webDav列表出文件夾內容的時候，當需要代理時使用WebRequest 代替XMLHTTP30

System.Uri myURi = new System.Uri(remoteHost + dirname);

                WebRequest req = WebRequest.Create(myURi);
                req.Method = "PROPFIND";

                req.Credentials = new NetworkCredential(user, password);//用户名,密码
                req.Proxy = WebRequest.DefaultWebProxy;   //使用默認IE代理
                req.PreAuthenticate = true;
                req.ContentType = "text/xml";
                req.Headers.Add("Depth", "1,noroot");
                Stream resStream = req.GetRequestStream();

                string strXml;
                strXml = "<?xml version=/"1.0/"?> ";
                strXml += "<d:propfind xmlns:d=/"DAV:/">";
                strXml += "<d:prop>";
                strXml += "<d:iscollection/>";
                strXml += "<d:getcontentlength/>";
                strXml += "<d:getlastmodified/>";
                strXml += "<d:displayname/>";
                strXml += "</d:prop>";
                strXml += "</d:propfind>";

                byte[] reqXml = Encoding.Default.GetBytes(strXml);
                resStream.Write(reqXml, 0, reqXml.Length);
                resStream.Flush();
                resStream.Close();
                WebResponse res = req.GetResponse();
                Stream responseStream = res.GetResponseStream();