Question

我正在开发一款必须在后台执行2项定期任务的Android应用程序：

每24小时从服务器下载文件。
每周在手机SD卡上执行文件操作。

我该怎么做？

Answer 1

首先，您需要使用 AlarmManager 。当注册的警报例如24小时的情况下，将触发，您可以从AlarmManager的广播接收器呼叫服务。如果你还不知道，你需要研究一下AlarmManager。如需进一步的帮助，您可以从下面的代码中获得一些想法：

Calendar cur_cal = new GregorianCalendar();
cur_cal.setTimeInMillis(System.currentTimeMillis());
Calendar cal = new GregorianCalendar();
cal.set(Calendar.DAY_OF_YEAR, cal.get(Calendar.DAY_OF_YEAR) + 1); //+1 For Next day (24 hours or so...)
cal.set(Calendar.HOUR_OF_DAY,  hour);
cal.set(Calendar.MINUTE, minute);
cal.set(Calendar.SECOND, cur_cal.get(Calendar.SECOND));
cal.set(Calendar.MILLISECOND, cur_cal.get(Calendar.MILLISECOND));
cal.set(Calendar.DATE, cur_cal.get(Calendar.DATE));
cal.set(Calendar.MONTH, cur_cal.get(Calendar.MONTH));

AlarmManager am = (AlarmManager)getApplicationContext().getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(getApplicationContext(), AlarmReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 0, intent, PendingIntent.FLAG_ONE_SHOT);
am.cancel(pendingIntent);
am.set(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), pendingIntent);

以下是设置闹钟的方法。现在，当触发警报时，您将按照以下方式致电您的服务：

public class AlarmReceiver extends BroadcastReceiver
{   
   @Override
   public void onReceive(Context arg0, Intent arg1)
   {    
           // Call you service or any task here
   }
}

最后，请不要忘记在AndroidManifest.xml中提及您的广播接收器和服务

<receiver android:name=".AlarmReceiver">
</receiver>    
<service android:name=".MyService"/>

Answer 2

以下是关于AlarmManager

的官方Android文档

Note: The Alarm Manager is intended for cases where you want to have 
your application code run at a specific time, even if your application 
is not currently running. For normal timing operations (ticks, timeouts, etc) 
it is easier and much more efficient to use Handler.

Handler文档。

服务定期工作

2 个答案: