ASP.NET POST方式提交数据

protected void Page_Load(object sender, EventArgs e)
{
      if (!IsPostBack)
      {
      }
      else
      {
             if (Request["cmd"].Equals("1"))
             { 
                    //post解析地址
                    if (lon.Value.Trim().Length > 0 && lat.Value.Trim().Length > 0)
                    {
                        getaddress(lon.Value.Trim(), lat.Value.Trim());
                    }
             }
       }
}

private void getPostAddr(string lon, string lat)
{
        string url = "http://www.ciensharp.com/api/addreq";
        string postData = "postStr={" + string.Format("lon:{0},lat:{1},version:1.0.2", lon, lat) + "}&type=geocode";

        Encoding encoding = Encoding.UTF8;
        byte[] data = encoding.GetBytes(postData);

        //准备请求
        HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(url);
        myRequest.Method = "POST";
        myRequest.ContentType = "application/x-www-form-urlencoded";
        myRequest.ContentLength = data.Length;
        Stream stream = myRequest.GetRequestStream();

        //发送数据
        stream.Write(data, 0, data.Length);
        stream.Close();
  
        //获取数据
        HttpWebResponse res = (HttpWebResponse)myRequest.GetResponse();
        StreamReader sr = new StreamReader(res.GetResponseStream(), System.Text.Encoding.UTF8);
        string backstr = sr.ReadToEnd();
        Response.Write(backstr);
        sr.Close();
        res.Close();
}