Java 不使用FirebaseMessaging接收前台通知，但在后台工作

我添加了一个FirebaseMessagingService类来接收前台通知。 我没有收到前台通知。 在后台，当应用程序最小化时，它工作正常

我已经用firebase函数设置了后台通知，它工作得很好，现在我试图在前台获取此通知，但通知没有出现

我的FirebaseMessagingService类：

public class FirebaseMessaging extends FirebaseMessagingService {


    @Override
    public void onMessageReceived(@NonNull RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);
        if (remoteMessage.getNotification() != null) {
            String notification_title = remoteMessage.getNotification().getTitle();
            String notification_message = remoteMessage.getNotification().getBody();

            Notification.Builder mBuilder = new Notification.Builder(this)
                    .setContentTitle(notification_title)
                    .setContentText(notification_message)
                    .setSmallIcon(R.drawable.default_avatar);

            int mNotificationId = (int) System.currentTimeMillis();

            NotificationManager mNotifyMgr = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            mNotifyMgr.notify(mNotificationId, mBuilder.build());
        }
    }
}

无错误消息：

实际结果：通知从未到达前台。

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预期结果：我希望在应用程序中即时通讯时收到通知，而不仅仅是最小化时。

我将FirebaseMEssagingService类更改为它工作时的状态：

public class FirebaseMessaging extends FirebaseMessagingService {
private final String CHANNEL_ID = "personal_notifications";
@Override
public void onMessageReceived(@NonNull RemoteMessage remoteMessage) {
    super.onMessageReceived(remoteMessage);

    NotificationManager mNotifyMgr = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

    String notification_title = remoteMessage.getNotification().getTitle();
    String notification_message = remoteMessage.getNotification().getBody();

    NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        NotificationChannel notificationChannel = new NotificationChannel(CHANNEL_ID, "My Notifications", NotificationManager.IMPORTANCE_HIGH);

        NotificationCompat.Builder mBuilder =
                new NotificationCompat.Builder(this, CHANNEL_ID)
                        .setSmallIcon(R.drawable.default_avatar)
                        .setContentTitle(notification_title)
                        .setContentText(notification_message);

        notificationManager.createNotificationChannel(notificationChannel);

        int mNotificationId = (int) System.currentTimeMillis();
        mNotifyMgr.notify(mNotificationId, mBuilder.build());
    }
}

}