Firebase Cloud Messaging V1 API认证报错及迁移方案咨询

问题说明 #

猜测Firebase已对新用户禁用Legacy API，强制要求使用V1 API。使用Postman发送通知时收到如下401认证错误：

"error": {
        "code": 401,
        "message": "Request had invalid authentication credentials. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.",
        "status": "UNAUTHENTICATED"
    }

本人持有服务账号、Server Key等凭据，但不清楚如何完成API迁移。当前技术栈：dart-shelf作为后端，Flutter作为客户端，后端部署在Google Cloud Computing上。

Postman配置信息 #

• 授权设置：Authorization = Bearer +AAAAA..token
• 请求体内容：

{
  "message":{
     "token":"<generated token by flutter>",
     "notification":{
       "body":"This is an FCM notification message!",
       "title":"FCM Message"
     }
  }
}

Flutter端生成设备Token的代码 #

@override
void initState() {
  super.initState();
  WidgetsBinding.instance.addPostFrameCallback((timeStamp) async {
    _init();
  });
  var initializationSettingsAndroid =
      const AndroidInitializationSettings('ic_launcher');
  var initialzationSettingsAndroid =
      const AndroidInitializationSettings('@mipmap/ic_launcher');
  var initializationSettings =
      InitializationSettings(android: initialzationSettingsAndroid);
  flutterLocalNotificationsPlugin.initialize(initializationSettings);

  FirebaseMessaging.onMessage.listen((RemoteMessage message) {
    RemoteNotification? notification = message.notification;
    AndroidNotification? android = message.notification?.android;
    if (notification != null && android != null) {
      flutterLocalNotificationsPlugin.show(
          notification.hashCode,
          notification.title,
          notification.body,
          NotificationDetails(
            android: AndroidNotificationDetails(
              channel.id,
              channel.name,
              color: Colors.blue,
              // TODO add a proper drawable resource to android, for now using
              //      one that already exists in example app.
              icon: "@mipmap/ic_launcher",
            ),
          ));
    }
  });

  FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
    RemoteNotification? notification = message.notification;
    AndroidNotification? android = message.notification?.android;
    if (notification != null && android != null) {
      showDialog(
          context: context,
          builder: (_) {
            return AlertDialog(
              title: Text(notification.title!),
              content: SingleChildScrollView(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [Text(notification.body!)],
                ),
              ),
            );
          });
    }
  });

  getToken();
}

内容的提问来源于stack exchange，提问作者demonjoseph