test123/NotesListActivity.java

/*
 * 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*/