问题描述

我在我的 Flutter 应用程序中使用 firebase_messaging 库进行 Firebase 推送通知.

i am using firebase_messaging library in My Flutter Application for Firebase Push Notifications.

目前我的 firebase_messaging 版本是 firebase_messaging: ^5.1.5，最近更新为最新版本.

Currently my firebase_messaging version is firebase_messaging: ^5.1.5 which was recently updated an the latest one.

我正在尝试在后台以及应用程序终止时接收通知.

i am trying to receive notification in background as well as when application is terminated.

我已按照 firebase_messaging 文档中提到的所有步骤进行操作，但不幸的是，我在 Flutter 中遇到了上述错误.

i have followed all the steps as mentioned in the documentation of firebase_messaging but unfortunately i am getting the above error in flutter.

这是我在 dart 中的通知处理程序类

this is my notification handler class in dart

notification_handler.dart

import 'dart:async';
import 'dart:io';
import 'dart:math';

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:path_provider/path_provider.dart';
import 'package:http/http.dart' as http;

class NotificationHandler {
  FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;
  FirebaseMessaging _fcm = FirebaseMessaging();
  StreamSubscription iosSubscription;
  static final NotificationHandler _singleton =
      new NotificationHandler._internal();

  factory NotificationHandler() {
    return _singleton;
  }
  NotificationHandler._internal();

  Future<dynamic> myBackgroundMessageHandler(
      Map<String, dynamic> message) async {
    print("onLaunch: $message");
    _showBigPictureNotification(message);
    // Or do other work.
  }

  initializeFcmNotification() async {
    flutterLocalNotificationsPlugin = new FlutterLocalNotificationsPlugin();

    var initializationSettingsAndroid =
        new AndroidInitializationSettings('ic_launcher');
    var initializationSettingsIOS = new IOSInitializationSettings(
        onDidReceiveLocalNotification: onDidReceiveLocalNotification);
    var initializationSettings = new InitializationSettings(
        initializationSettingsAndroid, initializationSettingsIOS);
    flutterLocalNotificationsPlugin.initialize(initializationSettings,
        onSelectNotification: onSelectNotification);

    if (Platform.isIOS) {
      iosSubscription = _fcm.onIosSettingsRegistered.listen((data) {
        // save the token  OR subscribe to a topic here
      });

      _fcm.requestNotificationPermissions(IosNotificationSettings());
    } else {
      _saveDeviceToken();
    }

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

  /// Get the token, save it to the database for current user
  _saveDeviceToken() async {
    String fcmToken = await _fcm.getToken();
    print("FCM_TOKEN: $fcmToken");
  }

  Future<void> _showBigPictureNotification(message) async {
    var rng = new Random();
    var notifId = rng.nextInt(100);

    var largeIconPath = await _downloadAndSaveImage(
        'https://cdn.pixabay.com/photo/2019/04/21/21/29/pattern-4145023_960_720.jpg',
        'largeIcon');
    var bigPicturePath = await _downloadAndSaveImage(
        'https://cdn.pixabay.com/photo/2019/04/21/21/29/pattern-4145023_960_720.jpg',
        'bigPicture');
    var bigPictureStyleInformation = BigPictureStyleInformation(
        bigPicturePath, BitmapSource.FilePath,
        largeIcon: largeIconPath,
        largeIconBitmapSource: BitmapSource.FilePath,
        contentTitle: message['data']['title'],
        htmlFormatContentTitle: true,
        summaryText: message['data']['body'],
        htmlFormatSummaryText: true);
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        '12', 'trading_id', message['data']['body'],
        importance: Importance.High,
        priority: Priority.High,
        style: AndroidNotificationStyle.BigPicture,
        styleInformation: bigPictureStyleInformation);
    var platformChannelSpecifics =
        NotificationDetails(androidPlatformChannelSpecifics, null);
    await flutterLocalNotificationsPlugin.show(
        notifId,
        message['data']['title'],
        message['data']['body'],
        platformChannelSpecifics,
        payload: message['data']['body']);
  }

  Future<void> _showBigTextNotification(message) async {
    var rng = new Random();
    var notifId = rng.nextInt(100);
    var bigTextStyleInformation = BigTextStyleInformation(
        message['data']['body'],
        htmlFormatBigText: true,
        contentTitle: message['data']['title'],
        htmlFormatContentTitle: true,
        summaryText: message['data']['body'],
        htmlFormatSummaryText: true);
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        '12', 'trading_id', '',
        importance: Importance.High,
        priority: Priority.High,
        style: AndroidNotificationStyle.BigText,
        styleInformation: bigTextStyleInformation);
    var platformChannelSpecifics =
        NotificationDetails(androidPlatformChannelSpecifics, null);
    await flutterLocalNotificationsPlugin.show(
        notifId,
        message['data']['title'],
        message['data']['body'],
        platformChannelSpecifics,
        payload: message['data']['body']);
  }

  Future onSelectNotification(String payload) async {
    if (payload != null) {
      debugPrint('notification payload: ' + payload);
    }
    // await Navigator.push(
    //   context,
    //   new MaterialPageRoute(builder: (context) => new SecondScreen(payload)),
    // );
  }

  Future<void> onDidReceiveLocalNotification(
      int id, String title, String body, String payload) async {
    // display a dialog with the notification details, tap ok to go to another page
  }

  Future<String> _downloadAndSaveImage(String url, String fileName) async {
    var directory = await getApplicationDocumentsDirectory();
    var filePath = '${directory.path}/$fileName';
    var response = await http.get(url);
    var file = File(filePath);
    await file.writeAsBytes(response.bodyBytes);
    return filePath;
  }
}

我在主屏幕上这样称呼它

and i have called it like this in my home screen

   @override
  void initState() {
    // TODO: implement initState
    super.initState();
    new NotificationHandler().initializeFcmNotification();
  }

推荐答案

浏览了几个git线程和stackoverflow线程，终于找到了一个无人能说的最短答案:

After surfing for several git threads and stackoverflow threads, I finally found the shortest answer that no one could tell:

只需将处理程序放在全球范围内"

"JUST PUT THE HANDLERS IN GLOBAL SCOPE"

在您的whatever.dart 文件中，只需将_firebaseMessaging 和4 个处理程序、onMessage、onLaunch 等...放在本地类之外，瞧！没有崩溃！

in your whatever.dart file, just put the _firebaseMessaging and the 4 handlers, onMessage, onLaunch, etc... outside local class, and VOILA!! NO CRASH!

原文:

我使用 bkmza 回答，但不是跨平台的OP修复

I used bkmza answer , but was not OP fix for crossplatform

由于某种原因，设置

void initState() {
super.initState();
    _firebaseMessaging.configure
}

不工作，然后我尝试了

Future.delayed(Duration(seconds: 1), () {
     _firebaseMessaging.configure
    }
);

我让它完美地工作:)

也许 FCM 初始化尚未准备好配置处理程序，在 Firebase Core 完全加载后设置延迟使其正常工作

Maybe FCM initialisations was not ready to configure handlers, setting a delay after Firebase Core fully load made it work properly

这篇关于未处理的异常:NoSuchMethodError:方法 'toRawHandle' 在 null 上被调用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！