asp.net 通过获取IP地址 查询地理位置解决方案

asp.net 通过获取IP地址 查询地理位置
帮忙详细解释这段代码的意思 

C# code

private string m_Location = "", m_IpAddress = "", m_Response = "";        /// <summary>        /// 新建IpLocation实例以获得IP地理位置        /// </summary>        /// <param name="ipAddress"></param>        public IpLocation(string ipAddress)        {            m_IpAddress = ipAddress.Trim();            string[] ip = ipAddress.Split('.');            ipAddress = ip[0] + "." + ip[1] + ".1.1";            WebClient client = new WebClient();            client.Encoding = System.Text.Encoding.GetEncoding("GB2312");            string url = "http://www.ip138.com/ips.asp";            string post = "ip=" + ipAddress + "&action=2";            client.Headers.Set("Content-Type", "application/x-www-form-urlencoded");         //尤其是这一句            string response = client.UploadString(url, post);                                 //这里            m_Response = response;                                                                           string p = @"<li>参考数据二：(?<location>[^<>]+?)</li>";                         //和这一句            Match match = Regex.Match(response, p);                                           //还有这里            m_Location = match.Groups["location"].Value.Trim();                                 //和这里        }        /// <summary>        /// 返回Ip地址的地理位置名称        /// </summary>        public string Location        {            get            {                return m_Location;            }        }        public string IpAddress        {            get            {                return m_IpAddress;            }        }        /// <summary>        /// 返回网络反馈原始数据        /// </summary>        public string Response        {            get            {                return m_Response;            }        }

C# code

// 指定表单向服务器提交的编码类型,默认就上这个            client.Headers.Set("Content-Type", "application/x-www-form-urlencoded");         //尤其是这一句            // 向"http://www.ip138.com/ips.asp";页面post数据            string response = client.UploadString(url, post);                                 //这里            m_Response = response;            // 用于解析结果的正则表达式            string p = @"<li>参考数据二：(?<location>[^<>]+?)</li>";                         //和这一句            // 正则解析网页的返回内容            Match match = Regex.Match(response, p);                                           //还有这里                        // 取出匹配内容            m_Location = match.Groups["location"].Value.Trim();                                 //和这里