错误：提交请求后无法执行此操作

Question

我编写了关于 httpwebrequest 和 httpwebresponse 的代码。我需要向服务器发送数据，但出现此异常“提交请求后无法执行此操作”。见以下代码：

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://"+remoteServer+":8080/");
request.Credentials = CredentialCache.DefaultCredentials;
//Stream NewReqstream = request.GetRequestStream();
request.Method = "POST";
//request.ContentLength = cmd.Length;
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Console.WriteLine("Connected..");

// Send the command
//clientSocket.Send(cmd);

Stream NewReqstream = request.GetRequestStream(); //<-- Error here
NewReqstream.Write(cmd, 0, cmd.Length);
NewReqstream.Close();

Answer 1

当你得到响应流时，请求被提交，所以你不能在那里操作......

试试看：

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://"+remoteServer+":8080/");
request.Credentials = CredentialCache.DefaultCredentials;
//Stream NewReqstream = request.GetRequestStream();
request.Method = "POST";
//request.ContentLength = cmd.Length;

// Send the command
//clientSocket.Send(cmd);

Stream NewReqstream = request.GetRequestStream(); //<-- Error here
NewReqstream.Write(cmd, 0, cmd.Length);
NewReqstream.Close();

// Get the response
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Console.WriteLine("Connected..");

Answer 2

异常告诉你你需要知道什么； HTTP 是请求 => 响应，因此，如果您要求响应 (GetResponse())，则您已隐含地说“我的请求已完成；给我响应”。将GetRequestStream() 代码移到上方 GetResponse()。