C# Post提交数据

        /// <summary>
        /// Post提交数据
        /// </summary>
        /// <param name="postUrl">URL</param>
        /// <param name="paramData">参数</param>
        /// <returns></returns>
        private string PostWebRequest(string postUrl, string paramData)
        {
            string ret = string.Empty;
            try
            {
                if (!postUrl.StartsWith("http://"))
                    return "";

                byte[] byteArray = Encoding.Default.GetBytes(paramData); //转化
                HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(new Uri(postUrl));
                webReq.Method = "POST";
                webReq.ContentType = "application/x-www-form-urlencoded";

                webReq.ContentLength = byteArray.Length;
                Stream newStream = webReq.GetRequestStream();
                newStream.Write(byteArray, 0, byteArray.Length);//写入参数
                newStream.Close();
                HttpWebResponse response = (HttpWebResponse)webReq.GetResponse();
                StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                ret = sr.ReadToEnd();
                sr.Close();
                response.Close();
                newStream.Close();
            }
            catch (Exception ex)
            {
               return ex.Message;
            }
            return ret;
        }