如何實現定期查詢數據庫並定期刪除行的任務？

Question

如何實現定期查詢數據庫並定期刪除行的任務？我想這樣做，以便防止我的數據庫隨着時間的推移變得太大。

Answer 1

使用粘滯Service與AlarmManager和BroadcastReceiver是你所需要的。

public class MY_SERVICE extends Service { 

@Override 
public int onStartCommand(Intent intent, int flags, int startId) { 

    // remove last alarm you set 
    Intent intent = new Intent(context, MY_DB_PROCEDURE_BROADCAST.class); 
    intent.setAction("myDbProcedure"); 
    PendingIntent alarmIntent = PendingIntent.getBroadcast(context,1, intent, PendingIntent.FLAG_UPDATE_CURRENT); 
    AlarmManager alarmMgr = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); 
    alarmMgr.cancel(alarmIntent); 

    // add new alarm manager 
    intent = new Intent(context, MY_DB_PROCEDURE_BROADCAST.class); 
    intent.setAction("myDbProcedure"); 
    alarmIntent = PendingIntent.getBroadcast(ct, 1, intent, 0); 
    alarmMgr = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE); 
    alarmMgr.setRepeating(AlarmManager.RTC_WAKEUP, Calendar.getInstance().getTimeInMillis(), 
      intervalMin*60*1000, alarmIntent); 

    return START_STICKY; 
} 

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

}

您BroadcastReceiver類：

public class MY_DB_PROCEDURE_BROADCAST extends BroadcastReceiver { 

    private final String TAG=getClass().getName(); 

    @Override 
    public void onReceive(Context context, Intent intent) { 
     Log.i(TAG,"Started"); 
     // DO YOUR DB TASK HERE 
    } 

}

在您的清單定義服務和廣播接收器：

<service 
     android:name="MY_SERVICE" 
     android:enabled="true" 
     android:exported="true" /> 

<receiver android:name="MY_DB_PROCEDURE_BROADCAST" android:enabled="true"/>