Question

I m looking for the best practice to implement a service for logging gps- or other sensor-values periodically (every 10-60 sec). The service should deal with the standby mode, when the phone goes asleep.

Any help, even pseudo-code, is very much appreciated!

Answer 1

It looks like it is impossible to let the orientation sensors work constantly for hours even though the device may fall asleep (refer to http://code.google.com/p/android/issues/detail?id=3708#makechanges

As soon as the display goes off, the sensors will do alike… 🙁

I now implemented a wakelock (needs permission)

<uses-permission android:name="android.permission.WAKE_LOCK" /> 

in conjunction with a timer and a broadcastreciever that will turn the display back on again. This is of course crazy for battery life but I found no other way so far.

This is my onCreate method in the service:

@Override
public void onCreate() {
mNM = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
CONTEXT = this;
PowerManager pm = (PowerManager) CONTEXT.getSystemService(Context.POWER_SERVICE);
this.mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "my tag");
mWakeLock.acquire();
Log.d(TAG, "Wakelock acquired");
// register receiver that handles screen on and screen off logic
            IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
            filter.addAction(Intent.ACTION_SCREEN_OFF);
            BroadcastReceiver mReceiver = new ScreenReceiver();
            registerReceiver(mReceiver, filter);
}

this the onStart method of the service:

@Override
public void onStart(Intent intent, int startid) {
Toast.makeText(this, "My Service Started", Toast.LENGTH_SHORT).show();
Log.d(TAG, "onStart");
boolean screenOn = intent.getBooleanExtra("screen_state", false);
            if (!screenOn) {
                Log.d(TAG, "Screen is on");
            } else {
             Log.d(TAG, "Screen is off");
         Timer timer = new Timer("DigitalClock");
     timer.schedule(new TimerTask() {
        @Override
        public void run() {
         Log.d(TAG,"Waiting 1 sec for switching the screen back on again...");
     PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
     mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP,
         "my tag");
     mWakeLock.acquire();
        }
     }, 1000);
             mWakeLock.acquire();
                }
}

and this is the BroadcastReceiver class:

public class ScreenReceiver extends BroadcastReceiver {
     private boolean screenOff;
     @Override
     public void onReceive(Context context, Intent intent) {
             if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
                     screenOff = true;
             } else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
                     screenOff = false;
             }
             Intent i = new Intent(context, MyService.class);
             i.putExtra("screen_state", screenOff);
             context.startService(i);
     }

}

This workaround will also do with a device UN-plugged from the debugger via USB (I first had an issue with this).

Please let me know if you have a better solution, or if there is fix in 2.3. Thanx!