C# 通过代理获取url数据

 public static string doPost(string Url, byte[] postData, SinaCookie bCookie, String encodingFormat, String referer, string ProxyStr)
         {
                 try
                 {
                     HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(Url.ToString());
                     if (ProxyStr != ""&&ProxyStr != null)
                     {
                         //设置代理
                         WebProxy proxy = new WebProxy();
                         proxy.Address = new Uri(ProxyStr);
                         myRequest.UseDefaultCredentials = true;
                         myRequest.Proxy = proxy;
                     }
                     //myRequest.ServicePoint.Expect100Continue = false;
                     myRequest.CookieContainer = bCookie.mycookie;
                     myRequest.Method = "POST";
                     myRequest.Timeout = ;
                     myRequest.KeepAlive = true;//modify by yang
                     if (referer != "")
                         myRequest.Referer = referer;
                     myRequest.Headers["Cache-control"] = "no-cache";//.CachePolicy = .c "no-cache";//["Cache-control: no-cache"]
                     myRequest.Headers["Accept-Language"] = "zh-cn";
                     //myRequest.Headers["x-requested-with"] = "XMLHttpRequest";
                     myRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; Trident/4.0; GTB7.4; GTB7.1; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.2)";
                     myRequest.ContentType = "application/x-www-form-urlencoded";
                     myRequest.Accept = "*/*";
                     myRequest.ContentLength = postData.Length;

                     //setRequestHeader(requestHearder, myRequest);

                     Stream newStream = myRequest.GetRequestStream();
                     newStream.Write(postData, , postData.Length);
                     newStream.Close();
                     //if (waitTime != 0)
                     //    Thread.Sleep(waitTime);
                     HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();
                     bCookie.upcookie(myResponse.Cookies);
                     StreamReader reader = new StreamReader(myResponse.GetResponseStream(), Encoding.GetEncoding(encodingFormat));
                     string outdata = reader.ReadToEnd();
                     reader.Close();
                     if (!outdata.Contains("基础连接已经关闭: 连接被意外关闭") && !outdata.Contains("无法连接到远程服务器") && !outdata.Contains("基础连接已经关闭: 接收时发生错误。"))
                         return outdata;
                     else
                         return "基础连接已经关闭: 连接被意外关闭";

                 }
                 catch (Exception ex)
                 {
                     if (!ex.Message.Contains("基础连接已经关闭: 连接被意外关闭") && !ex.Message.Contains("无法连接到远程服务器") && !ex.Message.Contains("基础连接已经关闭: 接收时发生错误。"))
                         return ex.Message;
                     else
                         return "基础连接已经关闭: 连接被意外关闭";
                 }

         }

ProxyStr格式
http://192.168.1.1:80
大概是这样、