令牌检索失败：SERVICE_NOT_AVAILABLE。将重试令牌检索

Question

void main() async{
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp(
  options: DefaultFirebaseOptions.currentPlatform
);
final _firebaseMessaing = FirebaseMessaging.instance;
await _firebaseMessaing.requestPermission();

final fCMToken = await _firebaseMessaing.getToken();
print("This is token =========> ${fCMToken}");

runApp(MyApp());
}

这里我想要令牌，但出现一些错误并且令牌不打印。不明白为什么我会遇到这个问题？

Unhandled Exception: [firebase_messaging/unknown] java.io.IOException: SERVICE_NOT_AVAILABLE

  E/flutter (17731): #0      StandardMethodCodec.decodeEnvelope 
(package:flutter/src/services/message_codecs.dart:651:7)
 E/flutter (17731): #1      MethodChannel._invokeMethod 
 (package:flutter/src/services/platform_channel.dart:322:18)
 E/flutter (17731): <asynchronous suspension>
 E/flutter (17731): #2      MethodChannel.invokeMapMethod 
 (package:flutter/src/services/platform_channel.dart:522:43)
 E/flutter (17731): <asynchronous suspension>
 E/flutter (17731): #3      MethodChannelFirebaseMessaging.getToken

Answer 1

你已经有了 _firebaseMessaing.RequestPermission()。该行请求用户的通知权限。在请求令牌之前确保此调用成功。您可以使用 _firebaseMessaing.GetNotificationSettings() 添加权限名测试并处理权限被拒绝的情况。