asp.net 获取返回的xml数据中的值解决方法

 Encoding utf8 = Encoding.UTF8;
        Encoding gbk = Encoding.GetEncoding("gbk");
        
        byte[] tmp = utf8.GetBytes(URL);
    
        byte[] tmp1 = Encoding.Convert(utf8, gbk, tmp);
        
        string result = gbk.GetString(tmp1);
      
        byte[] buffer = Encoding.UTF8.GetBytes(result);
        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(URL);
        ////做请求
        req.Method = "POST";
        req.ContentType = "application/x-www-form-urlencoded";
        req.ContentLength = buffer.Length;
        Stream reqst = req.GetRequestStream();
        reqst.Write(buffer, 0, buffer.Length);
        reqst.Flush();
        reqst.Close();       
        HttpWebResponse res = (HttpWebResponse)req.GetResponse();
        //读结果
        Stream resst = res.GetResponseStream();
        StreamReader sr = new StreamReader(resst);        
        XmlDocument rssDoc = new XmlDocument();
        rssDoc.Load(resst);
        XmlNode rss = rssDoc.SelectSingleNode("result/response");        
        string DHResult = rss.Attributes[0].Value.ToString();
        resst.Close();
        sr.Close();

        return DHResult;