代码注释

AlarmAlertActivity.java

@@ -0,0 +1,159 @@
+/*
+ * 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.app.Activity;
+import android.app.AlertDialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.DialogInterface.OnClickListener;
+import android.content.DialogInterface.OnDismissListener;
+import android.content.Intent;
+import android.media.AudioManager;
+import android.media.MediaPlayer;
+import android.media.RingtoneManager;
+import android.net.Uri;
+import android.os.Bundle;
+import android.os.PowerManager;
+import android.provider.Settings;
+import android.view.Window;
+import android.view.WindowManager;
+
+import net.micode.notes.R;
+import net.micode.notes.data.Notes;
+import net.micode.notes.tool.DataUtils;
+
+import java.io.IOException;
+
+// AlarmAlertActivity 是一个用于显示便签提醒的 Activity。
+public class AlarmAlertActivity extends Activity implements OnClickListener, OnDismissListener {
+    private long mNoteId; // 便签的ID。
+    private String mSnippet; // 便签的预览文本。
+    private static final int SNIPPET_PREW_MAX_LEN = 60; // 预览文本的最大长度。
+    MediaPlayer mPlayer; // 用于播放提醒声音的 MediaPlayer。
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        requestWindowFeature(Window.FEATURE_NO_TITLE); // 请求无标题栏的窗口特性。
+
+        final Window win = getWindow();
+        win.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED); // 锁屏时显示窗口。
+
+        if (!isScreenOn()) {
+            win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
+                    | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
+                    | WindowManager.LayoutParams.FLAG_ALLOW_LOCK_WHILE_SCREEN_ON
+                    | WindowManager.LayoutParams.FLAG_LAYOUT_INSET_DECOR); // 屏幕关闭时点亮屏幕。
+        }
+
+        Intent intent = getIntent(); // 获取启动该 Activity 的 Intent。
+
+        try {
+            mNoteId = Long.valueOf(intent.getData().getPathSegments().get(1)); // 从 Intent 中获取便签 ID。
+            mSnippet = DataUtils.getSnippetById(this.getContentResolver(), mNoteId); // 获取便签预览文本。
+            mSnippet = mSnippet.length() > SNIPPET_PREW_MAX_LEN ? mSnippet.substring(0,
+                    SNIPPET_PREW_MAX_LEN) + getResources().getString(R.string.notelist_string_info)
+                    : mSnippet; // 预览文本超出最大长度时截断。
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+            return;
+        }
+
+        mPlayer = new MediaPlayer(); // 初始化 MediaPlayer。
+        if (DataUtils.visibleInNoteDatabase(getContentResolver(), mNoteId, Notes.TYPE_NOTE)) {
+            showActionDialog(); // 显示操作对话框。
+            playAlarmSound(); // 播放提醒声音。
+        } else {
+            finish(); // 如果便签不可见，则结束 Activity。
+        }
+    }
+
+    // 检查屏幕是否开启。
+    private boolean isScreenOn() {
+        PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
+        return pm.isScreenOn();
+    }
+
+    // 播放提醒声音。
+    private void playAlarmSound() {
+        Uri url = RingtoneManager.getActualDefaultRingtoneUri(this, RingtoneManager.TYPE_ALARM);
+        int silentModeStreams = Settings.System.getInt(getContentResolver(),
+                Settings.System.MODE_RINGER_STREAMS_AFFECTED, 0);
+
+        if ((silentModeStreams & (1 << AudioManager.STREAM_ALARM)) != 0) {
+            mPlayer.setAudioStreamType(silentModeStreams);
+        } else {
+            mPlayer.setAudioStreamType(AudioManager.STREAM_ALARM);
+        }
+        try {
+            mPlayer.setDataSource(this, url);
+            mPlayer.prepare();
+            mPlayer.setLooping(true);
+            mPlayer.start();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalStateException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    // 显示操作对话框。
+    private void showActionDialog() {
+        AlertDialog.Builder dialog = new AlertDialog.Builder(this);
+        dialog.setTitle(R.string.app_name);
+        dialog.setMessage(mSnippet);
+        dialog.setPositiveButton(R.string.notealert_ok, this);
+        if (isScreenOn()) {
+            dialog.setNegativeButton(R.string.notealert_enter, this);
+        }
+        dialog.show().setOnDismissListener(this);
+    }
+
+    // DialogInterface.OnClickListener 的实现，处理对话框按钮点击事件。
+    public void onClick(DialogInterface dialog, int which) {
+        switch (which) {
+            case DialogInterface.BUTTON_NEGATIVE:
+                Intent intent = new Intent(this, NoteEditActivity.class);
+                intent.setAction(Intent.ACTION_VIEW);
+                intent.putExtra(Intent.EXTRA_UID, mNoteId);
+                startActivity(intent);
+                break;
+            default:
+                break;
+        }
+    }
+
+    // DialogInterface.OnDismissListener 的实现，处理对话框消失事件。
+    public void onDismiss(DialogInterface dialog) {
+        stopAlarmSound();
+        finish();
+    }
+
+    // 停止提醒声音。
+    private void stopAlarmSound() {
+        if (mPlayer != null) {
+            mPlayer.stop();
+            mPlayer.release();
+            mPlayer = null;
+        }
+    }
+}

AlarmInitReceiver.java

@@ -0,0 +1,75 @@
+/*
+ * 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;  // 指定该类所在的包路径
+
+import android.app.AlarmManager;  // 引入AlarmManager类，用于设置闹钟
+import android.app.PendingIntent;  // 引入PendingIntent类，表示延迟的Intent
+import android.content.BroadcastReceiver;  // 引入BroadcastReceiver类，用于接收广播
+import android.content.ContentUris;  // 引入ContentUris类，用于生成URI
+import android.content.Context;  // 引入Context类，用于访问系统资源
+import android.content.Intent;  // 引入Intent类，用于启动组件
+import android.database.Cursor;  // 引入Cursor类，用于数据库查询
+
+import net.micode.notes.data.Notes;  // 引入Notes类，处理笔记数据
+import net.micode.notes.data.Notes.NoteColumns;  // 引入NoteColumns类，表示Notes表的列
+
+public class AlarmInitReceiver extends BroadcastReceiver {  // 定义一个继承自BroadcastReceiver的类
+
+    // 定义查询需要的列
+    private static final String [] PROJECTION = new String [] {
+        NoteColumns.ID,  // 获取笔记的ID列
+        NoteColumns.ALERTED_DATE  // 获取提醒时间列
+    };
+
+    // 列索引常量
+    private static final int COLUMN_ID = 0;  // 第0列是ID列
+    private static final int COLUMN_ALERTED_DATE = 1;  // 第1列是提醒时间列
+
+    @Override
+    public void onReceive(Context context, Intent intent) {  // 重写onReceive方法，接收广播
+        long currentDate = System.currentTimeMillis();  // 获取当前的系统时间（以毫秒为单位）
+        
+        // 查询数据库，获取需要提醒的笔记，且提醒时间大于当前时间
+        Cursor c = context.getContentResolver().query(Notes.CONTENT_NOTE_URI,  // 查询URI为Notes.CONTENT_NOTE_URI的内容提供者
+                PROJECTION,  // 需要查询的列
+                NoteColumns.ALERTED_DATE + ">? AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE,  // 查询条件：提醒时间大于当前时间，且类型为笔记
+                new String[] { String.valueOf(currentDate) },  // 查询条件中的当前时间
+                null);  // 不需要排序
+
+        // 如果查询结果不为空
+        if (c != null) {
+            // 如果查询到至少一条记录
+            if (c.moveToFirst()) {
+                do {
+                    long alertDate = c.getLong(COLUMN_ALERTED_DATE);  // 获取提醒时间
+                    Intent sender = new Intent(context, AlarmReceiver.class);  // 创建一个新的Intent，用于发送广播
+                    sender.setData(ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, c.getLong(COLUMN_ID)));  // 设置Intent的数据（笔记的ID）
+                    
+                    // 创建PendingIntent，表示在指定时间执行AlarmReceiver广播
+                    PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, sender, 0);
+                    
+                    // 获取系统的AlarmManager服务
+                    AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
+                    
+                    // 设置闹钟，使用RTC_WAKEUP模式，当到达指定的提醒时间时唤醒设备并触发PendingIntent
+                    alarmManager.set(AlarmManager.RTC_WAKEUP, alertDate, pendingIntent);
+                } while (c.moveToNext());  // 如果查询结果中还有下一条记录，则继续处理
+            }
+            c.close();  // 关闭Cursor
+        }
+    }
+}

AlarmReceiver.java

@@ -0,0 +1,35 @@
+/*
+ * 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.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+
+// AlarmReceiver 类继承自 BroadcastReceiver，用于接收便签提醒的广播事件。
+public class AlarmReceiver extends BroadcastReceiver {
+    // onReceive 方法是 BroadcastReceiver 的回调方法，当接收到广播时被调用。
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        // 设置 intent 的目标类为 AlarmAlertActivity。
+        intent.setClass(context, AlarmAlertActivity.class);
+        // 为 intent 添加 FLAG_ACTIVITY_NEW_TASK 标志，使得在新的任务栈中启动 Activity。
+        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+        // 在给定的上下文中启动 AlarmAlertActivity。
+        context.startActivity(intent);
+    }
+}

DateTimePicker.java

@@ -0,0 +1,222 @@
+/*
+ * 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 java.text.DateFormatSymbols;
+import java.util.Calendar;
+
+import net.micode.notes.R;
+
+
+import android.content.Context;
+import android.text.format.DateFormat;
+import android.view.View;
+import android.widget.FrameLayout;
+import android.widget.NumberPicker;
+
+// DateTimePicker 类继承自 FrameLayout，用于提供一个日期时间选择器。
+public class DateTimePicker extends FrameLayout {
+
+    // 默认启用状态。
+    private static final boolean DEFAULT_ENABLE_STATE = true;
+
+    // 半天的小时数和全天的小时数。
+    private static final int HOURS_IN_HALF_DAY = 12;
+    private static final int HOURS_IN_ALL_DAY = 24;
+    // 一周的天数。
+    private static final int DAYS_IN_ALL_WEEK = 7;
+    // 日期选择器的最小值和最大值。
+    private static final int DATE_SPINNER_MIN_VAL = 0;
+    private static final int DATE_SPINNER_MAX_VAL = DAYS_IN_ALL_WEEK - 1;
+    // 24小时制和12小时制下小时选择器的最小值和最大值。
+    private static final int HOUR_SPINNER_MIN_VAL_24_HOUR_VIEW = 0;
+    private static final int HOUR_SPINNER_MAX_VAL_24_HOUR_VIEW = 23;
+    private static final int HOUR_SPINNER_MIN_VAL_12_HOUR_VIEW = 1;
+    private static final int HOUR_SPINNER_MAX_VAL_12_HOUR_VIEW = 12;
+    // 分钟选择器的最小值和最大值。
+    private static final int MINUT_SPINNER_MIN_VAL = 0;
+    private static final int MINUT_SPINNER_MAX_VAL = 59;
+    // 上下午选择器的最小值和最大值。
+    private static final int AMPM_SPINNER_MIN_VAL = 0;
+    private static final int AMPM_SPINNER_MAX_VAL = 1;
+
+    // 日期、小时、分钟和上下午的 NumberPicker 控件。
+    private final NumberPicker mDateSpinner;
+    private final NumberPicker mHourSpinner;
+    private final NumberPicker mMinuteSpinner;
+    private final NumberPicker mAmPmSpinner;
+    // 用于存储日期的 Calendar 对象。
+    private Calendar mDate;
+
+    // 日期显示值数组。
+    private String[] mDateDisplayValues = new String[DAYS_IN_ALL_WEEK];
+
+    // 表示是否为上午的布尔值。
+    private boolean mIsAm;
+
+    // 表示是否为24小时视图的布尔值。
+    private boolean mIs24HourView;
+
+    // 控件的启用状态。
+    private boolean mIsEnabled = DEFAULT_ENABLE_STATE;
+
+    // 正在初始化的布尔值。
+    private boolean mInitialising;
+
+    // 日期时间改变监听器。
+    private OnDateTimeChangedListener mOnDateTimeChangedListener;
+
+    // 日期改变监听器。
+    private NumberPicker.OnValueChangeListener mOnDateChangedListener = new NumberPicker.OnValueChangeListener() {
+        @Override
+        public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
+            // 更新日期并通知日期时间改变。
+            mDate.add(Calendar.DAY_OF_YEAR, newVal - oldVal);
+            updateDateControl();
+            onDateTimeChanged();
+        }
+    };
+
+    // 小时改变监听器。
+    private NumberPicker.OnValueChangeListener mOnHourChangedListener = new NumberPicker.OnValueChangeListener() {
+        @Override
+        public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
+            // 更新小时并通知日期时间改变。
+            // 处理12小时制下上下午的转换。
+            boolean isDateChanged = false;
+            Calendar cal = Calendar.getInstance();
+            if (!mIs24HourView) {
+                if (!mIsAm && oldVal == HOURS_IN_HALF_DAY - 1 && newVal == HOURS_IN_HALF_DAY) {
+                    cal.setTimeInMillis(mDate.getTimeInMillis());
+                    cal.add(Calendar.DAY_OF_YEAR, 1);
+                    isDateChanged = true;
+                } else if (mIsAm && oldVal == HOURS_IN_HALF_DAY && newVal == HOURS_IN_HALF_DAY - 1) {
+                    cal.setTimeInMillis(mDate.getTimeInMillis());
+                    cal.add(Calendar.DAY_OF_YEAR, -1);
+                    isDateChanged = true;
+                }
+                if (oldVal == HOURS_IN_HALF_DAY - 1 && newVal == HOURS_IN_HALF_DAY ||
+                        oldVal == HOURS_IN_HALF_DAY && newVal == HOURS_IN_HALF_DAY - 1) {
+                    mIsAm = !mIsAm;
+                    updateAmPmControl();
+                }
+            } else {
+                if (oldVal == HOURS_IN_ALL_DAY - 1 && newVal == 0) {
+                    cal.setTimeInMillis(mDate.getTimeInMillis());
+                    cal.add(Calendar.DAY_OF_YEAR, 1);
+                    isDateChanged = true;
+                } else if (oldVal == 0 && newVal == HOURS_IN_ALL_DAY - 1) {
+                    cal.setTimeInMillis(mDate.getTimeInMillis());
+                    cal.add(Calendar.DAY_OF_YEAR, -1);
+                    isDateChanged = true;
+                }
+            }
+            int newHour = mHourSpinner.getValue() % HOURS_IN_HALF_DAY + (mIsAm ? 0 : HOURS_IN_HALF_DAY);
+            mDate.set(Calendar.HOUR_OF_DAY, newHour);
+            onDateTimeChanged();
+            if (isDateChanged) {
+                setCurrentYear(cal.get(Calendar.YEAR));
+                setCurrentMonth(cal.get(Calendar.MONTH));
+                setCurrentDay(cal.get(Calendar.DAY_OF_MONTH));
+            }
+        }
+    };
+
+    // 分钟改变监听器。
+    private NumberPicker.OnValueChangeListener mOnMinuteChangedListener = new NumberPicker.OnValueChangeListener() {
+        @Override
+        public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
+            // 更新分钟并通知日期时间改变。
+            int minValue = mMinuteSpinner.getMinValue();
+            int maxValue = mMinuteSpinner.getMaxValue();
+            int offset = 0;
+            if (oldVal == maxValue && newVal == minValue) {
+                offset += 1;
+            } else if (oldVal == minValue && newVal == maxValue) {
+                offset -= 1;
+            }
+            if (offset != 0) {
+                mDate.add(Calendar.HOUR_OF_DAY, offset);
+                mHourSpinner.setValue(getCurrentHour());
+                updateDateControl();
+                int newHour = getCurrentHourOfDay();
+                if (newHour >= HOURS_IN_HALF_DAY) {
+                    mIsAm = false;
+                    updateAmPmControl();
+                } else {
+                    mIsAm = true;
+                    updateAmPmControl();
+                }
+            }
+            mDate.set(Calendar.MINUTE, newVal);
+            onDateTimeChanged();
+        }
+    };
+
+    // 上下午改变监听器。
+    private NumberPicker.OnValueChangeListener mOnAmPmChangedListener = new NumberPicker.OnValueChangeListener() {
+        @Override
+        public void onValueChange(NumberPicker picker, int oldVal, int newVal) {
+            // 更新上下午并通知日期时间改变。
+            mIsAm = !mIsAm;
+            if (mIsAm) {
+                mDate.add(Calendar.HOUR_OF_DAY, -HOURS_IN_HALF_DAY);
+            } else {
+                mDate.add(Calendar.HOUR_OF_DAY, HOURS_IN_HALF_DAY);
+            }
+            updateAmPmControl();
+            onDateTimeChanged();
+        }
+    };
+
+    // 日期时间改变监听器接口。
+    public interface OnDateTimeChangedListener {
+        void onDateTimeChanged(DateTimePicker view, int year, int month,
+                int dayOfMonth, int hourOfDay, int minute);
+    }
+
+    // DateTimePicker 的构造函数。
+    public DateTimePicker(Context context) {
+        this(context, System.currentTimeMillis());
+    }
+
+    public DateTimePicker(Context context, long date) {
+        this(context, date, DateFormat.is24HourFormat(context));
+    }
+
+    public DateTimePicker(Context context, long date, boolean is24HourView) {
+        super(context);
+        mDate = Calendar.getInstance();
+        mInitialising = true;
+        mIsAm = getCurrentHourOfDay() >= HOURS_IN_HALF_DAY;
+        inflate(context, R.layout.datetime_picker, this);
+
+        // 初始化日期、小时、分钟和上下午的 NumberPicker 控件。
+        mDateSpinner = (NumberPicker) findViewById(R.id.date);
+        mDateSpinner.setMinValue(DATE_SPINNER_MIN_VAL);
+        mDateSpinner.setMaxValue(DATE_SPINNER_MAX_VAL);
+        mDateSpinner.setOnValueChangedListener(mOnDateChangedListener);
+
+        mHourSpinner = (NumberPicker) findViewById(R.id.hour);
+        mHourSpinner.setOnValueChangedListener(mOnHourChangedListener);
+        mMinuteSpinner =  (NumberPicker) findViewById(R.id.minute);
+        mMinuteSpinner.setMinValue(MINUT_SPINNER_MIN_VAL);
+        mMinuteSpinner.setMaxValue(MINUT_SPINNER_MAX_VAL);
+        mMinuteSpinner.setOnLongPressUpdateInterval(100);
+        mMinuteSpinner.setOnValueChangedListener(mOnMinuteChangedListener);
+
+        //

DateTimePickerDialog.java

@@ -0,0 +1,98 @@
+/*
+ * 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;  // 定义类所在的包路径
+
+import java.util.Calendar;  // 引入Calendar类用于处理日期和时间
+
+import net.micode.notes.R;  // 引入R文件，用于获取资源ID
+import net.micode.notes.ui.DateTimePicker;  // 引入自定义的DateTimePicker控件
+import net.micode.notes.ui.DateTimePicker.OnDateTimeChangedListener;  // 引入DateTimePicker控件的监听器
+
+import android.app.AlertDialog;  // 引入AlertDialog类，用于创建对话框
+import android.content.Context;  // 引入Context类，用于访问应用程序上下文
+import android.content.DialogInterface;  // 引入DialogInterface类，用于处理对话框的按钮事件
+import android.content.DialogInterface.OnClickListener;  // 引入OnClickListener接口，用于按钮点击事件
+import android.text.format.DateFormat;  // 引入DateFormat类，用于格式化日期和时间
+import android.text.format.DateUtils;  // 引入DateUtils类，用于时间格式化与操作
+
+// 定义一个自定义的DateTimePickerDialog类，继承自AlertDialog
+public class DateTimePickerDialog extends AlertDialog implements OnClickListener {
+
+    private Calendar mDate = Calendar.getInstance();  // 用于保存当前日期和时间
+    private boolean mIs24HourView;  // 标记是否为24小时制显示
+    private OnDateTimeSetListener mOnDateTimeSetListener;  // 回调接口，用于在日期和时间设置后通知调用者
+    private DateTimePicker mDateTimePicker;  // 自定义的日期时间选择器
+
+    // 定义回调接口，用于在用户设置日期时间后进行处理
+    public interface OnDateTimeSetListener {
+        void OnDateTimeSet(AlertDialog dialog, long date);  // 回调方法，传递设置的日期时间
+    }
+
+    // 构造函数，初始化对话框，设置默认日期时间
+    public DateTimePickerDialog(Context context, long date) {
+        super(context);  // 调用父类构造函数，初始化AlertDialog
+        mDateTimePicker = new DateTimePicker(context);  // 初始化DateTimePicker控件
+        setView(mDateTimePicker);  // 设置对话框的内容视图为DateTimePicker控件
+        mDateTimePicker.setOnDateTimeChangedListener(new OnDateTimeChangedListener() {  // 设置日期时间变化的监听器
+            public void onDateTimeChanged(DateTimePicker view, int year, int month,
+                    int dayOfMonth, int hourOfDay, int minute) {
+                mDate.set(Calendar.YEAR, year);  // 设置选中的年
+                mDate.set(Calendar.MONTH, month);  // 设置选中的月
+                mDate.set(Calendar.DAY_OF_MONTH, dayOfMonth);  // 设置选中的天
+                mDate.set(Calendar.HOUR_OF_DAY, hourOfDay);  // 设置选中的小时
+                mDate.set(Calendar.MINUTE, minute);  // 设置选中的分钟
+                updateTitle(mDate.getTimeInMillis());  // 更新对话框标题显示的日期时间
+            }
+        });
+        mDate.setTimeInMillis(date);  // 将传入的日期时间（毫秒）设置为当前日期
+        mDate.set(Calendar.SECOND, 0);  // 将秒设置为0
+        mDateTimePicker.setCurrentDate(mDate.getTimeInMillis());  // 设置DateTimePicker控件的初始日期
+        setButton(context.getString(R.string.datetime_dialog_ok), this);  // 设置“确认”按钮，并指定点击时的行为
+        setButton2(context.getString(R.string.datetime_dialog_cancel), (OnClickListener)null);  // 设置“取消”按钮
+        set24HourView(DateFormat.is24HourFormat(this.getContext()));  // 设置是否为24小时制显示
+        updateTitle(mDate.getTimeInMillis());  // 初始化时更新对话框的标题
+    }
+
+    // 设置是否使用24小时制
+    public void set24HourView(boolean is24HourView) {
+        mIs24HourView = is24HourView;
+    }
+
+    // 设置日期时间设置完成后的回调监听器
+    public void setOnDateTimeSetListener(OnDateTimeSetListener callBack) {
+        mOnDateTimeSetListener = callBack;
+    }
+
+    // 更新对话框标题，显示当前选中的日期时间
+    private void updateTitle(long date) {
+        // 设置日期时间显示的格式
+        int flag =
+            DateUtils.FORMAT_SHOW_YEAR |  // 显示年份
+            DateUtils.FORMAT_SHOW_DATE |  // 显示日期
+            DateUtils.FORMAT_SHOW_TIME;  // 显示时间
+        flag |= mIs24HourView ? DateUtils.FORMAT_24HOUR : DateUtils.FORMAT_24HOUR;  // 如果是24小时制，显示24小时格式
+        setTitle(DateUtils.formatDateTime(this.getContext(), date, flag));  // 格式化日期时间并设置为对话框标题
+    }
+
+    // 确认按钮点击事件的处理
+    public void onClick(DialogInterface arg0, int arg1) {
+        if (mOnDateTimeSetListener != null) {
+            // 调用回调接口，传递设置的日期时间
+            mOnDateTimeSetListener.OnDateTimeSet(this, mDate.getTimeInMillis());
+        }
+    }
+}

DropdownMenu.java

@@ -0,0 +1,63 @@
+/*
+ * 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;  // 定义类所在的包路径
+
+import android.content.Context;  // 引入Context类，用于访问应用程序的上下文
+import android.view.Menu;  // 引入Menu类，用于操作菜单
+import android.view.MenuItem;  // 引入MenuItem类，用于菜单项的处理
+import android.view.View;  // 引入View类，用于视图的操作
+import android.view.View.OnClickListener;  // 引入OnClickListener接口，用于处理点击事件
+import android.widget.Button;  // 引入Button类，用于显示按钮
+import android.widget.PopupMenu;  // 引入PopupMenu类，用于显示弹出菜单
+import android.widget.PopupMenu.OnMenuItemClickListener;  // 引入PopupMenu的菜单项点击监听器
+
+public class DropdownMenu {
+    private Button mButton;  // 用于显示的按钮，点击后弹出菜单
+    private PopupMenu mPopupMenu;  // 弹出菜单的实例
+    private Menu mMenu;  // 菜单项的集合
+
+    // 构造函数，初始化DropdownMenu，设置按钮及其弹出菜单
+    public DropdownMenu(Context context, Button button, int menuId) {
+        mButton = button;  // 获取传入的按钮对象
+        mButton.setBackgroundResource(R.drawable.dropdown_icon);  // 设置按钮的背景图标为下拉菜单图标
+        mPopupMenu = new PopupMenu(context, mButton);  // 初始化PopupMenu，指定按钮作为弹出菜单的锚点
+        mMenu = mPopupMenu.getMenu();  // 获取PopupMenu中的Menu对象
+        mPopupMenu.getMenuInflater().inflate(menuId, mMenu);  // 使用传入的menuId加载菜单资源
+        mButton.setOnClickListener(new OnClickListener() {  // 为按钮设置点击事件监听器
+            public void onClick(View v) {
+                mPopupMenu.show();  // 当按钮被点击时，显示弹出菜单
+            }
+        });
+    }
+
+    // 设置菜单项点击事件监听器
+    public void setOnDropdownMenuItemClickListener(OnMenuItemClickListener listener) {
+        if (mPopupMenu != null) {
+            mPopupMenu.setOnMenuItemClickListener(listener);  // 设置PopupMenu的菜单项点击监听器
+        }
+    }
+
+    // 根据菜单项的ID查找菜单项
+    public MenuItem findItem(int id) {
+        return mMenu.findItem(id);  // 在菜单中查找具有指定ID的菜单项
+    }
+
+    // 设置按钮的文本
+    public void setTitle(CharSequence title) {
+        mButton.setText(title);  // 设置按钮的文本为传入的title
+    }
+}

FoldersListAdapter.java

@@ -1,89 +0,0 @@
-/*
- * 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.database.Cursor;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.CursorAdapter;
-import android.widget.LinearLayout;
-import android.widget.TextView;
-
-import net.micode.notes.R;
-import net.micode.notes.data.Notes;
-import net.micode.notes.data.Notes.NoteColumns;
-
-
-// FoldersListAdapter 是一个自定义的 CursorAdapter，用于显示文件夹列表。
-public class FoldersListAdapter extends CursorAdapter {
-    // 定义查询数据库时需要的列。
-    public static final String [] PROJECTION = {
-        NoteColumns.ID,
-        NoteColumns.SNIPPET
-    };
-
-    // 定义列索引常量。
-    public static final int ID_COLUMN   = 0;
-    public static final int NAME_COLUMN = 1;
-
-    // FoldersListAdapter 的构造函数。
-    public FoldersListAdapter(Context context, Cursor c) {
-        super(context, c);
-        // TODO Auto-generated constructor stub
-    }
-
-    // 新建视图的方法，返回一个 FolderListItem 实例。
-    @Override
-    public View newView(Context context, Cursor cursor, ViewGroup parent) {
-        return new FolderListItem(context);
-    }
-
-    // 绑定视图与数据的方法。
-    @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);
-        }
-    }
-
-    // 根据位置获取文件夹名称的方法。
-    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);
-    }
-
-    // FolderListItem 是一个内部类，表示列表中的单个文件夹项。
-    private class FolderListItem extends LinearLayout {
-        private TextView mName; // 用于显示文件夹名称的 TextView。
-
-        // FolderListItem 的构造函数。
-        public FolderListItem(Context context) {
-            super(context);
-            inflate(context, R.layout.folder_list_item, this);
-            mName = (TextView) findViewById(R.id.tv_folder_name);
-        }
-
-        // 绑定文件夹名称的方法。
-        public void bind(String name) {
-            mName.setText(name);
-        }
-    }
-}

NoteWidgetProvider.java

@@ -0,0 +1,144 @@
+/*
+ * 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;
+
+// 继承自AppWidgetProvider的抽象类，用于管理便签小部件。
+public abstract class NoteWidgetProvider extends AppWidgetProvider {
+    // 定义查询数据库时需要的列。
+    public static final String [] PROJECTION = new String [] {
+        NoteColumns.ID,
+        NoteColumns.BG_COLOR_ID,
+        NoteColumns.SNIPPET
+    };
+
+    // 定义列索引常量。
+    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，用于Logcat中识别日志来源。
+    private static final String TAG = "NoteWidgetProvider";
+
+    // 当小部件被删除时调用，更新数据库中对应的笔记widget id为无效值。
+    @Override
+    public void onDeleted(Context context, int[] appWidgetIds) {
+        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])});
+        }
+    }
+
+    // 获取小部件相关的笔记信息。
+    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);
+    }
+
+    // 更新小部件显示。
+    protected void update(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
+        update(context, appWidgetManager, appWidgetIds, false);
+    }
+
+    // 更新小部件显示，考虑隐私模式。
+    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) {
+                int bgId = ResourceParser.getDefaultBgId(context);
+                String snippet = "";
+                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());
+
+                Cursor c = getNoteWidgetInfo(context, appWidgetIds[i]);
+                if (c != null && c.moveToFirst()) {
+                    if (c.getCount() > 1) {
+                        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 {
+                    snippet = context.getResources().getString(R.string.widget_havenot_content);
+                    intent.setAction(Intent.ACTION_INSERT_OR_EDIT);
+                }
+
+                if (c != null) {
+                    c.close();
+                }
+
+                // 设置小部件的布局和行为。
+                RemoteViews rv = new RemoteViews(context.getPackageName(), getLayoutId());
+                rv.setImageViewResource(R.id.widget_bg_image, getBgResourceId(bgId));
+                intent.putExtra(Notes.INTENT_EXTRA_BACKGROUND_ID, bgId);
+                /**
+                 * 生成启动宿主的PendingIntent。
+                 */
+                PendingIntent pendingIntent = null;
+                if (privacyMode) {
+                    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 {
+                    rv.setTextViewText(R.id.widget_text, snippet);
+                    pendingIntent = PendingIntent.getActivity(context, appWidgetIds[i], intent,
+                            PendingIntent.FLAG_UPDATE_CURRENT);
+                }
+
+                rv.setOnClickPendingIntent(R.id.widget_text, pendingIntent);
+                appWidgetManager.updateAppWidget(appWidgetIds[i], rv);
+            }
+        }
+    }
+
+    // 获取背景资源ID的方法，需由子类实现。
+    protected abstract int getBgResourceId(int bgId);
+
+    // 获取布局ID的方法，需由子类实现。
+    protected abstract int getLayoutId();
+
+    // 获取小部件类型的方法，需由子类实现。
+    protected abstract int getWidgetType();
+}

NoteWidgetProvider_2x.java

@@ -0,0 +1,55 @@
+/*
+ * 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;
+
+// NoteWidgetProvider_2x 是 NoteWidgetProvider 的具体实现类，用于提供2x2网格大小的便签小部件。
+public class NoteWidgetProvider_2x extends NoteWidgetProvider {
+    // 当小部件需要更新时调用此方法。
+    @Override
+    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
+        // 调用父类的 update 方法来执行更新。
+        super.update(context, appWidgetManager, appWidgetIds);
+    }
+
+    // 返回小部件的布局资源ID。
+    @Override
+    protected int getLayoutId() {
+        // 返回2x2网格小部件的布局资源ID。
+        return R.layout.widget_2x;
+    }
+
+    // 根据传入的背景ID返回对应的资源ID。
+    @Override
+    protected int getBgResourceId(int bgId) {
+        // 使用 ResourceParser 类的静态方法来获取2x2网格小部件的背景资源ID。
+        return ResourceParser.WidgetBgResources.getWidget2xBgResource(bgId);
+    }
+
+    // 返回小部件的类型。
+    @Override
+    protected int getWidgetType() {
+        // 返回小部件的类型为TYPE_WIDGET_2X，这是一个定义在Notes类中的常量。
+        return Notes.TYPE_WIDGET_2X;
+    }
+}

NoteWidgetProvider_4x.java

@@ -0,0 +1,55 @@
+/*
+ * 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;
+
+// NoteWidgetProvider_4x 类继承自 NoteWidgetProvider 类，用于提供4x4网格大小的便签小部件。
+public class NoteWidgetProvider_4x extends NoteWidgetProvider {
+    // 当小部件需要更新时，系统会调用此方法。
+    @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);
+    }
+
+    // 返回小部件的布局资源ID。
+    @Override
+    protected int getLayoutId() {
+        // 返回4x4网格小部件的布局资源ID。
+        return R.layout.widget_4x;
+    }
+
+    // 根据传入的背景ID返回对应的资源ID。
+    @Override
+    protected int getBgResourceId(int bgId) {
+        // 使用 ResourceParser 类的静态方法来获取4x4网格小部件的背景资源ID。
+        return ResourceParser.WidgetBgResources.getWidget4xBgResource(bgId);
+    }
+
+    // 返回小部件的类型。
+    @Override
+    protected int getWidgetType() {
+        // 返回小部件的类型为TYPE_WIDGET_4X，这是一个定义在Notes类中的常量。
+        return Notes.TYPE_WIDGET_4X;
+    }
+}