Android的Widget的定时刷新

Android的桌面小图标Widget有时候需要定时的刷新，而且updatePeriodMillis属性设置的时间是建议是1个小时。这个时间对有些功能就太长时间了。在开发者文档上面有建议用

AlarmManager

下面就是我写的一个小的Demo，让Widget上的ProgressBar以一秒钟progress增加一的速度更新。在onEnable中开一个定时器每秒唤醒WidgetUpdateReceiver一次做一次页面刷新。并且在onDisabled中将它取消。

 @Overridepublic void onEnabled(Context context) {//        Intent service = new Intent(context,WidgetUpdateService.class);//        context.startService(service);long firstTime = SystemClock.elapsedRealtime();firstTime += 1000;Intent receiver = new Intent();receiver.putExtra("FirstTime",firstTime);receiver.setAction(WidgetUpdateReceiver.ACTION);PendingIntent pendingIntent = PendingIntent.getBroadcast(context.getApplicationContext(), 2006, receiver, 0);AlarmManager am = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);am.setRepeating(AlarmManager.ELAPSED_REALTIME, firstTime, 1000, pendingIntent);Log.i(TAG, "onEnabled: ");super.onEnabled(context);}

 @Overridepublic void onDisabled(Context context) {//        Intent service = new Intent(context,WidgetUpdateService.class);//        context.stopService(service);Intent intent = new Intent();intent.setAction(WidgetUpdateReceiver.ACTION);PendingIntent pendingIntent = PendingIntent.getBroadcast(context.getApplicationContext(),2006,intent,0);AlarmManager am = (AlarmManager)context.getSystemService(Context.ALARM_SERVICE);am.cancel(pendingIntent);Log.i(TAG, "onDisabled: ");super.onDisabled(context);}

public class WidgetUpdateReceiver extends BroadcastReceiver {public static String TAG = "WidgetUpdateReceiver";public static final String ACTION = "android.appwidget.action.PROGRESS_UPDATE";@Overridepublic void onReceive(Context context, Intent intent) {Log.i(TAG, "onReceive: ");//        receiver.putExtra("FirstTime",firstTime);long currentTime = SystemClock.elapsedRealtime();long firstTime = intent.getLongExtra("FirstTime", SystemClock.elapsedRealtime());int progress = (int)(currentTime-firstTime)/1000;if (progress > 100){Toast.makeText(context,"progress到100了",Toast.LENGTH_SHORT).show();progress = 100;}AppWidgetManager am = AppWidgetManager.getInstance(context);//Widget是在其他应用上面显示的所以要用RemoteViews来管理RemoteViews remoteViews = new RemoteViews(context.getPackageName(),R.layout.my_widget);Intent i = new Intent(context,MainActivity.class);PendingIntent pendingIntent = PendingIntent.getActivity(context,2016,i,0);//设置点击图片的点击事件，打开一个ActivityremoteViews.setOnClickPendingIntent(R.id.iv, pendingIntent);remoteViews.setProgressBar(R.id.progressBar,100,progress,false);ComponentName name = new ComponentName(context,MyWidget.class);am.updateAppWidget(name,remoteViews);}}

在这个Receiver中就可以做一些刷新Widget的操作。