuListener = new OnCreateContextMenuListener() {
+        public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
+            if (mFocusNoteDataItem != null) {
+                menu.setHeaderTitle(mFocusNoteDataItem.getSnippet());
+                menu.add(0, MENU_FOLDER_VIEW, 0, R.string.menu_folder_view);
+                menu.add(0, MENU_FOLDER_DELETE, 0, R.string.menu_folder_delete);
+                menu.add(0, MENU_FOLDER_CHANGE_NAME, 0, R.string.menu_folder_change_name);
+            }
+        }
+    };    /*定义了一个内部类 mFolderOnCreateContextMenuListener 用来创建上下文菜单，当用户长按某个项目时显示查看、删除和重命名的选项*/
+
+    @Override
+    public void onContextMenuClosed(Menu menu) {
+        if (mNotesListView != null) {
+            mNotesListView.setOnCreateContextMenuListener(null);
+        }
+        super.onContextMenuClosed(menu);
+    }        /*重写 onContextMenuClosed() 方法，在上下文菜单关闭后清除设置的上下文菜单监听器*/
+
+    @Override
+    public boolean onContextItemSelected(MenuItem item) {
+        if (mFocusNoteDataItem == null) {
+            Log.e(TAG, "The long click data item is null");
+            return false;
+        }
+        switch (item.getItemId()) {
+            case MENU_FOLDER_VIEW:
+                openFolder(mFocusNoteDataItem);
+                break;
+            case MENU_FOLDER_DELETE:
+                AlertDialog.Builder builder = new AlertDialog.Builder(this);
+                builder.setTitle(getString(R.string.alert_title_delete));
+                builder.setIcon(android.R.drawable.ic_dialog_alert);
+                builder.setMessage(getString(R.string.alert_message_delete_folder));
+                builder.setPositiveButton(android.R.string.ok,
+                        new DialogInterface.OnClickListener() {
+                            public void onClick(DialogInterface dialog, int which) {
+                                deleteFolder(mFocusNoteDataItem.getId());
+                            }
+                        });
+                builder.setNegativeButton(android.R.string.cancel, null);
+                builder.show();
+                break;
+            case MENU_FOLDER_CHANGE_NAME:
+                showCreateOrModifyFolderDialog(false);
+                break;
+            default:
+                break;
+        }
+
+        return true;
+    }       /*重写 onContextItemSelected() 方法来处理用户从上下文菜单中选择的项，比如打开文件夹、删除文件夹或更改文件夹名称*/
+
+    @Override
+    public boolean onPrepareOptionsMenu(Menu menu) {
+        menu.clear();
+        if (mState == ListEditState.NOTE_LIST) {
+            getMenuInflater().inflate(R.menu.note_list, menu);
+            // set sync or sync_cancel
+            menu.findItem(R.id.menu_sync).setTitle(
+                    GTaskSyncService.isSyncing() ? R.string.menu_sync_cancel : R.string.menu_sync);
+        } else if (mState == ListEditState.SUB_FOLDER) {
+            getMenuInflater().inflate(R.menu.sub_folder, menu);
+        } else if (mState == ListEditState.CALL_RECORD_FOLDER) {
+            getMenuInflater().inflate(R.menu.call_record_folder, menu);
+        } else {
+            Log.e(TAG, "Wrong state:" + mState);
+        }
+        return true;
+    }       /*重写 onPrepareOptionsMenu() 方法来准备选项菜单。根据当前的状态加载不同的菜单布局，并且设置同步项的标题*/
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        switch (item.getItemId()) {
+            case R.id.menu_new_folder: {
+                showCreateOrModifyFolderDialog(true);
+                break;
+            }
+            case R.id.menu_export_text: {
+                exportNoteToText();
+                break;
+            }
+            case R.id.menu_sync: {
+                if (isSyncMode()) {
+                    if (TextUtils.equals(item.getTitle(), getString(R.string.menu_sync))) {
+                        GTaskSyncService.startSync(this);
+                    } else {
+                        GTaskSyncService.cancelSync(this);
+                    }
+                } else {
+                    startPreferenceActivity();
+                }
+                break;
+            }
+            case R.id.menu_setting: {
+                startPreferenceActivity();
+                break;
+            }
+            case R.id.menu_new_note: {
+                createNewNote();
+                break;
+            }
+            case R.id.menu_search:
+                onSearchRequested();
+                break;
+            default:
+                break;
+        }
+        return true;
+    }       /*重写 onOptionsItemSelected() 方法来处理菜单项的点击事件，如创建新文件夹、导出笔记为文本、开始或停止同步服务、打开设置界面、创建新笔记和触发搜索等操作*/
+
+    @Override
+    public boolean onSearchRequested() {
+        startSearch(null, false, null /* appData */, false);
+        return true;
+    }    /*此方法重写了 onSearchRequested()，当用户触发搜索时，使用 startSearch 方法开始搜索，参数表示不使用已有的搜索字符串、不重新聚焦搜索框、不传递应用数据以及不启动新的搜索*/
+
+    private void exportNoteToText() {
+        final BackupUtils backup = BackupUtils.getInstance(NotesListActivity.this);
+        new AsyncTask<Void, Void, Integer>() {
+
+            @Override
+            protected Integer doInBackground(Void... unused) {
+                return backup.exportToText();
+            }
+
+            @Override
+            protected void onPostExecute(Integer result) {
+                if (result == BackupUtils.STATE_SD_CARD_UNMOUONTED) {
+                    AlertDialog.Builder builder = new AlertDialog.Builder(NotesListActivity.this);
+                    builder.setTitle(NotesListActivity.this
+                            .getString(R.string.failed_sdcard_export));
+                    builder.setMessage(NotesListActivity.this
+                            .getString(R.string.error_sdcard_unmounted));
+                    builder.setPositiveButton(android.R.string.ok, null);
+                    builder.show();
+                } else if (result == BackupUtils.STATE_SUCCESS) {
+                    AlertDialog.Builder builder = new AlertDialog.Builder(NotesListActivity.this);
+                    builder.setTitle(NotesListActivity.this
+                            .getString(R.string.success_sdcard_export));
+                    builder.setMessage(NotesListActivity.this.getString(
+                            R.string.format_exported_file_location, backup
+                                    .getExportedTextFileName(), backup.getExportedTextFileDir()));
+                    builder.setPositiveButton(android.R.string.ok, null);
+                    builder.show();
+                } else if (result == BackupUtils.STATE_SYSTEM_ERROR) {
+                    AlertDialog.Builder builder = new AlertDialog.Builder(NotesListActivity.this);
+                    builder.setTitle(NotesListActivity.this
+                            .getString(R.string.failed_sdcard_export));
+                    builder.setMessage(NotesListActivity.this
+                            .getString(R.string.error_sdcard_export));
+                    builder.setPositiveButton(android.R.string.ok, null);
+                    builder.show();
+                }
+            }
+
+        }.execute();
+    }     /*此方法用于将笔记导出为文本文件。它首先获取 BackupUtils 实例，然后使用异步任务（AsyncTask）来执行导出操作。根据导出结果的不同，会显示相应的对话框告知用户导出的状态*/
+
+    private boolean isSyncMode() {
+        return NotesPreferenceActivity.getSyncAccountName(this).trim().length() > 0;
+    }  /*检查是否设置了同步账户名来判断是否处于同步模式*/
+
+    private void startPreferenceActivity() {
+        Activity from = getParent() != null ? getParent() : this;
+        Intent intent = new Intent(from, NotesPreferenceActivity.class);
+        from.startActivityIfNeeded(intent, -1);
+    }     /*此方法用于启动偏好设置活动（NotesPreferenceActivity），允许用户配置应用设置*/
+
+    private class OnListItemClickListener implements OnItemClickListener {
+
+        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
+            if (view instanceof NotesListItem) {
+                NoteItemData item = ((NotesListItem) view).getItemData();
+                if (mNotesListAdapter.isInChoiceMode()) {
+                    if (item.getType() == Notes.TYPE_NOTE) {
+                        position = position - mNotesListView.getHeaderViewsCount();
+                        mModeCallBack.onItemCheckedStateChanged(null, position, id,
+                                !mNotesListAdapter.isSelectedItem(position));
+                    }
+                    return;
+                }
+
+                switch (mState) {
+                    case NOTE_LIST:
+                        if (item.getType() == Notes.TYPE_FOLDER
+                                || item.getType() == Notes.TYPE_SYSTEM) {
+                            openFolder(item);
+                        } else if (item.getType() == Notes.TYPE_NOTE) {
+                            openNode(item);
+                        } else {
+                            Log.e(TAG, "Wrong note type in NOTE_LIST");
+                        }
+                        break;
+                    case SUB_FOLDER:
+                    case CALL_RECORD_FOLDER:
+                        if (item.getType() == Notes.TYPE_NOTE) {
+                            openNode(item);
+                        } else {
+                            Log.e(TAG, "Wrong note type in SUB_FOLDER");
+                        }
+                        break;
+                    default:
+                        break;
+                }
+            }
+        }
+
+    }    /*这是一个内部类，实现了 OnItemClickListener 接口，用于处理列表项被点击时的行为。根据当前的状态和点击的条目类型，可能会打开一个文件夹或笔记*/
+
+    private void startQueryDestinationFolders() {
+        String selection = NoteColumns.TYPE + "=? AND " + NoteColumns.PARENT_ID + "<>? AND " + NoteColumns.ID + "<>?";
+        selection = (mState == ListEditState.NOTE_LIST) ? selection:
+            "(" + selection + ") OR (" + NoteColumns.ID + "=" + Notes.ID_ROOT_FOLDER + ")";
+
+        mBackgroundQueryHandler.startQuery(FOLDER_LIST_QUERY_TOKEN,
+                null,
+                Notes.CONTENT_NOTE_URI,
+                FoldersListAdapter.PROJECTION,
+                selection,
+                new String[] {
+                        String.valueOf(Notes.TYPE_FOLDER),
+                        String.valueOf(Notes.ID_TRASH_FOLER),
+                        String.valueOf(mCurrentFolderId)
+                },
+                NoteColumns.MODIFIED_DATE + " DESC");
+    }    /*此方法用于启动查询以获取目的地文件夹的列表。它构建了一个SQL查询语句，并使用 ContentResolver 的 startQuery 方法来执行查询*/
+
+    public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
+        if (view instanceof NotesListItem) {
+            mFocusNoteDataItem = ((NotesListItem) view).getItemData();
+            if (mFocusNoteDataItem.getType() == Notes.TYPE_NOTE && !mNotesListAdapter.isInChoiceMode()) {
+                if (mNotesListView.startActionMode(mModeCallBack) != null) {
+                    mModeCallBack.onItemCheckedStateChanged(null, position, id, true);
+                    mNotesListView.performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
+                } else {
+                    Log.e(TAG, "startActionMode fails");
+                }
+            } else if (mFocusNoteDataItem.getType() == Notes.TYPE_FOLDER) {
+                mNotesListView.setOnCreateContextMenuListener(mFolderOnCreateContextMenuListener);
+            }
+        }
+        return false;
+    }
+}   /*此方法处理列表项的长按事件。如果长按的是一个笔记并且不在选择模式下，则启动选择模式并选择该笔记；如果是文件夹，则设置一个上下文菜单监听器以便在用户进一步操作时显示上下文菜单*/

NotesListAdapter.java

@@ -0,0 +1,187 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+/*这段代码展示了一个自定义的 CursorAdapter 类 NotesListAdapter 的实现，主要用于显示一个包含笔记列表的适配器。这个适配器支持选择模式（choice mode），允许用户多选笔记条目进行批量操作。*/
+
+package net.micode.notes.ui;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.util.Log;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.CursorAdapter;
+
+import net.micode.notes.data.Notes;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+
+
+public class NotesListAdapter extends CursorAdapter {
+    private static final String TAG = "NotesListAdapter";
+    private Context mContext;
+    private HashMap<Integer, Boolean> mSelectedIndex;
+    private int mNotesCount;
+    private boolean mChoiceMode;
+
+    public static class AppWidgetAttribute {
+        public int widgetId;
+        public int widgetType;
+    };
+
+    public NotesListAdapter(Context context) {
+        super(context, null);
+        mSelectedIndex = new HashMap<Integer, Boolean>();
+        mContext = context;
+        mNotesCount = 0;
+    }          /*构造函数初始化了适配器的基本属性，包括上下文、存储选定索引的哈希表和笔记数量*/
+
+    @Override
+    public View newView(Context context, Cursor cursor, ViewGroup parent) {
+        return new NotesLis tItem(context);
+    }    /*此方法负责创建一个新的视图，这里返回的是一个 NotesListItem 视图对象*/
+
+    @Override
+    public void bindView(View view, Context context, Cursor cursor) {
+        if (view instanceof NotesListItem) {
+            NoteItemData itemData = new NoteItemData(context, cursor);
+            ((NotesListItem) view).bind(context, itemData, mChoiceMode,
+                    isSelectedItem(cursor.getPosition()));
+        }
+    }     /*此方法用于绑定数据到视图。这里将从 Cursor 中获取的数据绑定到 NotesListItem 对象上，并设置选择模式和当前项是否被选中*/
+
+    public void setCheckedItem(final int position, final boolean checked) {
+        mSelectedIndex.put(position, checked);
+        notifyDataSetChanged();
+    }
+
+    public boolean isInChoiceMode() {
+        return mChoiceMode;
+    }     /*这两个方法分别用于设置选择模式和检查当前是否处于选择模式*/
+
+    public void setChoiceMode(boolean mode) {
+        mSelectedIndex.clear();
+        mChoiceMode = mode;
+    }
+
+    public void selectAll(boolean checked) {
+        Cursor cursor = getCursor();
+        for (int i = 0; i < getCount(); i++) {
+            if (cursor.moveToPosition(i)) {
+                if (NoteItemData.getNoteType(cursor) == Notes.TYPE_NOTE) {
+                    setCheckedItem(i, checked);
+                }
+            }
+        }
+    }     /*此方法遍历所有的笔记，并根据传入的布尔值设置所有笔记项为选中或取消选中*/
+
+    public HashSet<Long> getSelectedItemIds() {
+        HashSet<Long> itemSet = new HashSet<Long>();
+        for (Integer position : mSelectedIndex.keySet()) {
+            if (mSelectedIndex.get(position) == true) {
+                Long id = getItemId(position);
+                if (id == Notes.ID_ROOT_FOLDER) {
+                    Log.d(TAG, "Wrong item id, should not happen");
+                } else {
+                    itemSet.add(id);
+                }
+            }
+        }
+
+        return itemSet;
+    }       /*此方法返回一个包含所有被选中项ID的集合*/
+
+    public HashSet<AppWidgetAttribute> getSelectedWidget() {
+        HashSet<AppWidgetAttribute> itemSet = new HashSet<AppWidgetAttribute>();
+        for (Integer position : mSelectedIndex.keySet()) {
+            if (mSelectedIndex.get(position) == true) {
+                Cursor c = (Cursor) getItem(position);
+                if (c != null) {
+                    AppWidgetAttribute widget = new AppWidgetAttribute();
+                    NoteItemData item = new NoteItemData(mContext, c);
+                    widget.widgetId = item.getWidgetId();
+                    widget.widgetType = item.getWidgetType();
+                    itemSet.add(widget);
+                    /**
+                     * Don't close cursor here, only the adapter could close it
+                     */
+                } else {
+                    Log.e(TAG, "Invalid cursor");
+                    return null;
+                }
+            }
+        }
+        return itemSet;
+    }       /*此方法返回一个包含所有被选中小部件属性的集合*/
+
+    public int getSelectedCount() {
+        Collection<Boolean> values = mSelectedIndex.values();
+        if (null == values) {
+            return 0;
+        }
+        Iterator<Boolean> iter = values.iterator();
+        int count = 0;
+        while (iter.hasNext()) {
+            if (true == iter.next()) {
+                count++;
+            }
+        }
+        return count;
+    }     /*此方法计算并返回被选中项的数量*/
+
+    public boolean isAllSelected() {
+        int checkedCount = getSelectedCount();
+        return (checkedCount != 0 && checkedCount == mNotesCount);
+    }     /*此方法用于检查当前是否所有的笔记都被选中*/
+
+    public boolean isSelectedItem(final int position) {
+        if (null == mSelectedIndex.get(position)) {
+            return false;
+        }
+        return mSelectedIndex.get(position);
+    }     /*setCheckedItem 方法用于设置指定位置的项是否被选中，并通知适配器数据已改变。isSelectedItem 方法则用于检查指定位置的项是否已被选中*/
+
+    @Override
+    protected void onContentChanged() {
+        super.onContentChanged();
+        calcNotesCount();
+    }
+
+    @Override
+    public void changeCursor(Cursor cursor) {
+        super.changeCursor(cursor);
+        calcNotesCount();
+    }
+
+    private void calcNotesCount() {
+        mNotesCount = 0;
+        for (int i = 0; i < getCount(); i++) {
+            Cursor c = (Cursor) getItem(i);
+            if (c != null) {
+                if (NoteItemData.getNoteType(c) == Notes.TYPE_NOTE) {
+                    mNotesCount++;
+                }
+            } else {
+                Log.e(TAG, "Invalid cursor");
+                return;
+            }
+        }
+    }
+}       /*此方法用于计算笔记的数量，只统计类型为 Notes.TYPE_NOTE 的条目*/

NotesListItem.java

@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+/*这段代码展示了 NotesListItem 类的实现，它是 Android 应用程序中的一个自定义视图，用于显示笔记列表中的单个条目*/
+
+
+package net.micode.notes.ui;
+
+import android.content.Context;
+import android.text.format.DateUtils;
+import android.view.View;
+import android.widget.CheckBox;
+import android.widget.ImageView;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.tool.DataUtils;
+import net.micode.notes.tool.ResourceParser.NoteItemBgResources;
+
+
+public class NotesListItem extends LinearLayout {
+    private ImageView mAlert;
+    private TextView mTitle;
+    private TextView mTime;
+    private TextView mCallName;
+    private NoteItemData mItemData;
+    private CheckBox mCheckBox;
+
+    public NotesListItem(Context context) {
+        super(context);
+        inflate(context, R.layout.note_item, this);
+        mAlert = (ImageView) findViewById(R.id.iv_alert_icon);
+        mTitle = (TextView) findViewById(R.id.tv_title);
+        mTime = (TextView) findViewById(R.id.tv_time);
+        mCallName = (TextView) findViewById(R.id.tv_name);
+        mCheckBox = (CheckBox) findViewById(android.R.id.checkbox);
+    }     /*构造函数初始化了一个 LinearLayout 并且使用 inflate 方法加载了布局文件 note_item。此外，还初始化了与笔记条目相关的各个控件，例如图标、标题、时间和复选框等*/
+
+    public void bind(Context context, NoteItemData data, boolean choiceMode, boolean checked) {
+        if (choiceMode && data.getType() == Notes.TYPE_NOTE) {
+            mCheckBox.setVisibility(View.VISIBLE);
+            mCheckBox.setChecked(checked);
+        } else {
+            mCheckBox.setVisibility(View.GONE);
+        }
+
+        mItemData = data;
+        if (data.getId() == Notes.ID_CALL_RECORD_FOLDER) {
+            mCallName.setVisibility(View.GONE);
+            mAlert.setVisibility(View.VISIBLE);
+            mTitle.setTextAppearance(context, R.style.TextAppearancePrimaryItem);
+            mTitle.setText(context.getString(R.string.call_record_folder_name)
+                    + context.getString(R.string.format_folder_files_count, data.getNotesCount()));
+            mAlert.setImageResource(R.drawable.call_record);
+        } else if (data.getParentId() == Notes.ID_CALL_RECORD_FOLDER) {
+            mCallName.setVisibility(View.VISIBLE);
+            mCallName.setText(data.getCallName());
+            mTitle.setTextAppearance(context,R.style.TextAppearanceSecondaryItem);
+            mTitle.setText(DataUtils.getFormattedSnippet(data.getSnippet()));
+            if (data.hasAlert()) {
+                mAlert.setImageResource(R.drawable.clock);
+                mAlert.setVisibility(View.VISIBLE);
+            } else {
+                mAlert.setVisibility(View.GONE);
+            }
+        } else {
+            mCallName.setVisibility(View.GONE);
+            mTitle.setTextAppearance(context, R.style.TextAppearancePrimaryItem);
+
+            if (data.getType() == Notes.TYPE_FOLDER) {
+                mTitle.setText(data.getSnippet()
+                        + context.getString(R.string.format_folder_files_count,
+                                data.getNotesCount()));
+                mAlert.setVisibility(View.GONE);
+            } else {
+                mTitle.setText(DataUtils.getFormattedSnippet(data.getSnippet()));
+                if (data.hasAlert()) {
+                    mAlert.setImageResource(R.drawable.clock);
+                    mAlert.setVisibility(View.VISIBLE);
+                } else {
+                    mAlert.setVisibility(View.GONE);
+                }
+            }
+        }
+        mTime.setText(DateUtils.getRelativeTimeSpanString(data.getModifiedDate()));
+
+        setBackground(data);
+    }
+
+    /*绑定数据
+    此方法用于将数据绑定到视图组件上。它接收四个参数：
+    context：当前上下文。
+    data：包含条目信息的 NoteItemData 对象。
+    choiceMode：指示当前是否处于选择模式。
+    checked：指示当前条目是否被选中。
+    方法根据不同的条件设置视图的可见性、文本、背景图像等属性。例如，如果当前是选择模式且条目类型为笔记，则显示复选框并设置其状态。对于不同类型的笔记（文件夹、通话记录等），设置不同的标题文本和图标。最后，更新条目的修改时间显示。*/
+
+
+    private void setBackground(NoteItemData data) {
+        int id = data.getBgColorId();
+        if (data.getType() == Notes.TYPE_NOTE) {
+            if (data.isSingle() || data.isOneFollowingFolder()) {
+                setBackgroundResource(NoteItemBgResources.getNoteBgSingleRes(id));
+            } else if (data.isLast()) {
+                setBackgroundResource(NoteItemBgResources.getNoteBgLastRes(id));
+            } else if (data.isFirst() || data.isMultiFollowingFolder()) {
+                setBackgroundResource(NoteItemBgResources.getNoteBgFirstRes(id));
+            } else {
+                setBackgroundResource(NoteItemBgResources.getNoteBgNormalRes(id));
+            }
+        } else {
+            setBackgroundResource(NoteItemBgResources.getFolderBgRes());
+        }
+    }
+
+    /*设置背景
+    此方法根据条目的类型和特性来设置条目的背景。对于笔记，根据是否是单个、最后一个、第一个还是多个中间的一个来设置不同的背景资源。对于文件夹，设置统一的文件夹背景资源*/
+
+
+    public NoteItemData getItemData() {
+        return mItemData;
+    }
+}   /*此方法返回当前绑定到该视图的 NoteItemData 对象，使得其他组件可以通过这个方法获取条目的数据*/

NotesPreferenceActivity.java

@@ -0,0 +1,388 @@
+/*
+ * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.ui;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.app.ActionBar;
+import android.app.AlertDialog;
+import android.content.BroadcastReceiver;
+import android.content.ContentValues;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.SharedPreferences;
+import android.os.Bundle;
+import android.preference.Preference;
+import android.preference.Preference.OnPreferenceClickListener;
+import android.preference.PreferenceActivity;
+import android.preference.PreferenceCategory;
+import android.text.TextUtils;
+import android.text.format.DateFormat;
+import android.view.LayoutInflater;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.view.View;
+import android.widget.Button;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.data.Notes.NoteColumns;
+import net.micode.notes.gtask.remote.GTaskSyncService;
+
+
+public class NotesPreferenceActivity extends PreferenceActivity {  /*定义一个名为 NotesPreferenceActivity 的类，继承自 PreferenceActivity*/
+    public static final String PREFERENCE_NAME = "notes_preferences";  /*定义一个常量，表示偏好设置的名字*/
+
+    public static final String PREFERENCE_SYNC_ACCOUNT_NAME = "pref_key_account_name";  /*定义一个常量，表示用于保存同步账户名字的偏好设置键值*/
+
+    public static final String PREFERENCE_LAST_SYNC_TIME = "pref_last_sync_time";   /*定义一个常量，表示用于保存上次同步时间的偏好设置键值*/
+
+    public static final String PREFERENCE_SET_BG_COLOR_KEY = "pref_key_bg_random_appear";  /*定义一个常量，表示用于设置背景颜色的偏好设置键值*/
+
+    private static final String PREFERENCE_SYNC_ACCOUNT_KEY = "pref_sync_account_key";  /*定义一个常量，表示用于组织账户相关的偏好设置项的键值*/
+
+    private static final String AUTHORITIES_FILTER_KEY = "authorities";
+
+    private PreferenceCategory mAccountCategory;   /*定义一个 PreferenceCategory 类型的成员变量，用于组织账户相关的偏好设置项*/
+
+    private GTaskReceiver mReceiver;   /*定义一个 GTaskReceiver 类型的成员变量，用于接收广播*/
+
+    private Account[] mOriAccounts;   /*定义一个 Account 数组类型的成员变量，用于存储原始账户列表*/
+
+    private boolean mHasAddedAccount;   /*定义一个布尔类型的成员变量，用于标记是否已经添加过账户*/
+
+    @Override
+    protected void onCreate(Bundle icicle) {     /*重写 onCreate 方法，当 Activity 被创建时调用*/
+        super.onCreate(icicle);   /*调用父类的 onCreate 方法*/
+
+        /* using the app icon for navigation */
+        getActionBar().setDisplayHomeAsUpEnabled(true);   /*获取 ActionBar 并设置返回按钮显示应用图标*/
+
+        addPreferencesFromResource(R.xml.preferences);    /*从指定的 XML 文件中加载偏好设置*/
+        mAccountCategory = (PreferenceCategory) findPreference(PREFERENCE_SYNC_ACCOUNT_KEY);/*查找 PreferenceCategory 类型的偏好设置项，并赋值给 mAccountCategory 成员变量*/
+        mReceiver = new GTaskReceiver();   /*创建 GTaskReceiver 类型的对象*/
+        IntentFilter filter = new IntentFilter();  /*创建 IntentFilter 对象*/
+        filter.addAction(GTaskSyncService.GTASK_SERVICE_BROADCAST_NAME);  /*向 IntentFilter 中添加动作，用于接收特定广播*/
+        registerReceiver(mReceiver, filter);    /*注册 BroadcastReceiver，接收指定的动作广播*/
+
+        mOriAccounts = null;    /*初始化 mOriAccounts 为空*/
+        View header = LayoutInflater.from(this).inflate(R.layout.settings_header, null);  /*使用 LayoutInflater 加载头部布局*/
+        getListView().addHeaderView(header, null, true);   /*向 ListView 中添加头部视图*/
+    }    
+
+    @Override
+    protected void onResume() {  /*重写 onResume 方法，当 Activity 从不可见变为可见时调用*/
+        super.onResume();   /*调用父类的 onResume 方法*/
+
+        // need to set sync account automatically if user has added a new
+        // account
+        if (mHasAddedAccount) {   /*检查是否已经添加过账户*/
+            Account[] accounts = getGoogleAccounts();   /*获取设备上的所有 Google 账户*/
+            if (mOriAccounts != null && accounts.length > mOriAccounts.length) {   /*比较当前账户数量是否多于之前记录的数量*/
+                for (Account accountNew : accounts) {  /*遍历新的账户列表*/
+                    boolean found = false;    /*初始化标志位，用于标记账户是否已被找到*/
+                    for (Account accountOld : mOriAccounts) {   /*遍历原始账户列表*/
+                        if (TextUtils.equals(accountOld.name, accountNew.name)) {  /*比较账户名字是否相同*/
+                            found = true;/*如果相同，设置标志位为真*/
+                            break;  /*跳出循环*/
+                        }
+                    }
+                    if (!found) {   /*如果新账户未在原始账户列表中找到*/
+                        setSyncAccount(accountNew.name);   /*设置新账户为同步账户*/
+                        break;   /*跳出循环*/
+                    }
+                }
+            }
+        }
+
+        refreshUI();      /*刷新界面，显示最新的账户信息*/
+    }
+      
+    @Override
+    protected void onDestroy() {   /*重写 onDestroy 方法，当 Activity 被销毁时调用*/
+        if (mReceiver != null) {   /*检查 mReceiver 是否不为空*/
+            unregisterReceiver(mReceiver);  /*注销广播接收者 mReceiver，防止内存泄漏*/
+        }
+        super.onDestroy();      /*调用父类的 onDestroy 方法，完成销毁操作*/
+    }
+
+    private void loadAccountPreference() {      /*定义一个私有方法 loadAccountPreference，用于加载账户偏好设置*/
+        mAccountCategory.removeAll();    /*清空 mAccountCategory 中的所有子项*/
+
+        Preference accountPref = new Preference(this);   /*创建一个新的 Preference 对象*/
+        final String defaultAccount = getSyncAccountName(this);   /*获取当前设置的同步账户名字*/
+        accountPref.setTitle(getString(R.string.preferences_account_title));   /*设置 Preference 的标题*/
+        accountPref.setSummary(getString(R.string.preferences_account_summary));  /*设置 Preference 的摘要*/
+        accountPref.setOnPreferenceClickListener(new OnPreferenceClickListener() {
+            public boolean onPreferenceClick(Preference preference) {   /*为 Preference 设置点击监听器*/
+                if (!GTaskSyncService.isSyncing()) {   /*检查同步服务是否正在同步*/
+                    if (TextUtils.isEmpty(defaultAccount)) {    /*检查是否已经设置了同步账户*/
+                        // the first time to set account
+                        showSelectAccountAlertDialog();    /*如果没有设置同步账户，显示选择账户的对话框*/
+                    } else {
+                        // if the account has already been set, we need to promp
+                        // user about the risk
+                        showChangeAccountConfirmAlertDialog();    /*如果已经设置了同步账户，显示确认更改账户的对话框*/
+                    }
+                } else {
+                    Toast.makeText(NotesPreferenceActivity.this,
+                            R.string.preferences_toast_cannot_change_account, Toast.LENGTH_SHORT)
+                            .show();     /*如果同步服务正在同步，显示一个提示，告知用户不能更改账户*/
+                }
+                return true;   /*返回 true 表示点击事件已处理*/
+            }
+        });
+
+        mAccountCategory.addPreference(accountPref);   /*将 Preference 添加到 mAccountCategory 中*/
+    }
+
+    private void loadSyncButton() {   /*定义一个私有方法 loadSyncButton，用于加载同步按钮和最后同步时间的显示*/
+        Button syncButton = (Button) findViewById(R.id.preference_sync_button);  /*通过 ID 获取同步按钮*/
+        TextView lastSyncTimeView = (TextView) findViewById(R.id.prefenerece_sync_status_textview);   /*通过 ID 获取显示最后同步时间的 TextView*/
+
+        // set button state
+        if (GTaskSyncService.isSyncing()) {    /*检查同步服务是否正在同步*/
+            syncButton.setText(getString(R.string.preferences_button_sync_cancel));   /*如果正在同步，设置按钮文本为“取消同步”*/
+            syncButton.setOnClickListener(new View.OnClickListener() {   /*为按钮设置点击监听器*/
+                public void onClick(View v) {
+                    GTaskSyncService.cancelSync(NotesPreferenceActivity.this);    /*如果点击按钮，调用同步服务的取消同步方法*/
+                }
+            });
+        } else {
+            syncButton.setText(getString(R.string.preferences_button_sync_immediately));   /*如果不在同步，设置按钮文本为“立即同步”*/
+            syncButton.setOnClickListener(new View.OnClickListener() {
+                public void onClick(View v) {
+                    GTaskSyncService.startSync(NotesPreferenceActivity.this);   /*如果点击按钮，调用同步服务的开始同步方法*/
+                }
+            });
+        }
+        syncButton.setEnabled(!TextUtils.isEmpty(getSyncAccountName(this)));   /*设置按钮是否启用，取决于是否设置了同步账户*/
+
+        // set last sync time
+        if (GTaskSyncService.isSyncing()) {   /*检查同步服务是否正在同步*/
+            lastSyncTimeView.setText(GTaskSyncService.getProgressString());   /*如果正在同步，显示同步进度*/
+            lastSyncTimeView.setVisibility(View.VISIBLE);   /*显示 TextView*/
+        } else {
+            long lastSyncTime = getLastSyncTime(this);    /*获取最后同步的时间*/
+            if (lastSyncTime != 0) {    /*检查最后同步时间是否为零*/
+                lastSyncTimeView.setText(getString(R.string.preferences_last_sync_time,
+                        DateFormat.format(getString(R.string.preferences_last_sync_time_format),
+                                lastSyncTime)));     /*设置 TextView 显示最后同步时间*/
+                lastSyncTimeView.setVisibility(View.VISIBLE);    /*显示 TextView*/
+            } else {
+                lastSyncTimeView.setVisibility(View.GONE);    /*如果没有同步时间，隐藏 TextView*/
+            }
+        }
+    }
+
+    private void refreshUI() {    /*定义一个私有方法 refreshUI，用于刷新界面*/
+        loadAccountPreference();   /*/*调用 loadAccountPreference 方法，加载账户偏好设置*/*/
+        loadSyncButton();   /*调用 loadSyncButton 方法，加载同步按钮和最后同步时间的显示*/
+    }     
+
+    private void showSelectAccountAlertDialog() {   /*定义一个私有方法 showSelectAccountAlertDialog，用于显示选择账户的对话框*/
+        AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);   /*创建一个 AlertDialog.Builder 对象*/
+
+        View titleView = LayoutInflater.from(this).inflate(R.layout.account_dialog_title, null);   /*通过 LayoutInflater 加载自定义的对话框标题视图*/
+        TextView titleTextView = (TextView) titleView.findViewById(R.id.account_dialog_title);   /*获取标题视图中的 TextView*/
+        titleTextView.setText(getString(R.string.preferences_dialog_select_account_title));   /*设置标题文本*/
+        TextView subtitleTextView = (TextView) titleView.findViewById(R.id.account_dialog_subtitle);   /*获取副标题视图中的 TextView*?*/
+        subtitleTextView.setText(getString(R.string.preferences_dialog_select_account_tips));   /*设置副标题文本*/
+
+        dialogBuilder.setCustomTitle(titleView);    /*设置自定义的对话框标题*/
+        dialogBuilder.setPositiveButton(null, null);    /*设置正按钮（这里没有实际内容）*/
+
+        Account[] accounts = getGoogleAccounts();    /*获取设备上的所有 Google 账户*/
+        String defAccount = getSyncAccountName(this);    /*获取当前设置的同步账户名字*/
+
+        mOriAccounts = accounts;    /*记录原始账户列表*/
+        mHasAddedAccount = false;      /*标记是否已经添加过账户*/
+
+        if (accounts.length > 0) {     /*检查是否有可用的账户*/
+            CharSequence[] items = new CharSequence[accounts.length];    /*创建一个 CharSequence 数组，用于存储账户名称*/
+            final CharSequence[] itemMapping = items;    /*创建一个最终的 CharSequence 数组，用于映射选择的账户*/
+            int checkedItem = -1;   /*初始化选中的项索引*/
+            int index = 0;    /*初始化索引*/
+            for (Account account : accounts) {    /*遍历账户列表*/
+                if (TextUtils.equals(account.name, defAccount)) {   /*检查当前账户是否为默认账户*/
+                    checkedItem = index;
+                }
+                items[index++] = account.name;   /*将账户名称添加到 items 数组中*/
+            }
+            dialogBuilder.setSingleChoiceItems(items, checkedItem,
+                    new DialogInterface.OnClickListener() {
+                        public void onClick(DialogInterface dialog, int which) {   /*设置单选列表项及其点击监听器*/
+                            setSyncAccount(itemMapping[which].toString());   /*设置选中的账户为同步账户*/
+                            dialog.dismiss();   /*关闭对话框*/
+                            refreshUI();    /*刷新界面*/
+                        }
+                    });
+        }
+
+        View addAccountView = LayoutInflater.from(this).inflate(R.layout.add_account_text, null);    /*加载添加账户的视图*/
+        dialogBuilder.setView(addAccountView);    /*设置对话框的自定义视图*/
+
+        final AlertDialog dialog = dialogBuilder.show();     /*显示对话框*/
+        addAccountView.setOnClickListener(new View.OnClickListener() {   /*为添加账户视图设置点击监听器*/
+            public void onClick(View v) {
+                mHasAddedAccount = true;    /*标记已经添加过账户*/
+                Intent intent = new Intent("android.settings.ADD_ACCOUNT_SETTINGS");   /*创建一个意图，打开添加账户的设置页面*/
+                intent.putExtra(AUTHORITIES_FILTER_KEY, new String[] {
+                    "gmail-ls"    /*设置意图的额外参数，过滤账户类型*/
+                });
+                startActivityForResult(intent, -1);     /*启动活动并等待结果*/
+                dialog.dismiss();    /*关闭对话框*/
+            }
+        });
+    }
+
+    private void showChangeAccountConfirmAlertDialog() {    /*定义一个私有方法 showChangeAccountConfirmAlertDialog，用于显示确认更改账户的对话框*/
+        AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(this);   /*创建一个 AlertDialog.Builder 对象*/
+
+        View titleView = LayoutInflater.from(this).inflate(R.layout.account_dialog_title, null);   /*通过 LayoutInflater 加载自定义的对话框标题视图*/
+        TextView titleTextView = (TextView) titleView.findViewById(R.id.account_dialog_title);  /*获取标题视图中的 TextView*/
+        titleTextView.setText(getString(R.string.preferences_dialog_change_account_title,
+                getSyncAccountName(this)));     /*设置标题文本，包含当前同步账户的名字*/
+        TextView subtitleTextView = (TextView) titleView.findViewById(R.id.account_dialog_subtitle);    /*获取副标题视图中的 TextView*/
+        subtitleTextView.setText(getString(R.string.preferences_dialog_change_account_warn_msg));    /*设置副标题文本，警告用户更改账户的风险*/
+        dialogBuilder.setCustomTitle(titleView);    /*设置自定义的对话框标题*/
+
+        CharSequence[] menuItemArray = new CharSequence[] {   /*创建一个 CharSequence 数组，包含菜单项*/
+                getString(R.string.preferences_menu_change_account),
+                getString(R.string.preferences_menu_remove_account),
+                getString(R.string.preferences_menu_cancel)
+        };
+        dialogBuilder.setItems(menuItemArray, new DialogInterface.OnClickListener() {  /*设置菜单项及其点击监听器*/
+            public void onClick(DialogInterface dialog, int which) {
+                if (which == 0) {    /*如果选择了“更改账户”，显示选择账户的对话框*/
+                    showSelectAccountAlertDialog();
+                } else if (which == 1) {   /*如果选择了“移除账户”，移除同步账户并刷新界面*/
+                    removeSyncAccount();
+                    refreshUI();
+                }
+            }
+        });
+        dialogBuilder.show();   /*显示对话框*/
+    }
+
+    private Account[] getGoogleAccounts() {   /*定义一个私有方法 getGoogleAccounts，用于获取设备上的所有 Google 账户*/
+        AccountManager accountManager = AccountManager.get(this);  /*获取 AccountManager 对象*/
+        return accountManager.getAccountsByType("com.google");   /*返回所有 Google 类型的账户*/
+    }
+
+    private void setSyncAccount(String account) {   /*定义一个私有方法 setSyncAccount，用于设置同步账户*/
+        if (!getSyncAccountName(this).equals(account)) {   /*检查当前设置的同步账户是否与新账户不同*/
+            SharedPreferences settings = getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);   /*获取 SharedPreferences 对象*/
+            SharedPreferences.Editor editor = settings.edit();    /*获取 SharedPreferences 编辑器*/
+            if (account != null) {    /*如果账户不为空，将其保存到偏好设置中*/
+                editor.putString(PREFERENCE_SYNC_ACCOUNT_NAME, account);   /*保存账户名字*/
+            } else {   /*如果账户为空，保存空字符串*/
+                editor.putString(PREFERENCE_SYNC_ACCOUNT_NAME, "");   /*保存空字符串*/
+            }
+            editor.commit();   /*提交编辑*/
+
+            // clean up last sync time
+            setLastSyncTime(this, 0);   /*清除最后同步时间*/
+
+            // clean up local gtask related info
+            new Thread(new Runnable() {
+                public void run() {
+                    ContentValues values = new ContentValues();
+                    values.put(NoteColumns.GTASK_ID, "");
+                    values.put(NoteColumns.SYNC_ID, 0);
+                    getContentResolver().update(Notes.CONTENT_NOTE_URI, values, null, null);
+                }
+            }).start();   /*创建并启动一个新线程，清除本地与 GTask 相关的信息*/
+
+            Toast.makeText(NotesPreferenceActivity.this,
+                    getString(R.string.preferences_toast_success_set_accout, account),
+                    Toast.LENGTH_SHORT).show();  /*显示一个提示，告知用户成功设置了账户*/
+        }
+    }
+
+    private void removeSyncAccount() {   /*定义一个私有方法 removeSyncAccount，用于移除同步账户*/
+        SharedPreferences settings = getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);  /*获取 SharedPreferences 对象*/
+        SharedPreferences.Editor editor = settings.edit();   /*获取 SharedPreferences 编辑器*/
+        if (settings.contains(PREFERENCE_SYNC_ACCOUNT_NAME)) {    /*检查是否包含同步账户名字*/
+            editor.remove(PREFERENCE_SYNC_ACCOUNT_NAME);   /*移除同步账户名字*/
+        }
+        if (settings.contains(PREFERENCE_LAST_SYNC_TIME)) {   /*检查是否包含最后同步时间*/
+            editor.remove(PREFERENCE_LAST_SYNC_TIME);    /*移除最后同步时间*/
+        }
+        editor.commit();   /*提交编辑*/
+
+        // clean up local gtask related info
+        new Thread(new Runnable() {   /*创建并启动一个新线程，清除本地与 GTask 相关的信息*/
+            public void run() {
+                ContentValues values = new ContentValues();    /*创建 ContentValues 对象*/
+                values.put(NoteColumns.GTASK_ID, "");   /*设置 GTASK_ID 为空*/
+                values.put(NoteColumns.SYNC_ID, 0);    /*设置 SYNC_ID 为 0*/
+                getContentResolver().update(Notes.CONTENT_NOTE_URI, values, null, null);   /*更新数据库中的相关记录*/
+            }
+        }).start();
+    }
+
+    public static String getSyncAccountName(Context context) {   /*定义一个静态方法 getSyncAccountName，用于获取同步账户名字*/
+        SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME,
+                Context.MODE_PRIVATE);   /*获取 SharedPreferences 对象*/
+        return settings.getString(PREFERENCE_SYNC_ACCOUNT_NAME, "");   /*返回同步账户名字，如果没有设置则返回空字符串*/
+    }
+
+    public static void setLastSyncTime(Context context, long time) {   /*定义一个静态方法 setLastSyncTime，用于设置最后同步时间*/
+        SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME,
+                Context.MODE_PRIVATE);   /*获取 SharedPreferences 对象*/
+        SharedPreferences.Editor editor = settings.edit();   /*获取 SharedPreferences 编辑器*/
+        editor.putLong(PREFERENCE_LAST_SYNC_TIME, time);   /*保存最后同步时间*/
+        editor.commit();   /*提交编辑*/
+    }
+
+    public static long getLastSyncTime(Context context) {   /*定义一个静态方法 getLastSyncTime，用于获取最后同步时间*/
+        SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME,
+                Context.MODE_PRIVATE);    /*获取 SharedPreferences 对象*/
+        return settings.getLong(PREFERENCE_LAST_SYNC_TIME, 0);     /*返回最后同步时间，如果没有设置则返回 0*/
+    }
+
+    private class GTaskReceiver extends BroadcastReceiver {   /*定义一个内部类 GTaskReceiver，继承自 BroadcastReceiver*/
+
+        @Override
+        public void onReceive(Context context, Intent intent) {   /*重写 onReceive 方法，当接收到广播时调用*/
+            refreshUI();   /*刷新界面*/
+            if (intent.getBooleanExtra(GTaskSyncService.GTASK_SERVICE_BROADCAST_IS_SYNCING, false)) {   /*检查广播是否表示正在同步*/
+                TextView syncStatus = (TextView) findViewById(R.id.prefenerece_sync_status_textview);   /*获取显示同步状态的 TextView*/
+                syncStatus.setText(intent
+                        .getStringExtra(GTaskSyncService.GTASK_SERVICE_BROADCAST_PROGRESS_MSG));   /*设置 TextView 显示同步进度*/
+            }
+
+        }
+    }
+
+    public boolean onOptionsItemSelected(MenuItem item) {   /*重写 onOptionsItemSelected 方法，处理选项菜单项的点击事件*/
+        switch (item.getItemId()) {   /*根据菜单项的 ID 进行处理*/
+            case android.R.id.home:   /*处理 Home 按钮的点击事件*/
+                Intent intent = new Intent(this, NotesListActivity.class);    /*创建一个意图，跳转到 NotesListActivity*/
+                intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);   /*添加标志，确保活动栈中的其他活动被清除*/
+                startActivity(intent);   /*启动活动*/
+                return true;   /*返回 true 表示事件已处理*/
+            default:   /*默认情况下返回 false*/
+                return false;
+        }
+    }
+}