Question

我如下图所示设置了镖服务器。我可以从Flutter Mobile应用发送数据，也可以从Dart Server接收数据。

如果请求方法是dart Server中的GET，我将连接到tcp套接字并获取一些数据。我需要发送到Flutter应用程序的数据必须为JSON格式。

我尝试将request.response.headers.contentType设置为json，但我不断收到错误消息HttpException：HTTP标头不可更改。

代码部分：

var _secureResponse = {};
_secureResponse[“Data”] = "$_returningServerData";
_secureResult = json.encode(_secureResponse);

request.response.headers.contentType = new ContentType("application", "json", charset: "utf-8");
request.response.write(_secureResult);
request.response.close();

错误：

空
未处理的异常：HttpException：HTTP标头不可更改
HttpHeaders._checkMutable（dart：_http / http_headers.dart：447：20）
HttpHeaders.contentType =（dart：_http / http_headers.dart：267：5）

服务器代码：

Future main() async {
  final HttpServer server = await HttpServer.bind("127.0.0.1", 8080);
  server.listen((HttpRequest request) async {

    print(request.headers.contentType);

    try {
      if (request.method == "GET") {
         String _requestData = ......
          Socket _socket = await Socket.connect('192.168.22.129', 3000);

          // READ FROM CSERVER
          _socket.listen((List<int> event) {
            _reply = new String.fromCharCodes(event).trim();
          });

          // WRITE TO SERVER
          _socket.add(utf8.encode('$_requestData\r\n'));

          // wait 1 seconds
          await Future.delayed(Duration(milliseconds: 1000));
          _socket.close();

          var _secureResponse = {};
          _secureResponse["Data"] = "$_reply";
          _secureResult = json.encode(_secureResponse);

          request.response.headers.contentType = new    
          ContentType("application", "json", charset: "utf-8");
          request.response.write(_secureResult);
          request.response.close();

        }

    } finally {
      var _secureResponse = {};
      _secureResponse["Data"] = "ERROR";
      _secureResult = json.encode(_secureResponse);

      request.response.headers.contentType = new 
      ContentType("application", "json", charset: "utf-8");
      request.response.write(_secureResult);
      request.response.close();
    }
  });
}

Answer 1

请参见https://api.dartlang.org/stable/2.1.0/dart-io/HttpHeaders-class.html

您尝试过类似的事情

request.headers.set(HttpHeaders.cacheControlHeader,
                    'max-age=3600, must-revalidate');

如果您要在Dart中构建服务器，我是否建议您使用package:shelf-更加用户友好。

如何在Dart Server中设置request.response的内容类型？

1 个答案: