获取客户端IP

#region public static string GetClientIP() 获取客户端的IP地址
        /// <summary>
        /// 获取客户端的IP地址
        /// </summary>
        /// <returns></returns>
        public static string GetClientIP()
        {
            string result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (!string.IsNullOrEmpty(result))
            {
                //可能有代理 
                if (result.IndexOf(".", StringComparison.Ordinal) == -1)
                    //没有"."肯定是非IPv4格式 
                    result = null;
                else
                {
                    if (result.IndexOf(",", StringComparison.Ordinal) != -1)
                    {
                        //有","，估计多个代理。取第一个不是内网的IP。 
                        result = result.Replace(" ", "").Replace("", "");
                        string[] temparyip = result.Split(",;".ToCharArray());
                        for (int i = 0; i < temparyip.Length; i++)
                        {
                            if (IsIPAddress(temparyip[i]) && temparyip[i].Substring(0, 3) != "10." && temparyip[i].Substring(0, 7) != "192.168" && temparyip[i].Substring(0, 7) != "172.16.")
                            {
                                return temparyip[i];//找到不是内网的地址 
                            }
                        }
                    }
                    else if (IsIPAddress(result)) //代理即是IP格式 
                        return result;
                    else
                        result = null;//代理中的内容 非IP，取IP 
                }
            }
            string ipAddress =
            (HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null &&
            HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != String.Empty) ? HttpContext.Current.Request.ServerVariables
            ["HTTP_X_FORWARDED_FOR"] : HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
            if (string.IsNullOrEmpty(result))
                result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
            if (string.IsNullOrEmpty(result))
                result = HttpContext.Current.Request.UserHostAddress;
            return result;
        }