FIREBASE_MESSAGING：当应用程序处于后台或已终止时，onBackgroundMessage 不处理通知

Question

I'm trying to get my onBackgroundMessage to execute when the app is on Background and a notification has been receive, but it doesn't execute myBackgroundMessageHandler.

I did everything that was written in the documentation at Optionally handle background messages, but it still doesn't work like i want, When i receive a notification when the app is on Background, What i get is a notification without data (no app icon and no images, only title and body text).Btw it's working well when the app is not onBackground

Here my code:

AndroidManifest.xml

<application
        android:name=".Application"

index.js

  message = {
    android: {
        notification: { click_action: 'FLUTTER_NOTIFICATION_CLICK',}
    },
    token: androidNotificationToken,
    data: {
      activityFeedItemId:activityFeedItemId,
      userReceivingNotificationId: userId,
      userActivatingNotificationPhotoUrl: activityFeedItem.userProfileImg,
      notificationType: activityFeedItem.type,
      body : body
    }
  };

buildgradle

dependencies {
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.google.firebase:firebase-analytics:17.2.2'
    implementation 'com.android.support:multidex:1.0.3'
    implementation 'com.google.firebase:firebase-messaging:20.1.7'
}

apply plugin: 'com.google.gms.google-services'

MainActivity.java

package com.yimerah.ijn_amen;
import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity;
import io.flutter.embedding.engine.FlutterEngine;
import io.flutter.plugins.GeneratedPluginRegistrant;

public class MainActivity extends FlutterActivity {
    @Override
    public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

Application.java

package com.yimerah.ijn_amen;

import io.flutter.app.FlutterApplication;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
import io.flutter.plugins.firebasemessaging.FlutterFirebaseMessagingService;
import io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin;

public class Application extends FlutterApplication implements PluginRegistrantCallback {
    @Override
    public void onCreate() {
        super.onCreate();
        FlutterFirebaseMessagingService.setPluginRegistrant(this);
    }

    @Override
    public void registerWith(PluginRegistry registry) {
        FirebaseMessagingPlugin.registerWith(registry.registrarFor("io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin"));
    }
}

OnBackgroundMessage

  onBackgroundMessage: myBackgroundMessageHandler
   static myBackgroundMessageHandler{
    final FirebaseUser firebaseUser = await auth.currentUser();

    print("on message:$message\n");
    final String userReceivingId =
        message['data']['userReceivingNotificationId'];
    final String body = message['data']['body'];
    final String notificationType = message['data']['notificationType'];
    final String notificationId = message['data']['activityFeedItemId'];
    if (userReceivingId == firebaseUser.uid) {
      int id = Uuid().parse(notificationId).reduce((a, b) => a + b);
        final String notificationMedia =
            message['data']['userActivatingNotificationPhotoUrl'];
        await showNotificationMediaStyle("", body, notificationMedia, id: id);


      print("Notification shown!");
    }
    print("Notification not shown!");
  }

Thank you in advance for your help,

Answer 1

When constructing a data notification, the notification payload MUST be blank.

If the notification payload is not empty, then the payload will be sent as a notification instead of a data message.

Answer 2

That is the expected behavior when the app is in the background, the notification goes directly to the Sytem Tray without onMessageReceived being called

More info: https://firebase.google.com/docs/cloud-messaging/android/receive