flutter开启http服务，可用于投屏，或者对外提供接口

var _httpServer = await HttpServer.bind(
  InternetAddress.anyIPv4,
  8081,
  shared: true,
);

_httpServer!.listen(
  (HttpRequest request) async {
    File file = File(pathUrl);
    await request.response.addStream(file.openRead());
    request.response.close();
  },
  onError: (e) {},
  onDone: () {},
  cancelOnError: true,
);