Question

在我的应用程序中，对于Web版本，我将软件包firebase 7.3.0用于Firebase服务，并且现在也正在为Web设置FCM。当我在前台使用该应用收到新消息时，来自onMessage:的{{1}}被触发两次。在某些Flutter版本之前，messaging()设备插件也曾经发生过这种情况，但现在已解决。

我基本上设置了一个flutter_messaging来获取与StreamTransformer中使用的Map<String, dynamic>设备包相同类型的flutter_messaging消息，我使用一个Stub来切换类取决于平台。在网络类PlatformPushNotificationDevice中，我将消息传递实例化为PlatformPushNotificationWeb并声明了我的方法，其中之一是var firebaseMessaging = messaging();：

onMessage()

所以无论平台如何，我集团中的侦听器都将收到相同的消息类型，

Stream<Map<String, dynamic>> onMessage()  async* {

    print('PlatformPushNotificationWeb.onMessage() started');
    handleData(Payload payload, EventSink<Map<String, dynamic>> sink) {
        Map<String,dynamic> message = {
          'notification': {
            'title': payload.notification.title,
            'body': payload.notification.body,
            'sound': true
          },
          'data': payload.data
        };
      sink.add(message);
    }

    final transformer = StreamTransformer<Payload, Map<String, dynamic>>.fromHandlers(
        handleData: handleData);

    yield* firebaseMessaging.onMessage.transform(transformer);
  }

但是对于每条传入的消息，我都会让侦听器响应两次。

我将Stream<PushNotificationState> _mapListenToMessagesToState(ListenToMessages event) async* { print('_mapListenToMessagesToState started'); _pushNotificationSwitcher.onMessage().listen((message) { print('_mapListenToMessagesToState onMessage() listener: received new message'); add(ReceivedNewMessage(message: message)); }); }设置为：

index.html

和<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>fixit cloud biking</title>  <meta name="google-signin-client_id" content="xxxx.apps.googleusercontent.com">  </head>  <body id="app-container"> <script src="main.dart.js?version=45" type="application/javascript"></script>  <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-app.js"></script>  <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-auth.js"></script> <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-analytics.js"></script> <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-messaging.js"></script> <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-storage.js"></script> <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-database.js"></script> <script src="https://www.gstatic.com/firebasejs/7.19.1/firebase-remote-config.js"></script> <script> if ("serviceWorker" in navigator) { window.addEventListener("load", function () { //navigator.serviceWorker.register("/flutter_service_worker.js"); navigator.serviceWorker.register("/firebase-messaging-sw.js"); }); } </body> </html>文件为：

firebase-messaging-sw.js

是否可能是在importScripts("https://www.gstatic.com/firebasejs/7.19.1/firebase-app.js"); importScripts("https://www.gstatic.com/firebasejs/7.19.1/firebase-messaging.js"); firebase.initializeApp({ apiKey: "xxxx", authDomain: "xxxx", databaseURL: "xxxx", projectId: "xxx", storageBucket: "xxxx", messagingSenderId: "xxxx", appId: "xxx", measurementId: "G-xxxx", }); const messaging = firebase.messaging(); messaging.setBackgroundMessageHandler(function (payload) { console.log('[firebase-messaging-sw.js] Received background message ', payload); const promiseChain = clients .matchAll({ type: "window", includeUncontrolled: true }) .then(windowClients => { for (let i = 0; i < windowClients.length; i++) { const windowClient = windowClients[i]; windowClient.postMessage(payload); } }) .then(() => { return registration.showNotification("New Message"); }); return promiseChain; }); self.addEventListener('notificationclick', function (event) { console.log('notification received: ', event) });类和PlatformPushNotificationWeb文件中实例化消息传递导致firebase-messaging-sw.js回调被触发两次的原因？非常感谢。

Answer 1

事实证明..很好的清理，Android Studio和机器重启解决了这个问题。

现在我不会两次收到相同的消息，但是对于那些实际上正在尝试重复消息的人来说，这将解决该问题，但这只是一种解决方法。

只需声明int lastMessageId = 0变量。收到邮件时，请对照其id进行检查，并且只有它们不同时，才将新的邮件ID保存为lastMessageId并显示该邮件。

Stream<PushNotificationState> _mapListenToMessagesToState(ListenToMessages event) async* {
    print('_mapListenToMessagesToState started');
    int lastMessageId = 0;

    _pushNotificationSwitcher.onMessage().listen((message) {
      print('incoming message is : $message');
      var data = message['data'];
      int messageId = int.parse(data['id']);

      if( lastMessageId != messageId) {
        lastMessageId = messageId;
        print(
            '_mapListenToMessagesToState onMessage() listener: received new message');
        add(ReceivedNewMessage(message: message));
      }
    });
  }

onMessage：在传入消息上两次调用回调

1 个答案: