生成APK时Firebase推送通知

Question

在我的应用程序中，我需要成功应用的推送通知功能。它也显示在模拟器中的应用程序上，但是我生成了签名的apk或构建的apk，然后在我的应用程序中使用，然后通过firebase使用云消息传递，但未显示通知。为什么？

import android.util.Log;

import com.google.firebase.messaging.FirebaseMessagingService;
import com.google.firebase.messaging.RemoteMessage;

public class MyFirebaseMessagingService extends FirebaseMessagingService {
private static final String TAG = "FCM Service";

@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
    // TODO: Handle FCM messages here.
    // If the application is in the foreground handle both data and notification messages here.
    // Also if you intend on generating your own notifications as a result of a received FCM
    // message, here is where that should be initiated.
    Log.d(TAG, "From: " + remoteMessage.getFrom());
    Log.d(TAG, "Notification Message Body: " + remoteMessage.getNotification().getBody());
}

}

import android.util.Log;

import com.google.firebase.iid.FirebaseInstanceId;
import com.google.firebase.iid.FirebaseInstanceIdService;

public class FirebaseIDService extends FirebaseInstanceIdService {

    private static final String TAG = "FirebaseIDService";
@Override
public void onTokenRefresh() {
    // Get updated InstanceID token.
    String refreshedToken = FirebaseInstanceId.getInstance().getToken();
    Log.d(TAG, "Refreshed token: " + refreshedToken);

    // TODO: Implement this method to send any registration to your app's servers.
    sendRegistrationToServer(refreshedToken);
}

/**
 * Persist token to third-party servers.
 *
 * Modify this method to associate the user's FCM InstanceID token with any server-side account
 * maintained by your application.
 *
 * @param token The new token.
 */
private void sendRegistrationToServer(String token) {
    // Add custom implementation, as needed.
}

}