Dart HttpOverrides用法及代码示例

此类有助于使用模拟实现覆盖HttpClient。它应该由客户端代码中的另一个类扩展，并具有构建模拟实现的覆盖。此基类中的实现默认为实际的HttpClient 实现。例如：

// An implementation of the HttpClient interface
class MyHttpClient implements HttpClient {
  MyHttpClient(SecurityContext? c);

  @override
  noSuchMethod(Invocation invocation) {
    // your implementation here
  }
}

void main() {
  HttpOverrides.runZoned(() {
    // Operations will use MyHttpClient instead of the real HttpClient
    // implementation whenever HttpClient is used.
  }, createHttpClient: (SecurityContext? c) => MyHttpClient(c));
}