c# - System.Net.ProtocolViolationException异常C#发布和获取响应

对于以下代码，我得到以下错误，


  System.Net.ProtocolViolationException：您必须提供一个请求正文
  如果您设置ContentLength> 0或SendChunked == true。通过致电做到这一点
  [Begin] GetResponse之前的[Begin] GetRequestStream。


我不确定为什么会引发此错误，任何评论或建议都将有所帮助

                 HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://");

                 // Set the ContentType property.
                 request.ContentType = "application/x-www-form-urlencoded";
                 // Set the Method property to 'POST' to post data to the URI.
                 request.Method = "POST";
                 request.KeepAlive = true;
                 byte[] byteArray = Encoding.UTF8.GetBytes(postData);
                 request.ContentLength = byteArray.Length;
                 // Start the asynchronous operation.
                 request.BeginGetRequestStream(new AsyncCallback(ReadCallback), request);

                 // Keep the main thread from continuing while the asynchronous
                 // operation completes. A real world application
                 // could do something useful such as updating its user interface.
                 allDone.WaitOne();

                 // Get the response.
                 HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                 Stream streamResponse = response.GetResponseStream();
                 StreamReader streamRead = new StreamReader(streamResponse);
                 string responseString = streamRead.ReadToEnd();
                 Console.WriteLine(responseString);
                 Console.ReadLine();
                 // Close the stream object.
                 streamResponse.Close();
                 streamRead.Close();

                 // Release the HttpWebResponse.
                 response.Close();





    private static void ReadCallback(IAsyncResult asynchronousResult)
    {

        HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;

        // End the operation.
        Stream postStream = request.EndGetRequestStream(asynchronousResult);



        // Convert the string into a byte array.
        byte[] byteArray = Encoding.UTF8.GetBytes(postData);

        // Write to the request stream.
        postStream.Write(byteArray, 0, postData.Length);
        postStream.Close();
        allDone.Set();
    }

现在，我修改了使用HttpClient的代码，但无法正常工作，

    public static async void PostAsync(String postData)
    {

        try
        {
            // Create a New HttpClient object.
            HttpClient client = new HttpClient();

            HttpResponseMessage response = await client.PostAsync("http://", new StringContent(postData));
            Console.WriteLine(response);
            //response.EnsureSuccessStatusCode();
            string responseBody = await response.Content.ReadAsStringAsync();
            // Above three lines can be replaced with new helper method in following line
            // string body = await client.GetStringAsync(uri);

            Console.WriteLine(responseBody);

        }
        catch (HttpRequestException e)
        {
            Console.WriteLine("\nException Caught!");
            Console.WriteLine("Message :{0} ", e.Message);

        }
    }

最佳答案

该错误很可能是由于您混合了异步操作和同步操作而导致的。 HttpWebRequest.BeginGetRequestStream的文档说：


  您的应用程序不能为特定请求混合同步和异步方法。如果调用BeginGetRequestStream方法，则必须使用BeginGetResponse方法来检索响应。


您的代码调用BeginGetRequestStream，但是调用GetResponse。

我认为正在发生的事情是它调用了BeginGetRequestStream，这开始异步写入请求流，但是在主线程上它同时调用了GetResponse。因此，它正在尝试在格式化请求之前发出请求。

研究链接的MSDN主题中的示例，并相应地修改您的代码。

关于c# - System.Net.ProtocolViolationException异常C#发布和获取响应，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/18192423/