ASP.NET POST方式提交数据

string url = "网址";
     HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
     string s = "要提交的数据";
     byte[] requestBytes = System.Text.Encoding.ASCII.GetBytes (LoginInfo);
     req.Method = "POST";
     req.ContentType = "application/x-www-form-urlencoded";
     req.ContentLength = requestBytes.Length;
     Stream requestStream = req.GetRequestStream();
     requestStream.Write(requestBytes,0,requestBytes.Length);
     requestStream.Close();

     HttpWebResponse res = (HttpWebResponse)req.GetResponse();
     StreamReader sr = new StreamReader(res.GetResponseStream(), System.Text.Encoding.Default);
     string backstr = sr.ReadToEnd();
     Response.Write(line);
     sr.Close();
     res.Close();