FCM -在Dart中无法处理背景消息，因为没有注册onBackgroundMessage处理程序。
FCM -在Dart中无法处理背景消息，因为没有注册onBackgroundMessage处理程序。
提问于 2022-02-04 15:59:39
我完全按照文档中提到的那样做了，这是main()之外的一个未来方法，其中的onBackgroundMessage
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async{
print("Handling a background message: ${message.messageId}");
}
main() async {
FirebaseMessaging.onBackgroundMessage((message){
return _firebaseMessagingBackgroundHandler(message);
});
}但是当我运行这个应用程序时，我会发现错误：
Unhandled Exception: Null check operator used on a null value
E/flutter (10760): #0 MethodChannelFirebaseMessaging.registerBackgroundMessageHandler (package:firebase_messaging_platform_interface/src/method_channel/method_channel_messaging.dart:180:53)
E/flutter (10760): #1 FirebaseMessagingPlatform.onBackgroundMessage= (package:firebase_messaging_platform_interface/src/platform_interface/platform_interface_messaging.dart:102:16)
E/flutter (10760): #2 FirebaseMessaging.onBackgroundMessage (package:firebase_messaging/src/messaging.dart:73:31)
E/flutter (10760): #3 main (package:neox/main.dart:56:21)
E/flutter (10760): #4 main (file:///E:/Flutter_Projects/NeoX/.dart_tool/flutter_build/generated_main.dart:102:42)
E/flutter (10760): #5 _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:128:38)
E/flutter (10760): #6 _rootRun (dart:async/zone.dart:1426:13)
E/flutter (10760): #7 _CustomZone.run (dart:async/zone.dart:1328:19)
E/flutter (10760): #8 _runZoned (dart:async/zone.dart:1861:10)
E/flutter (10760): #9 runZonedGuarded (dart:async/zone.dart:1849:12)
E/flutter (10760): #10 _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:126:5)
E/flutter (10760): #11 _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:297:19)
E/flutter (10760): #12 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)当我收到通知时：
W/FLTFireMsgService(10760): A background message could not be handled in Dart as no onBackgroundMessage handler has been registered.回答 2
Stack Overflow用户
发布于 2022-02-04 18:48:52
这是你需要的所有步骤
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
// you need to initialize firebase first
await Firebase.initializeApp();
print("Handling a background message: ${message.messageId}");
}
main() async {
WidgetsFlutterBinding.ensureInitialized();
// initialize firebase
await Firebase.initializeApp();
// you can just pass the function like this
FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
await FirebaseMessaging.instance.setForegroundNotificationPresentationOptions(
alert: true,
badge: true,
sound: true,
);
}Stack Overflow用户
发布于 2022-04-07 12:47:40
我想你是误读了文档
下面是在您的main.dart中应该如何使用
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
// If you're going to use other Firebase services in the background, such as Firestore,
// make sure you call `initializeApp` before using other Firebase services.
await Firebase.initializeApp();
print("Handling a background message: ${message.messageId}");
}
void main() {
FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);
runApp(MyApp());
}并记住配置您的AndroidManifest.xml
<service
android:name=".java.MyFirebaseMessagingService"
android:exported="false">
<intent-filter>
<action android:name="com.google.firebase.MESSAGING_EVENT" />
</intent-filter>
</service>当您面临此错误时：java.lang.RuntimeException:无法创建服务rw.aos.im.java.MyFirebaseMessagingService: java.lang.ClassNotFoundException：java.lang.RuntimeException
请使用以下方法
<service
android:name="com.google.firebase.messaging.FirebaseMessagingService"
android:exported="false">
<intent-filter>
<action android:name="com.google.firebase.MESSAGING_EVENT" />
</intent-filter>
</service>确保正确配置了下列所有设置
- https://firebase.google.com/docs/cloud-messaging/android/client
- https://firebase.google.com/docs/android/setup
希望这能解决你的问题
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/70989307
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