/// <summary>
        /// 取客户端IP函数
        /// </summary>
        /// <returns>取客户端IP函数</returns>
        public static string GetClientIP()
        {
            string m_sClientIP = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (m_sClientIP == null || m_sClientIP == String.Empty)
            {
                m_sClientIP = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
            }

            if (m_sClientIP == null || m_sClientIP == String.Empty)
            {
                m_sClientIP = HttpContext.Current.Request.UserHostAddress;
            }
            return m_sClientIP;
        }

------解决方案--------------------

string ip = Request.ServerVariables["REMOTE_ADDR"].ToString();

------解决方案--------------------
为什么不用封装好的，还有智能提示的Request.UserHostAddress