Firebase OnMessage function refreshes widget

问题

I am using firebase cloud messaging to push notification on my app that contains a chat page.

I defined my firebase push functions on my main.dart as below:

_firebaseMessaging.configure(
   onMessage: (Map<String, dynamic> message) async {
     print("onMessage: $message");
     //_showItemDialog(message);
   },
   onBackgroundMessage: myBackgroundMessageHandler,
   onLaunch: (Map<String, dynamic> message) async {
     print("onLaunch: $message");
     //_navigateToItemDetail(message);
   },
   onResume: (Map<String, dynamic> message) async {
     print("onResume: $message");
     //_navigateToItemDetail(message);
   },
 );

When chat widget opened and i receive a push notification, my OnMessage method is reached normally.

The question is: what is the best way to refresh my chat page considering that the opened page is not the same one where the reached OnMessage function is declared?

回答1:

I have used following peice of code for different question on StackOverflow. But the problem there is entirely different from yours, so pasting relevant code.

You can use BLOC here. FCM/NotificationService will send notifications to BLOC/NotificationsBloc and all the widgets that need notifications can subscribe for the notifications. Sample implementation

BLOC

import 'package:rxdart/rxdart.dart';

class LocalNotification {
  final String type;
  final Map data;

  LocalNotification(this.type, this.data);
}

class NotificationsBloc {
  NotificationsBloc._internal();

  static final NotificationsBloc instance = NotificationsBloc._internal();

  final BehaviorSubject<LocalNotification> _notificationsStreamController = BehaviorSubject<LocalNotification>();

  Stream<LocalNotification> get notificationsStream {
    return _notificationsStreamController;
  }

  void newNotification(LocalNotification notification) {
    _notificationsStreamController.sink.add(notification);
  }

  void dispose() {
    _notificationsStreamController?.close();
  }
}

FCM Listener (NotificationService)

import 'package:firebase_messaging/firebase_messaging.dart';

import 'notifications_bloc.dart';

class LocalNotificationService {
  final FirebaseMessaging _firebaseMessaging = FirebaseMessaging();
  bool _started = false;

  LocalNotificationService._internal();

  static final LocalNotificationService instance = LocalNotificationService._internal();

  // ********************************************************* //
  // YOU HAVE TO CALL THIS FROM SOMEWHERE (May be main widget)
  // ********************************************************* //
  void start() {
    if (!_started) {
      _start();
      _started = true;
      _refreshToken();
    }
  }

  void _refreshToken() {
    _firebaseMessaging.getToken().then(_tokenRefresh, onError: _tokenRefreshFailure);
  }

  void _start() {
    _firebaseMessaging.requestNotificationPermissions();
    _firebaseMessaging.onTokenRefresh.listen(_tokenRefresh, onError: _tokenRefreshFailure);
    _firebaseMessaging.configure(
      onMessage: _onMessage,
      onLaunch: _onLaunch,
      onResume: _onResume,
    );
  }

  void _tokenRefresh(String newToken) async {
    print(" New FCM Token $newToken");
  }

  void _tokenRefreshFailure(error) {
    print("FCM token refresh failed with error $error");
  }

  Future<void> _onMessage(Map<String, dynamic> message) async {
    print("onMessage $message");
    if (message['notification'] != null) {
      final notification = LocalNotification("notification", message['notification'] as Map);
      NotificationsBloc.instance.newNotification(notification);
      return null;
    }
    if (message['data'] != null) {
      final notification = LocalNotification("data", message['data'] as Map);
      NotificationsBloc.instance.newNotification(notification);
      return null;
    }
  }

  Future<void> _onLaunch(Map<String, dynamic> message) {
    print("onLaunch $message");
    return null;
  }

  Future<void> _onResume(Map<String, dynamic> message) {
    print("onResume $message");
    return null;
  }
}

Finally in your Widget

  Stream<LocalNotification> _notificationsStream;

  @override 
  void initState() {
    super.initState();
    _notificationsStream = NotificationsBloc.instance.notificationsStream;
    _notificationsStream.listen((notification) {
      // TODO: Implement your logic here
      print('Notification: $notification');
    });
  }

  @override
  void dispose() {
    _notificationsStream?.dispose();
  }

Hope this is what you are looking for.

来源：https://stackoverflow.com/questions/58207747/firebase-onmessage-function-refreshes-widget