【ASP.NET 进阶】根据IP地址返回对应位置信息

        /// <summary>获取客户端IP地址（无视代理）</summary>
        /// <returns>若失败则返回回送地址</returns>
        public static string GetHostAddress()
        {
            string userHostAddress = HttpContext.Current.Request.UserHostAddress;

            if (string.IsNullOrEmpty(userHostAddress))
            {
                userHostAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
            }

            //最后判断获取是否成功，并检查IP地址的格式（检查其格式非常重要）
            if (!string.IsNullOrEmpty(userHostAddress) && IsIP(userHostAddress))
            {
                return userHostAddress;
            }
            return "127.0.0.1";
        }

        /// <summary>
        /// 检查IP地址格式
        /// </summary>
        /// <param name="ip"></param>
        /// <returns></returns>
        public static bool IsIP(string ip)
        {
            return System.Text.RegularExpressions.Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");
        

        private const string THE_KEY = "***************"; //你的AK密钥
        /// <summary>返回UTF-8编码服务地址</summary>
        /// <returns>服务地址</returns>
        public string GetPostUrl(string theIP)
        {
            string postUrl = "http://api.map.baidu.com/location/ip?ak=" + THE_KEY + "&ip=" + theIP + "&coor=bd09ll";
            return postUrl;
        }

        /// <summary> 返回结果（地址解析的结果） </summary>
        public static string GetInfoByUrl(string url)
        {
            //调用时只需要把拼成的URL传给该函数即可。判断返回值即可
            string strRet = null;

            if (url == null || url.Trim().ToString() == "")
            {
                return strRet;
            }
            string targeturl = url.Trim().ToString();
            try
            {
                HttpWebRequest hr = (HttpWebRequest)WebRequest.Create(targeturl);
                hr.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)";
                hr.Method = "GET";
                hr.Timeout = 30 * 60 * 1000;
                WebResponse hs = hr.GetResponse();
                Stream sr = hs.GetResponseStream();
                StreamReader ser = new StreamReader(sr, Encoding.Default);
                strRet = ser.ReadToEnd();
            }
            catch (Exception ex)
            {
                strRet = null;
            }
            return strRet;
        }

                string theIP = YMethod.GetHostAddress();
                string msg = YMethod.GetInfoByUrl(GetPostUrl(theIP));
                msg = System.Text.RegularExpressions.Regex.Unescape(msg);
                Response.Write(msg);