/**
 * Method checks if the app is in background or not
 */
public static boolean isAppIsInBackground(Context context) {
    boolean isInBackground = true;
    ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
    if (Build.VERSION.SDK_INT > Build.VERSION_CODES.KITKAT_WATCH) {
        List<ActivityManager.RunningAppProcessInfo> runningProcesses = am.getRunningAppProcesses();
        for (ActivityManager.RunningAppProcessInfo processInfo : runningProcesses) {
            if (processInfo.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
                for (String activeProcess : processInfo.pkgList) {
                    if (activeProcess.equals(context.getPackageName())) {
                        isInBackground = false;
                    }
                }
            }
        }
    } else {
        List<ActivityManager.RunningTaskInfo> taskInfo = am.getRunningTasks(1);
        ComponentName componentInfo = taskInfo.get(0).topActivity;
        if (componentInfo.getPackageName().equals(context.getPackageName())) {
            isInBackground = false;
        }
    }

    return isInBackground;
}

您可以检查应用程序是否在后台运行，然后在MyFirebaseMessagingService类中可以使用此方法处理消息和处理通知.

You can check app is in the background or not and then in MyFirebaseMessagingService class you can use this method in for handle message and handle the notification.

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 the app is in background, firebase itself handles the notification
    }
}

希望对您有帮助.