c#模拟http post请求

前段时间写快递查询，用的是快递鸟的接口，需要后台模拟post请求，现将代码上传如下：

 try
            {
                var postDataStr = "EBusinessID=" + EBusinessID + "&RequestData=" + RequestData + "&RequestType=" + RequestType + "&DataSign=" + DataSign + "&DataType=" + DataType + "";
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = Encoding.UTF8.GetByteCount(postDataStr);
                //request.CookieContainer = cookie;
                Stream myRequestStream = request.GetRequestStream();
                StreamWriter myStreamWriter = new StreamWriter(myRequestStream, Encoding.GetEncoding("gb2312"));
                myStreamWriter.Write(postDataStr);
                myStreamWriter.Close();
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();

                Stream myResponseStream = response.GetResponseStream();
                StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
                string retString = myStreamReader.ReadToEnd();
                myStreamReader.Close();
                myResponseStream.Close();

                return retString;
            }
            catch
            {
                return "查询失败";
            }

不喜勿喷，只是自己做的笔记。