为什么我在尝试使用HttpWebRequest时会收到ProtocolViolationException？

Question

我不知道.我正在尝试从我正在为Windows Phone构建的应用程序上的REST服务中获取XML.我总是在以下行获得例外:

HttpWebResponse response = request.EndGetResponse(ar) as HttpWebResponse;

我有以下设置(忽略坏网址,这只是一个例子..)

HttpWebRequest request = WebRequest.Create("https://domain.chargify.com/customers.xml") as HttpWebRequest;
NetworkCredential credentials = new NetworkCredential("appkeyhere", "password");
request.Credentials = credentials;
request.Method = "GET";
request.ContentType = "text/xml";
request.BeginGetResponse(new AsyncCallback(SomeCallback), request);
...
private void SomeCallback(IAsyncResult ar) {
    HttpWebRequest request = ar.AsyncState as HttpWebRequest;
    HttpWebResponse response = request.EndGetResponse(ar) as HttpWebResponse;
    StreamReader reader = new StreamReader(response.GetResponseStream());
    XElement xmlResult = XElement.Parse(reader.ReadToEnd());
    ...
}

例外情况如下:

System.Net.ProtocolViolationException was unhandled
Message=ProtocolViolationException
  StackTrace:
       at System.Net.Browser.ClientHttpWebRequest.PrepareAndSendRequest(String method, Uri requestUri, Stream requestBodyStream, WebHeaderCollection headerCollection, CookieContainer cookieContainer)
       at System.Net.Browser.ClientHttpWebRequest.BeginGetResponseImplementation()
       at System.Net.Browser.ClientHttpWebRequest.InternalBeginGetResponse(AsyncCallback callback, Object state)
       at System.Net.Browser.AsyncHelper.BeginOnUI(BeginMethod beginMethod, AsyncCallback callback, Object state)
       at System.Net.Browser.ClientHttpWebRequest.BeginGetResponse(AsyncCallback callback, Object state)
       at ChargifyWPA.MainPage.button1_Click(Object sender, RoutedEventArgs e)
       at System.Windows.Controls.Primitives.ButtonBase.OnClick()
       at System.Windows.Controls.Button.OnClick()
       at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
       at System.Windows.Controls.Control.OnMouseLeftButtonUp(Control ctrl, EventArgs e)
       at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr unmanagedObjArgs, Int32 argsTypeIndex, String eventName)

有人有主意吗？它是https,而不是http ..是导致问题的原因吗？谢谢.

Answer 1

这不是你的问题,但它可能对其他人有所帮助.我碰到了这个,因为我在GET请求上调用了BeginGetRequestStream().当然,这不是必要的,我应该刚刚调用BeginGetResponse().愚蠢的错误,但如果错误消息更有帮助,我会更快地想出来.

Answer 2

我打赌这个问题是因为您设置了'ContentType'标题,但没有在您的请求中提供内容.请注意,尝试创建请求时会抛出协议异常.

您可能需要将"Accept"标头设置为"text/xml"而不是内容类型标头.