test123/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;
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();
}