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Widgets基础篇附件1(WordWidget.java)  

2011-07-26 15:50:55|  分类: 开发专题 |  标签: |举报 |字号 订阅

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原文地址:http://code.google.com/p/wiktionary-android/source/browse/trunk/Wiktionary/src/com/example/android/wiktionary/WordWidget.java
因为AppWidgetProvider扩展自BroadcastReceiver, 所以,你不能保证回调函数完成调用后,AppWidgetProvider还在继续运行。
,如果你的App Widget的初始化需要多达几秒的时间(比如需要进行WEB请求),而且希望AppWidgetProvider的进程能够长久运行,那么你可以考虑在onUpdate() 中启动一个Service。
在这个Service,你可以更新你的App Widget,这样就不用担心AppWidgetProvider因为ANR错误而被迫关闭。具体参照示例1
示例1
WordWidget.java文件
/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * 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 com.example.android.wiktionary;

import com.example.android.wiktionary.SimpleWikiHelper.ApiException;
import com.example.android.wiktionary.SimpleWikiHelper.ParseException;

import android.app.PendingIntent;
import android.app.Service;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.net.Uri;
import android.os.IBinder;
import android.text.format.Time;
import android.util.Log;
import android.widget.RemoteViews;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Define a simple widget that shows the Wiktionary "Word of the day." To build
 * an update we spawn a background {@link Service} to perform the API queries.
 */
public class WordWidget extends AppWidgetProvider {
    /**
     * Regular expression that splits "Word of the day" entry into word
     * name, word type, and the first description bullet point.
     */
    public static final String WOTD_PATTERN =
        "(?s)\\{\\{wotd\\|(.+?)\\|(.+?)\\|([^#\\|]+).*?\\}\\}";

    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        Log.d("WordWidget.UpdateService", "onUpdate()");
        // To prevent any ANR timeouts, we perform the update in a service
        context.startService(new Intent(context, UpdateService.class));
    }
    
    public static class UpdateService extends Service {
        @Override
        public int onStartCommand(Intent intent, int startId) {
            Log.d("WordWidget.UpdateService", "onStart()");

            // Build the widget update for today
            RemoteViews updateViews = buildUpdate(this);
            Log.d("WordWidget.UpdateService", "update built");
            
            // Push update for this widget to the home screen
            ComponentName thisWidget = new ComponentName(this, WordWidget.class);
            AppWidgetManager manager = AppWidgetManager.getInstance(this);
            manager.updateAppWidget(thisWidget, updateViews);
            Log.d("WordWidget.UpdateService", "widget updated");
            return START_NOT_STICKY;
        }

        @Override
        public IBinder onBind(Intent intent) {
            return null;
        }
        
        /**
         * Build a widget update to show the current Wiktionary
         * "Word of the day." Will block until the online API returns.
         */
        public RemoteViews buildUpdate(Context context) {
            // Pick out month names from resources
            Resources res = context.getResources();
            String[] monthNames = res.getStringArray(R.array.month_names);
            
            // Find current month and day
            Time today = new Time();
            today.setToNow();

            // Build the page title for today, such as "March 21"
            String pageName = res.getString(R.string.template_wotd_title,
                    monthNames[today.month], today.monthDay);
            String pageContent = null;
            
            try {
                // Try querying the Wiktionary API for today's word
                SimpleWikiHelper.prepareUserAgent(context);
                pageContent = SimpleWikiHelper.getPageContent(pageName, false);
            } catch (ApiException e) {
                Log.e("WordWidget", "Couldn't contact API", e);
            } catch (ParseException e) {
                Log.e("WordWidget", "Couldn't parse API response", e);
            }
            
            RemoteViews views = null;
            Matcher matcher = null;
            
                Prefs prefs = new Prefs(this);
            if (pageContent == null) {
                // could not get content, use cache
                // could be null
                pageContent = prefs.getPageContent();
            }
            
            if (pageContent != null) {
                // we have page content
                // is it valid?
                matcher = Pattern.compile(WOTD_PATTERN).matcher(pageContent);
            }
            if (matcher != null && matcher.find()) {
                // valid content, cache it 
                // ensure that latest valid content is
                // always cached in case of failures
                prefs.setPageContent(pageContent);

                // Build an update that holds the updated widget contents
                views = new RemoteViews(context.getPackageName(), R.layout.widget_word);
                
                String wordTitle = matcher.group(1);
                views.setTextViewText(R.id.word_title, wordTitle);
                views.setTextViewText(R.id.word_type, matcher.group(2));
                views.setTextViewText(R.id.definition, matcher.group(3).trim());
                
                // When user clicks on widget, launch to Wiktionary definition page
                String definePage = String.format("%s://%s/%s", ExtendedWikiHelper.WIKI_AUTHORITY,
                        ExtendedWikiHelper.WIKI_LOOKUP_HOST, wordTitle);
                Intent defineIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(definePage));
                PendingIntent pendingIntent = PendingIntent.getActivity(context,
                        0 /* no requestCode */, defineIntent, 0 /* no flags */);
                views.setOnClickPendingIntent(R.id.widget, pendingIntent);
                
            } else {
                // Didn't find word of day, so show error message
                views = new RemoteViews(context.getPackageName(), R.layout.widget_message);
                views.setTextViewText(R.id.message, context.getString(R.string.widget_error));
            }
            return views;
        }
    }
}
注意1原文的Service用的是UpdateService,该方法应该过时,我在这里将它换为了 onStartCommand。
注意2manager.updateAppWidget(thisWidget, updateViews);这里表示的是对WordWidget的所有实例都用updateView进行更新。
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