我正在重构一些代码,使我的应用程序能够在指定的时间每天从网站中拉取数据。根据我的研究,似乎使用 AlarmManager
是最合适的方法。
我一直在遵循的教程是:http://mobile.tutsplus.com/tutorials/android/android-fundamentals-downloading-data-with-services/
到目前为止,AlarmManager
和 BroadcastReceiver
似乎都正常工作,但是 Service
似乎从未启动过(即 onStartCommand
似乎从未被调用)
以下是我目前所拥有的重要代码片段:
MyActivity.java
private void setRecurringAlarm(Context context) {
Calendar updateTime = Calendar.getInstance();
updateTime.setTimeZone(TimeZone.getDefault());
updateTime.set(Calendar.HOUR_OF_DAY, 20);
updateTime.set(Calendar.MINUTE, 30);
Intent downloader = new Intent(context, AlarmReceiver.class);
downloader.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, downloader, PendingIntent.FLAG_CANCEL_CURRENT);
AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
// should be AlarmManager.INTERVAL_DAY (but changed to 15min for testing)
alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, updateTime.getTimeInMillis(), AlarmManager.INTERVAL_FIFTEEN_MINUTES, pendingIntent);
Log.d("MyActivity", "Set alarmManager.setRepeating to: " + updateTime.getTime().toLocaleString());
}
AlarmReceiver.java
public class AlarmReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Intent dailyUpdater = new Intent(context, MyService.class);
context.startService(dailyUpdater);
Log.d("AlarmReceiver", "Called context.startService from AlarmReceiver.onReceive");
}
}
MyService.java
public class MyService extends Service {
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d("MyService", "About to execute MyTask");
new MyTask().execute();
return Service.START_FLAG_REDELIVERY;
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
private class MyTask extends AsyncTask<String, Void, boolean> {
@Override
protected boolean doInBackground(String... strings) {
Log.d("MyService - MyTask", "Calling doInBackground within MyTask");
return false;
}
}
}
AndroidManifest.xml
<application ...>
...
<service android:name="MyService"></service>
<receiver android:name="AlarmReceiver"></receiver>
</application>
当我在MyActivity
中触发setRecurringAlarm
时,日志按预期打印,同样地,每15分钟从AlarmReceiver
的日志也会显示。 但是,我从未看到MyService
的日志:(
以下是我在日志中看到的示例:
DEBUG/MyActivity(688): Set alarmManager.setRepeating to: Jan 29, 2012 8:30:06 PM
DEBUG/AlarmReceiver(688): Called context.startService from AlarmReceiver.onReceive
DEBUG/AlarmReceiver(688): Called context.startService from AlarmReceiver.onReceive
我似乎找不出做错了什么——根据Android Dev Docs,当我在AlarmReceiver
中调用context.startService(dailyUpdater)
时,应该会依次调用MyService
中的onStartCommand
方法,但实际上并非如此!
是什么导致MyService
根本没有启动呢?