Firebase 颤振-FCM由于未注册onBackgroundMessage处理程序，因此无法在Dart中处理背景消息

我想在颤振中处理FCM的背景消息，但当FCM在后台模式下向应用程序发送消息时出错，并在日志中出错

pubspec.yaml:

firebase_core: ^0.7.0
firebase_messaging: ^8.0.0-dev.14

MainActivity.kt：

package com.mydomain.myproject

import io.flutter.embedding.android.FlutterActivity

class MainActivity: FlutterActivity() {
}

package com.mydomain.myproject

import com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin
import io.flutter.app.FlutterApplication
import io.flutter.plugin.common.PluginRegistry
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingBackgroundExecutor
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingBackgroundService
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingPlugin
import io.flutter.plugins.pathprovider.PathProviderPlugin


class MyApplication : FlutterApplication(), PluginRegistrantCallback {

    override
    fun onCreate() {
        super.onCreate()
        FlutterFirebaseMessagingBackgroundService.setPluginRegistrant(this)
        FlutterFirebaseMessagingBackgroundExecutor.setPluginRegistrant(this)
    }

    override
    fun registerWith(registry: PluginRegistry) {
        PathProviderPlugin.registerWith(registry.registrarFor("io.flutter.plugins.pathprovider.PathProviderPlugin"))
        FlutterLocalNotificationsPlugin.registerWith(registry.registrarFor("com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin"))
        FlutterFirebaseMessagingPlugin.registerWith(registry.registrarFor("plugins.flutter.io/firebase_messaging"))
    }
}

应用程序.kt：

package com.mydomain.myproject

import io.flutter.embedding.android.FlutterActivity

class MainActivity: FlutterActivity() {
}

package com.mydomain.myproject

import com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin
import io.flutter.app.FlutterApplication
import io.flutter.plugin.common.PluginRegistry
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingBackgroundExecutor
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingBackgroundService
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingPlugin
import io.flutter.plugins.pathprovider.PathProviderPlugin


class MyApplication : FlutterApplication(), PluginRegistrantCallback {

    override
    fun onCreate() {
        super.onCreate()
        FlutterFirebaseMessagingBackgroundService.setPluginRegistrant(this)
        FlutterFirebaseMessagingBackgroundExecutor.setPluginRegistrant(this)
    }

    override
    fun registerWith(registry: PluginRegistry) {
        PathProviderPlugin.registerWith(registry.registrarFor("io.flutter.plugins.pathprovider.PathProviderPlugin"))
        FlutterLocalNotificationsPlugin.registerWith(registry.registrarFor("com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin"))
        FlutterFirebaseMessagingPlugin.registerWith(registry.registrarFor("plugins.flutter.io/firebase_messaging"))
    }
}

使用fcm的代码： 我刚刚在主应用程序类的initState（）中调用了_initFcm（）。 我的目标是当应用程序在后台时，后台fcm方法必须触发，并且我必须将消息数据保存在prefrence中，以便在应用程序打开时对其进行处理

void _initFcm() {
    Firebase.initializeApp();
    FirebaseMessaging.onMessageOpenedApp.listen((message) {
      Logger.log("_messaging onMessageOpenedApp: ${message}");
    });
    FirebaseMessaging.instance.getInitialMessage().then((value) {
      Logger.log("_messaging getInitialMessage: ${value}");
    });
    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      RemoteNotification notification = message.notification;
      Map<String, dynamic> data = message.data;
      Logger.log("_messaging onMessage: ${message}");
      Fcm.showNotification(notification.body, notification.title);
      String type = data['type'];
      if (type == "view") {
        String notifPath = data['subject'];
        notificationProvider.addPath(notifPath);
        Logger.log('new notification added to notificationList: ${notifPath}');
      }
    });
    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      Logger.log("_messaging onMessageOpenedApp: $message");
    });
    FirebaseMessaging.onBackgroundMessage((message) {
      Logger.log("_messaging onBackgroundMessage: $message");
      return;
    });
  }

void\u initFcm（）{
Firebase.initializeApp（）；
FirebaseMessaging.onMessageGeoPenedApp.listen（（消息）{
Logger.log（“_messagingonmessagegeopenedapp:${message}”）；
});
FirebaseMessaging.instance.getInitialMessage（）.then（（值）{
Logger.log（“_messaginggetInitialMessage:${value}”）；
});
FireBaseMessage.onMessage.listen（（远程消息）{
RemoteNotification通知=message.notification；
地图数据=message.data；
Logger.log（“\u messaging onMessage:${message}”）；
Fcm.showNotification（notification.body，notification.title）；
字符串类型=数据['type']；
如果（类型=“视图”）{
字符串notifPath=data['subject']；
notificationProvider.addPath（notifPath）；
Logger.log（'新通知添加到notificationList:${notifPath}'）；
}
});
FirebaseMessaging.onMessageGeoPenedApp.listen（（远程消息）{
Logger.log（“_messagingonmessagegeopenedapp:$message”）；
});
FirebaseMessaging.onBackgroundMessage（（消息）{
Logger.log（“\u messaging onBackgroundMessage:$message”）；
返回；
});
}

运行日志：

[ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: NoSuchMethodError: The method 'toRawHandle' was called on null.
E/flutter ( 5030): Receiver: null
E/flutter ( 5030): Tried calling: toRawHandle()
E/flutter ( 5030): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
E/flutter ( 5030): #1      MethodChannelFirebaseMessaging.registerBackgroundMessageHandler (package:firebase_messaging_platform_interface/src/method_channel/method_channel_messaging.dart:181:42)
E/flutter ( 5030): #2      FirebaseMessagingPlatform.onBackgroundMessage= (package:firebase_messaging_platform_interface/src/platform_interface/platform_interface_messaging.dart:107:14)
E/flutter ( 5030): #3      FirebaseMessaging.onBackgroundMessage (package:firebase_messaging/src/messaging.dart:103:31)
E/flutter ( 5030): #4      _ChatrAppState._initFcm (package:parsian_chatr/app/ui/chatr_app.dart:90:23)
E/flutter ( 5030): #5      _ChatrAppState.initState (package:parsian_chatr/app/ui/chatr_app.dart:69:5)
E/flutter ( 5030): #6      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4765:58)
E/flutter ( 5030): #7      ComponentElement.mount (package:flutter/src/widgets/framework.dart:4601:5)
E/flutter ( 5030): #8      Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
E/flutter ( 5030): #9      Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
E/flutter ( 5030): #10     RenderObjectToWidgetElement._rebuild (package:flutter/src/widgets/binding.dart:1252:16)
E/flutter ( 5030): #11     RenderObjectToWidgetElement.mount (package:flutter/src/widgets/binding.dart:1223:5)
E/flutter ( 5030): #12     RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure> (package:flutter/src/widgets/binding.dart:1165:17)
E/flutter ( 5030): #13     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2683:19)
E/flutter ( 5030): #14     RenderObjectToWidgetAdapter.attachToRenderTree (package:flutter/src/widgets/binding.dart:1164:13)
E/flutter ( 5030): #15     WidgetsBinding.attachRootWidget (package:flutter/src/widgets/binding.dart:974:7)
E/flutter ( 5030): #16     WidgetsBinding.scheduleAttachRootWidget.<anonymous closure> (package:flutter/src/widgets/binding.dart:955:7)
E/flutter ( 5030): #17     _rootRun (dart:async/zone.dart:1182:47)
E/flutter ( 5030): #18     _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 5030): #19     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter ( 5030): #20     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
E/flutter ( 5030): #21     _rootRun (dart:async/zone.dart:1190:13)
E/flutter ( 5030): #22     _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 5030): #23     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:1021:23)
E/flutter ( 5030): #24     Timer._createTimer.<anonymous closure> (dart:async-patch/timer_patch.dart:18:15)
E/flutter ( 5030): #25     _Timer._runTimers (dart:isolate-patch/timer_impl.dart:397:19)
E/flutter ( 5030): #26     _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:428:5)
E/flutter ( 5030): #27     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)
E/flutter ( 5030): 

[错误：flatter/lib/ui/ui\u dart\u state.cc（177）]未处理的异常：NoSuchMethodError:对null调用了方法“toRawHandle”。
E/颤振（5030）：接收器：空
E/flatter（5030）：尝试调用：toRawHandle（）
E/颤振（5030）：#0 Object.noSuchMethod（dart:core patch/Object_patch.dart:51:5）
E/Flatter（5030）：#1 MethodChannelFirebaseMessaging.registerBackgroundMessageHandler（包：firebase_messaging_平台_interface/src/method_channel/method_channel_messaging.dart:181:42）
E/flatter（5030）：#2 FirebaseMessagingPlatform.onBackgroundMessage=（包：firebase_消息传递_平台_接口/src/platform_接口/平台_接口_消息传递。dart:107:14）
E/flatter（5030）：#3 FirebaseMessaging.onBackgroundMessage（包：firebase_messaging/src/messaging.dart:103:31）
电子/颤振（5030）：#4(聊天室状态.)初始FCM（软件包：parsian(聊天室/应用程序/用户界面/聊天室)应用程序dart:90:23）
E/flatter（5030）：#5 40; ChatrAppState.initState)（包：parsian_chatr/app/ui/chatr_app.dart:69:5）
E/flatter（5030）：#6 StatefulElement._firstBuild（包：flatter/src/widgets/framework.dart:4765:58）
E/flatter（5030）：#7 ComponentElement.mount（包：flatter/src/widgets/framework.dart:4601:5）
E/flatter（5030）：#8 Element.inflateWidget（包：flatter/src/widgets/framework.dart:3569:14）
E/flatter（5030）：#9 Element.updateChild（包：flatter/src/widgets/framework.dart:3327:18）
E/flatter（5030）：#10 RenderObjectToWidgetElement._重建（包：flatter/src/widgets/binding.dart:1252:16）
E/flatter（5030）：#11 RenderObjectToWidgetElement.mount（包：flatter/src/widgets/binding.dart:1223:5）
E/颤振（5030）：#12渲染对象到WidgetAdapter.attachToRenderTree。（包：flatter/src/widgets/binding.dart:1165:17）
E/flatter（5030）：#13 BuildOwner.buildScope（包：flatter/src/widgets/framework.dart:2683:19）
E/flatter（5030）：#14 RenderObjectToWidgetAdapter.attachToRenderTree（包：flatter/src/widgets/binding.dart:1164:13）
E/flatter（5030）：#15 WidgetsBinding.attachRootWidget（包：flatter/src/widgets/binding.dart:974:7）
E/颤振（5030）：#16 widgetsbind.scheduleAttachRootWidget。（包：flatter/src/widgets/binding.dart:955:7）
E/flatter（5030）：#17_rootRun（dart:async/zone.dart:1182:47）
E/flatter（5030）：#18 _CustomZone.run（dart:async/zone.dart:1093:19）
E/flatter（5030）：#19 _CustomZone.runguard（dart:async/zone.dart:997:7）
E/颤振（5030）：#20_CustomZone.bindCallbackguared。（dart:async/zone.dart:1037:23）
E/flatter（5030）：#21 rootRun（dart:async/zone.dart:1190:13）
E/flatter（5030）：#22 _CustomZone.run（dart:async/zone.dart:1093:19）
E/颤振（5030）：#23 _CustomZone.bindCallback。（dart:async/zone.dart:1021:23）
E/颤振（5030）：24定时器。（dart:async patch/timer_patch.dart:18:15）
E/颤振（5030）：#25 _计时器。_运行计时器（dart:isolate patch/Timer_impl.dart:397:19）
E/颤振（5030）：#26 _定时器。_handleMessage（省道：隔离补丁/定时器_impl.省道：428:5）
E/颤振（5030）：#27(RawReceivePortImpl.)处理消息（dart:隔离补丁/隔离补丁。dart:168:12）
E/颤振（5030）：

试试这个

在包含MainApp类的文件中添加处理程序。记得把它添加到课堂之外

Future<void> firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  print("Handling a background message");
}

与

参考：

关于你的背景信息，有几件事需要记住 处理程序：

它不能是匿名函数。它必须是顶级函数 （例如，不是需要初始化的类方法）

---

在您的代码中被调用了两次

您能添加一些代码吗？在

catr\U应用程序中添加代码。dart

肯定会有助于理解可能出现的问题。@dm\u tr是的，添加了代码，我编辑了问题请检查是否确实编辑了问题？升级到firebase后，我可以在我的应用程序中确认相同的问题。\ u消息：^8.0.0-dev.14

FirebaseMessaging.onMessageOpenedApp.listen((message) {
  Logger.log("_messaging onMessageOpenedApp: ${message}");
});