Silverlight - 尝试 POST 到 Web 服务时出现异常答案

【问题标题】：Silverlight - Exception when trying to POST to webserviceSilverlight - 尝试 POST 到 Web 服务时出现异常
【发布时间】：2011-09-20 21:18:51
【问题描述】：

我正在使用“发布”方法，因此我可以发送自定义对象。但我在 request.BeginGetResponse() 上不断收到以下异常：

{System.Net.ProtocolViolationException：由于对象的当前状态，操作无效。在 System.Net.Browser.BrowserHttpWebRequest.BeginGetResponseImplementation()}

public void Send()
    {
        HttpWebRequest client = WebRequest.Create(new Uri(BaseUrl)) as HttpWebRequest;
        client.Method = "POST";
        client.ContentLength = MaxSerializationSize;
        client.BeginGetRequestStream(new AsyncCallback(RequestProceed), client);
    }

    private void RequestProceed(IAsyncResult asuncResult)
    {
        HttpWebRequest request = (HttpWebRequest) asuncResult.AsyncState;

        StreamWriter postDataWriter = new StreamWriter(request.EndGetRequestStream(asuncResult));
        MemoryStream ms = new MemoryStream();
        DataContractJsonSerializer ser = new     DataContractJsonSerializer(typeof(MyCustomClass));
        ser.WriteObject(ms, MyCustomClassObject);
        postDataWriter.Write(ms);
        postDataWriter.Close();

        request.BeginGetResponse(new AsyncCallback(ResponceProceed), request);

    }

    private void ResponceProceed(IAsyncResult asuncResult)
    {
        var request = (HttpWebRequest) asuncResult.AsyncState;

        using (var resp = (HttpWebResponse) request.EndGetResponse(asuncResult))
        {
            using (var stream = resp.GetResponseStream())
            {
            }
        }
    }

我已经尝试了很多方法来让它发挥作用。希望有人能告诉我哪里出错了。谢谢。

【问题讨论】：

标签： silverlight wcf rest

【解决方案1】：

您需要关闭请求流。您只是关闭 StreamWriter 而不是底层请求流。当您使用它时，请消除多余的 MemoryStream 并让 DataContractJsonSerializer 直接写入请求流。

 HttpWebRequest request = (HttpWebRequest) asuncResult.AsyncState;

 using (Stream outStream = request.EndGetRequestStream(asyncResult));
 {
      DataContractJsonSerializer ser = new     DataContractJsonSerializer(typeof(MyCustomClass));           
      ser.WriteObject(outStream, MyCustomClassObject);
      outStream.Flush();
      outStream.Close();
 }

 request.BeginGetResponse(new AsyncCallback(ResponceProceed), request);

也去掉这行：-

 client.ContentLength = MaxSerializationSize;

如果不关闭AllowWriteStreamBuffering（无论如何只能在ClientHTTP 实现上实现），则无需设置ContentLength，这是为您完成的。

【讨论】：