private ActivityManager activityManager;

	activityManager = (ActivityManager) mcontext.getSystemService(Context.ACTIVITY_SERVICE);

 	IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_OFF);
	filter.addAction(Intent.ACTION_SCREEN_ON);
	registerReceiver(mBatInfoReceiver, filter);

   private final 
 
BroadcastReceiver mBatInfoReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(final Context context, final Intent intent) {
            final String action = intent.getAction();
            if (Intent.ACTION_SCREEN_OFF.equals(action)) {
                activityManager
 
.moveTaskToFront(Activity（你的activity）).getTaskId(), 1);
            } else if (Intent.ACTION_SCREEN_ON.equals(action)) {
//                
                (Activity（你的activity）).moveTaskToBack(true);
            }
        }
    };