public void playNotificationSound() {
        try {

            Uri notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
            Ringtone r = RingtoneManager.getRingtone(mContext,notification);
            r.play();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

我正在调用这个OnMessageReceived方法,但声音仅在应用程序处于前台时播放,而不是在应用程序处于后台时播放

@Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        Log.e(TAG,"From: " + remoteMessage.getFrom());

        if (remoteMessage == null)
            return;

        // Check if message contains a notification payload.
        if (remoteMessage.getNotification() != null) {
            Log.e(TAG,"Notification Body: " + remoteMessage.getNotification().getBody());
            handleNotification(remoteMessage.getNotification().getBody());
        }

        // Check if message contains a data payload.
        if (remoteMessage.getData().size() > 0) {
            Log.e(TAG,"Data Payload: " + remoteMessage.getData().toString());

            try {
                JSONObject json = new JSONObject(remoteMessage.getData().toString());
                handleDataMessage(json);
            } catch (Exception e) {
                Log.e(TAG,"Exception: " + e.getMessage());
            }
        }
    }





 private void handleNotification(String message) {
        if (!NotificationUtils.isAppIsInBackground(getApplicationContext())) {
            // app is in foreground,broadcast the push message
            Intent pushNotification = new Intent(config.PUSH_NOTIFICATION);
            pushNotification.putExtra("message",message);
            LocalBroadcastManager.getInstance(this).sendBroadcast(pushNotification);

            // play notification sound
            NotificationUtils notificationUtils = new NotificationUtils(getApplicationContext());
            notificationUtils.playNotificationSound();
        }else if (NotificationUtils.isAppIsInBackground(getApplicationContext())){
            // If the app is in background,firebase itself handles the notification
            NotificationUtils notificationUtils = new NotificationUtils(getApplicationContext());
            notificationUtils.playNotificationSound();
        }
    }