dart - 安装google api日历时出现flutter dart错误

Question

我将显示来自 Google 日历的事件列表。我已经按照以下链接中的示例进行操作:How to use Google API in flutter?

我的脚本如下:

将 'package:http/http.dart' 导入为 http;

假设我已经登录。

GoogleSignIn _googleSignIn = GoogleSignIn(
  scopes: <String>[
    'email',
    'https://www.googleapis.com/auth/contacts.readonly',
    'https://www.googleapis.com/auth/calendar'
  ],
);'

class GoogleHttpClient extends http.BaseClient {
  Map<String, String> _headers;

  GoogleHttpClient(this._headers) : super();

  @override
  Future<http.StreamedResponse> send(http.BaseRequest request) =>
      super.send(request..headers.addAll(_headers)); //have error 'the method 'send' is always abstract in the supertype'

  @override
  Future<http.Response> head(Object url, {Map<String, String> headers}) =>
      super.head(url, headers: headers..addAll(_headers));
}

void getCalendarEvents() async {
    final authHeaders = _googleSignIn.currentUser.authHeaders;
    final httpClient = new GoogleHttpClient(authHeaders); //have error "The argument type 'Future<Map<String, String>>' can't be assigned to the parameter type 'Map<String, String>'"
    var calendar = new Calendar.CalendarApi(new http.Client());
    var calEvents = calendar.events.list("primary");
    calEvents.then((Calendar.Events events) {
      events.items.forEach((Calendar.Event event) {print(event.summary);});
    });
}

由于错误，上述脚本无法运行。

the method 'send' is always abstract in the supertype

谁能帮帮我？

Answer 1

如果您的代码基于 How to use Google API in flutter?你会看到我有一个 @override Future<StreamedResponse> send(...)在我的代码中。

GoogleHttpClient延伸abstract class IOClient缺少 send 的实现，所以具体的子类需要实现它。

这就是错误消息的内容。