AppWidget的使用

1在配置文件中注册AppWidget,生成相应的AppWidgetProvider子类

<receiver android:name=".receiver.MyAppWidgetProvider">
    <intent-filter>
        <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
    </intent-filter>
    <meta-data android:name="android.appwidget.provider"
        android:resource="@xml/appwidget_info"/>
</receiver>

public class MyAppWidgetProvider extends AppWidgetProvider {
    //下面每个方法被调用前都会调用此方法
    @Override
    public void onReceive(Context context, Intent intent) {
        super.onReceive(context, intent);
    }
 //第一个widget创建
    @Override
    public void onEnabled(Context context) {
        /*开启相同的服务，只调用onCreate方法一次，在onCreate方法里进行监听widget的ui更新。
         避免进行多次监听,用计时器和RemoteView,AppWidgetManager进行监听。在下面函数都开启服务。这样就避免多次避免服务被杀死,
         */
        context.startService(new Intent(context, UpdateWidgetService.class));
        super.onEnabled(context);
    }
   //widget个数添加
    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        context.startService(new Intent(context, UpdateWidgetService.class));
        super.onUpdate(context, appWidgetManager, appWidgetIds);
    }
    //widget配置改变时，widget宽高或者widget个数增加
    @Override
    public void onAppWidgetOptionsChanged(Context context, AppWidgetManager appWidgetManager, int appWidgetId, Bundle newOptions) {
        context.startService(new Intent(context, UpdateWidgetService.class));
        super.onAppWidgetOptionsChanged(context, appWidgetManager, appWidgetId, newOptions);
    }

    //最后一个widget关闭
    @Override
    public void onDisabled(Context context) {
        context.stopService(new Intent(context, UpdateWidgetService.class));
        super.onDisabled(context);
    }
   //关闭一个widget
    @Override
    public void onDeleted(Context context, int[] appWidgetIds) {
        super.onDeleted(context, appWidgetIds);
    }
}

2定义AppWidget的属性xml文件

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    android:minWidth = "294dp"
    android:minHeight = "72dp"
    android:initialLayout ="@layout/appwidget"/>

注意，在res下的xml文件夹中定义

3定义AppWidget对应的布局文件

支持LinearLayout,RelativeLayout,FrameLayout三种ViewGroup

及常用的一些控件,具体见

4在注册的Appwidget类中开启服务来更新UI,用RemoteViews。

public class UpdateWidgetService extends Service {
    private Context mContext;
    private Timer timer;
    private InnerReceiver innerReceiver;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        mContext=this;
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(Intent.ACTION_SCREEN_OFF);
        intentFilter.addAction(Intent.ACTION_SCREEN_ON);
        innerReceiver = new InnerReceiver();
        registerReceiver(innerReceiver,intentFilter);
         startTimer();
        super.onCreate();
    }
      class InnerReceiver extends BroadcastReceiver
      {

          @Override
          public void onReceive(Context context, Intent intent) {
              if(intent.getAction().equals(Intent.ACTION_SCREEN_ON))
              {
                  startTimer();
              }
              else
              {
                  if(timer!=null) {
                      timer.cancel();
                      timer = null;
                  }
              }
          }
      }


    private void startTimer() {
        //定时器更新
        timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                //获取AppWidgetManager对象
                AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(mContext);
                //获得远程View。窗体小控件的View
                RemoteViews remoteViews = new RemoteViews(getPackageName(), R.layout.appwidget);

                Intent intent = new Intent("android.intent.action.HOME");
                intent.addCategory("android.intent.category.DEFAULT");
                PendingIntent pendingIntent = PendingIntent.getActivity(mContext,0,intent,PendingIntent.FLAG_CANCEL_CURRENT);
                remoteViews.setOnClickPendingIntent(R.id.app_linear,pendingIntent);
                //设置按钮点击事件,杀进程通过广播接收者来处理
                Intent intent1 = new Intent("android.intent.action.KILL_BACKGROUD_PROCESS");
                intent1.addCategory("android.intent.category.DEFAULT");
                PendingIntent pendingIntent1 = PendingIntent.getActivity(mContext,0,intent1,PendingIntent.FLAG_CANCEL_CURRENT);
                remoteViews.setOnClickPendingIntent(R.id.appbtn_clear,pendingIntent1);
                //设置对应的View内容
                remoteViews.setTextViewText(R.id.process_count,"进程总数:"+ ProgressInfoUtil.getProgressCount(mContext));
                remoteViews.setTextViewText(R.id.process_memory,"可用内存:"+ProgressInfoUtil.getAvailSpace(mContext));

                //窗体小部件对应广播接收者的字节码文件
                ComponentName componentName = new ComponentName(mContext, MyAppWidgetProvider.class);
                //更新窗体小部件
                appWidgetManager.updateAppWidget(componentName,remoteViews);
            }
        },0,5000);
    }

    @Override
    public void onDestroy() {
        if(innerReceiver!=null)
            unregisterReceiver(innerReceiver);
        timer.cancel();
        timer=null;
        super.onDestroy();
    }

注：更新频率必须大于半小时。