Android下Firebase云消息推送通知前台不起作用，后台起作用

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        super.onMessageReceived(remoteMessage);

        // 处理通知消息
        if (remoteMessage.getNotification() != null) {
            showNotification(remoteMessage.getNotification().getTitle(), remoteMessage.getNotification().getBody());
        }
    }

    private void showNotification(String title, String message) {
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "your_channel_id")
                .setContentTitle(title)
                .setContentText(message)
                .setSmallIcon(R.drawable.ic_notification)
                .setPriority(NotificationCompat.PRIORITY_HIGH);

        NotificationManagerCompat notificationManager = NotificationManagerCompat.from(this);
        notificationManager.notify(0, builder.build());
    }

    @Override
    public void onCreate() {
        super.onCreate();
        startForeground(1, new NotificationCompat.Builder(this, "your_channel_id")
                .setContentTitle("My App")
                .setContentText("App is running in foreground")
                .setSmallIcon(R.drawable.ic_notification)
                .build());
    }
}

private void createNotificationChannel() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        CharSequence name = "My App Channel";
        String description = "Channel for My App notifications";
        int importance = NotificationManager.IMPORTANCE_HIGH;
        NotificationChannel channel = new NotificationChannel("your_channel_id", name, importance);
        channel.setDescription(description);

        NotificationManager notificationManager = getSystemService(NotificationManager.class);
        notificationManager.createNotificationChannel(channel);
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    createNotificationChannel();
}

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-pertype="android.permission.VIBRATE" />