read/NoteWidgetProvider.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.widget;// 包声明，指明代码属于哪个包
import android.app.PendingIntent;// 导入PendingIntent类
import android.appwidget.AppWidgetManager;// 导入AppWidgetManager类
import android.appwidget.AppWidgetProvider;// 导入AppWidgetProvider类
import android.content.ContentValues;// 导入ContentValues类
import android.content.Context;// 导入Context类
import android.content.Intent;// 导入Intent类
import android.database.Cursor;// 导入Cursor类
import android.util.Log;// 导入Log类
import android.widget.RemoteViews;// 导入RemoteViews类

import net.micode.notes.R;// 导入R类，用于访问资源
import net.micode.notes.data.Notes;// 导入Notes类
import net.micode.notes.data.Notes.NoteColumns;// 导入NoteColumns类
import net.micode.notes.tool.ResourceParser;// 导入ResourceParser类
import net.micode.notes.ui.NoteEditActivity;// 导入NoteEditActivity类
import net.micode.notes.ui.NotesListActivity;// 导入NotesListActivity类

public abstract class NoteWidgetProvider extends AppWidgetProvider {// 声明一个抽象类NoteWidgetProvider，继承自AppWidgetProvider
    public static final String [] PROJECTION = new String [] {
        NoteColumns.ID,
        NoteColumns.BG_COLOR_ID,
        NoteColumns.SNIPPET
    };// 定义一个常量数组PROJECTION，包含NoteColumns的ID、BG_COLOR_ID和SNIPPET

    public static final int COLUMN_ID           = 0;// 定义COLUMN_ID常量，值为0
    public static final int COLUMN_BG_COLOR_ID  = 1;// 定义COLUMN_BG_COLOR_ID常量，值为1
    public static final int COLUMN_SNIPPET      = 2;// 定义COLUMN_SNIPPET常量，值为2

    private static final String TAG = "NoteWidgetProvider";// 定义TAG常量，用于日志记录

    @Override
    public void onDeleted(Context context, int[] appWidgetIds) {// 重写onDeleted方法，当小部件被删除时调用
        ContentValues values = new ContentValues();// 创建ContentValues对象
        values.put(NoteColumns.WIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID);// 将WIDGET_ID列的值设置为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])});// 更新数据库，将指定小部件ID的WIDGET_ID列设置为INVALID_APPWIDGET_ID
        }
    }

    private Cursor getNoteWidgetInfo(Context context, int widgetId) {// 定义getNoteWidgetInfo方法，获取小部件信息
        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);// 查询数据库，返回符合条件的Cursor对象
    }

    protected void update(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {// 定义update方法，更新小部件
        update(context, appWidgetManager, appWidgetIds, false);
    }// 调用重载的update方法，传入false作为privacyMode参数

    private void update(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds,
            boolean privacyMode) {// 定义重载的update方法，更新小部件，传入privacyMode参数
        for (int i = 0; i < appWidgetIds.length; i++) {
            if (appWidgetIds[i] != AppWidgetManager.INVALID_APPWIDGET_ID) {// 如果小部件ID有效
                int bgId = ResourceParser.getDefaultBgId(context);// 获取默认背景ID
                String snippet = "";// 初始化snippet字符串
                Intent intent = new Intent(context, NoteEditActivity.class);// 创建Intent对象，指向NoteEditActivity
                intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);// 设置Intent标志，确保活动位于任务栈顶部
                intent.putExtra(Notes.INTENT_EXTRA_WIDGET_ID, appWidgetIds[i]);// 添加额外数据，指定小部件ID
                intent.putExtra(Notes.INTENT_EXTRA_WIDGET_TYPE, getWidgetType());// 添加额外数据，指定小部件类型

                Cursor c = getNoteWidgetInfo(context, appWidgetIds[i]);// 获取小部件信息的Cursor对象
                if (c != null && c.moveToFirst()) {// 如果Cursor不为空且移动到第一条记录
                    if (c.getCount() > 1) {// 如果记录数大于1
                        Log.e(TAG, "Multiple message with same widget id:" + appWidgetIds[i]);// 记录错误日志
                        c.close();
                        return;
                    }
                    snippet = c.getString(COLUMN_SNIPPET);// 获取SNIPPET列的值
                    bgId = c.getInt(COLUMN_BG_COLOR_ID);// 获取BG_COLOR_ID列的值
                    intent.putExtra(Intent.EXTRA_UID, c.getLong(COLUMN_ID)); // 添加额外数据，指定记录ID
                    intent.setAction(Intent.ACTION_VIEW);
                } else {
                    snippet = context.getResources().getString(R.string.widget_havenot_content);
                    intent.setAction(Intent.ACTION_INSERT_OR_EDIT);
                }// 设置Intent动作为ACTION_INSERT_OR_EDIT

                if (c != null) {
                    c.close();
                }

                RemoteViews rv = new RemoteViews(context.getPackageName(), getLayoutId());// 创建RemoteViews对象，指定布局ID
                rv.setImageViewResource(R.id.widget_bg_image, getBgResourceId(bgId));
                intent.putExtra(Notes.INTENT_EXTRA_BACKGROUND_ID, bgId);// 设置背景图片资源ID
                /**
                 * Generate the pending intent to start host for the widget
                 */
                PendingIntent pendingIntent = null;
                if (privacyMode) { // 如果隐私模式
                    rv.setTextViewText(R.id.widget_text,
                            context.getString(R.string.widget_under_visit_mode));// 设置文本视图内容为隐私模式提示
                    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);// 创建PendingIntent对象，指向NoteEditActivity
                }

                rv.setOnClickPendingIntent(R.id.widget_text, pendingIntent);// 设置文本视图的点击
                appWidgetManager.updateAppWidget(appWidgetIds[i], rv);
            }
        }
    }

    protected abstract int getBgResourceId(int bgId);// 声明抽象方法getBgResourceId，获取背景资源ID

    protected abstract int getLayoutId();// 声明抽象方法getLayoutId，获取布局ID

    protected abstract int getWidgetType();// 声明抽象方法getWidgetType
}