百度api如何主动推送sitemap(C#+asp.net)

#region PostBaidu
        /*
        ///http://data.zz.baidu.com/urls?site=www.cha600.com&token=-----

       //说明：此方法适合百度站长，利用此方法可以第一时间将你的原创文章上传到百度，保护你的著作权，也可以帮你的网站进行引流
        User-Agent: curl/7.12.1
        Host: data.zz.baidu.com
        Content-Type: text/plain
        Content-Length: 83
         //以下是代码实现：
         * */
      ///
        /// 提交文章链接到百度
        ///
        ///文章的链接
        ///是否为原创
       public static string  PostBaidu(string url,string host,string token, bool IsOriginal,string encodingstr)
        {
            string retString = "";
            string Stie = host;
            string Token = token;
            string urlPage = "http://data.zz.baidu.com/urls?site=" + Stie + "&token=" + Token + "";
            if (IsOriginal)
            {
                urlPage += "&type=original";
            }            
            HttpWebRequest request = null;
            string body = url;
            if (url.Contains(".txt"))
            {
                body = FilePro.ReadText(url, encodingstr);  //如果不是链接是文本，直接读取文本内容 url为物理路径
            }
            Encoding encoding = Encoding.GetEncoding(encodingstr);
            byte[] data = encoding.GetBytes(body);               //这里采用GBK编码
 
            //设置提交的参数         
            request = WebRequest.Create(urlPage) as HttpWebRequest;
            request.Method = "POST";
            request.UserAgent = "curl/7.12.1";
            request.ContentType = "text/plain";
            request.ContentLength = data.Length;
            using (Stream requestStream = request.GetRequestStream())
            {
                requestStream.Write(data, 0, data.Length);
                requestStream.Flush();
                requestStream.Close();
            } 
            //测试返回结果 
            HttpWebResponse response;
            try
            {
                 response = (HttpWebResponse)request.GetResponse();
                
            }
            catch (WebException ex)
            {
                response = (HttpWebResponse)ex.Response;
            }
            Stream myResponseStream = response.GetResponseStream();
            StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
            retString = myStreamReader.ReadToEnd();
            return retString;
       }    
      #endregion


//调用

if (useridfrom == userreg2.Userid)
            {

                //开始主动推送api
                string host = userreg2.Shophost;
                string token = "AJ9l*****";
                string url = userreg2.Shophost + "_sitemap.txt";
                if (url.Contains(".txt"))
                {
                    url = Server.MapPath(Fun.Webdirectory + url);
                }
                bool IsOriginal = false;
                string encodingstr = "GB2312";
                string res = HttpService.PostBaidu(url, host, token, IsOriginal, encodingstr);
                Response.Write(res);
            }
            else
            {
                Response.Write("请登录店铺后台操作！");
            }
            return new EmptyResult();