1.一个简单的widget

由于我的需求非常easy不须要写一个程序再提供一个widget。所以直接一个AppWidgetProvider就好也就不须要AppWidgetHost 。

先在AndroidManifest里面增加一个receiver

<receiver android:name="WidgetProvider">
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.appwidget.action.ACTION_APPWIDGET_ENABLED" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.appwidget.action.ACTION_APPWIDGET_DELETED" />
            </intent-filter>
            <meta-data android:name="android.appwidget.provider"
                android:resource="@xml/widget_provider"/>
        </receiver>

WidgetProvider是继承AppWidgetProvider的一个类，用来widget的详细响应实现。

里面的<meta-data android:name="android.appwidget.provider" android:resource="@xml/widget_provider"/>说明此receiver是widget，widget提供者的详细定义在xml文件widget_provider中。里面定义了widget的宽高，更新时间以及布局文件等。

widget_provider文件

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:minWidth="70dp"
    android:minHeight="140dp"  
    android:updatePeriodMillis="86400000"
    android:initialLayout="@layout/widget"> 
</appwidget-provider>

以及layout文件widget。简单的两个按钮，音量加减。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <Button
        android:id="@+id/button_add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:textSize="14pt"
        android:text="+" />

    <Button
        android:id="@+id/button_reduce"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button_add"
        android:layout_below="@+id/button_add"
        android:textSize="14pt"
        android:text="-" />

</RelativeLayout>

接下来就是WidgetProvider类了，它继承了AppWidgetProvider。

其实一个AppWidgetProvider是一个BroadcastReceiver，仅仅是要实现几个函数：

1 public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds)
2 public void onDeleted(Context context, int[] appWidgetIds)
3 public void onEnabled(Context context)
4 public void onDisabled(Context context)

这几个函数用来响应AppWidget发出的对应的广播消息。他们的顺序是onEnabled ----> onUpdate ---> onDeleted ---> onDisabled。当你把widget放入桌面时，会运行onEnabled ----> onUpdate。然后到了定义的updatePeriodMillis时间时会运行一次Update，onUpdate方法会被调用，假设你从桌面删除widget则运行onDeleted ---> onDisabled方法。

在widget中对两个音量按钮设置监听器

public void onUpdate(Context context, int[] appIds) {
		System.out.println("update");
		
		RemoteViews rv = new RemoteViews(context.getApplicationContext().getPackageName(), R.layout.activity_main);  
        PendingIntent add = PendingIntent.getBroadcast(context, 0,  
        		new Intent("CLICK_ACTION_ADD") , 0);
        rv.setOnClickPendingIntent(R.id.button_add, add);
        PendingIntent reduce = PendingIntent.getBroadcast(context, 0, new Intent("CLICK_ACTION_REDUCE"), 0);
        rv.setOnClickPendingIntent(R.id.button_reduce, reduce);
        
        AppWidgetManager appWidgetManger = AppWidgetManager
				.getInstance(context);
		appWidgetManger.updateAppWidget(appIds, rv);
	}

这样按钮在点击的时候会发送CLICK_ACTION_ADD或者CLICK_ACTION_REDUCE广播，因此须要在AndroidManifest里面的receiver再增加两个intent-filter

<span style="white-space:pre">	</span>    <intent-filter>
                <action android:name="CLICK_ACTION_ADD"/>
            </intent-filter>
            <intent-filter>
                <action android:name="CLICK_ACTION_REDUCE"/>
            </intent-filter>

声音的控制用AudioManager来实现，其adjustVolume方法能够控制最相关音量依照一个方向改变，增大或减小

AudioManager AM;

AM = (AudioManager)context.getSystemService("audio");

AM.adjustVolume(AudioManager.ADJUST_LOWER, AudioManager.FLAG_SHOW_UI|AudioManager.FLAG_PLAY_SOUND);

后面的flag參数能够控制是否显示音量UI。以及更改时是否播放声音。

完整的WidgetProvider类

package com.frank.widgettest;

import android.app.PendingIntent;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.widget.RemoteViews;

public class WidgetProvider extends AppWidgetProvider{

	AudioManager AM;
	
	@Override
	public void onEnabled(Context context) {
		System.out.println("onEnabled");
		super.onEnabled(context);
	}
	
	@Override
	public void onUpdate(Context context, AppWidgetManager appWidgetManager,
			int[] appWidgetIds) {
		System.out.println("update");
		RemoteViews rv = new RemoteViews(context.getApplicationContext().getPackageName(), R.layout.widget);  
        PendingIntent add = PendingIntent.getBroadcast(context, 0,  
        		new Intent("CLICK_ACTION_ADD") , 0);
        rv.setOnClickPendingIntent(R.id.button_add, add);
        PendingIntent reduce = PendingIntent.getBroadcast(context, 0, new Intent("CLICK_ACTION_REDUCE"), 0);
        rv.setOnClickPendingIntent(R.id.button_reduce, reduce);
        
        AppWidgetManager appWidgetManger = AppWidgetManager
				.getInstance(context);
		appWidgetManger.updateAppWidget(appWidgetIds, rv);
		super.onUpdate(context, appWidgetManager, appWidgetIds);
	}
	
	@Override
	public void onReceive(Context context, Intent intent) {
		super.onReceive(context, intent);
		if (intent.getAction().equals("CLICK_ACTION_ADD")) {
            if(AM == null)
    			AM = (AudioManager)context.getSystemService("audio");
            AM.adjustVolume(AudioManager.ADJUST_RAISE, AudioManager.FLAG_SHOW_UI|AudioManager.FLAG_PLAY_SOUND);
        }
        
        if(intent.getAction().equals("CLICK_ACTION_REDUCE")){
        	if(AM == null)
        		AM = (AudioManager)context.getSystemService("audio");
        	AM.adjustVolume(AudioManager.ADJUST_LOWER, AudioManager.FLAG_SHOW_UI|AudioManager.FLAG_PLAY_SOUND);
        }
	}
	
	@Override
	public void onDeleted(Context context, int[] appWidgetIds) {
		System.out.println("deleted");
		super.onDeleted(context, appWidgetIds);
	}
}

2.BroadcastReceiver能够取代AppWidgetProvider

其实第一次尝试的时候不知什么原因不能监听收到widget的onEnabled，onUpdate全部事件。一筹莫展时，看到Android API Guides里这样一段话

既然如此，我干脆直接使用一个BroadcastReceiver来取代AppWidgetProvider试试看吧。

结果没问题，各响应都能够收到音量控制正常。

public class WidgetProvider extends BroadcastReceiver{
	
	AudioManager AM;
	
	public void onEnabled() {
		System.out.println("onEnabled");
	}
	
	public void onUpdate(Context context, int[] appIds) {
		System.out.println("update");
		
		RemoteViews rv = new RemoteViews(context.getApplicationContext().getPackageName(), R.layout.activity_main);  
        PendingIntent add = PendingIntent.getBroadcast(context, 0,  
        		new Intent("CLICK_ACTION_ADD") , 0);
        rv.setOnClickPendingIntent(R.id.button_add, add);
        PendingIntent reduce = PendingIntent.getBroadcast(context, 0, new Intent("CLICK_ACTION_REDUCE"), 0);
        rv.setOnClickPendingIntent(R.id.button_reduce, reduce);
        
        AppWidgetManager appWidgetManger = AppWidgetManager
				.getInstance(context);
		appWidgetManger.updateAppWidget(appIds, rv);
	}

	@Override
	public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals("CLICK_ACTION_ADD")) {
            if(AM == null)
    			AM = (AudioManager)context.getSystemService("audio");
            AM.adjustVolume(AudioManager.ADJUST_RAISE, AudioManager.FLAG_SHOW_UI|AudioManager.FLAG_PLAY_SOUND);
        }
        
        if(intent.getAction().equals("CLICK_ACTION_REDUCE")){
        	if(AM == null)
        		AM = (AudioManager)context.getSystemService("audio");
        	AM.adjustVolume(AudioManager.ADJUST_LOWER, AudioManager.FLAG_SHOW_UI|AudioManager.FLAG_PLAY_SOUND);
        }
        
        if (intent.getAction().equals(AppWidgetManager.ACTION_APPWIDGET_ENABLED)){
        	onEnabled();
        }
        
        if (intent.getAction().equals(AppWidgetManager.ACTION_APPWIDGET_UPDATE)){
        	int[] appWidgetIds = intent.getExtras().getIntArray(AppWidgetManager.EXTRA_APPWIDGET_IDS);
        	onUpdate(context, appWidgetIds);
        }
        
        if (intent.getAction().equals(AppWidgetManager.ACTION_APPWIDGET_DELETED)){
        	onDeleted();
        }
	}
	
	public void onDeleted() {
		System.out.println("deleted");
	}

由于逻辑方便定义的方法名也为AppWidgetProvider的方法名，也就是说用BroadcastReceiver能够做一个widget。

后来我又新建一个项目使用AppWidgetProvider（第一个方案）也成功运行。

转载请注明出处http://blog.csdn.net/franksun1991/article/details/26454043