获取客户端IP主机地址。

 /// 

        /// 获取客户端IP主机地址。
        /// 
        /// 
        public static string GetIP()
        {
            HttpRequest request = HttpContext.Current.Request;
            string result = request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (string.IsNullOrEmpty(result))
            {
                result = request.ServerVariables["REMOTE_ADDR"];
            }
            if (string.IsNullOrEmpty(result))
            {
                result = request.UserHostAddress;
            }
            //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）
            string patten = @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$";
            if (!string.IsNullOrEmpty(result) && Regex.IsMatch(result, patten))
            {
                return result;
            }

            return "127.0.0.1";
        }