Ip获取请求ip

public class IPAdress
    {

        public static bool isIP(string str1)
        {
            if (str1 == null || str1 == string.Empty || str1.Length < 7 || str1.Length > 15) return false;
            string regformat = @"^\d{1,3}[\.]\d{1,3}[\.]\d{1,3}[\.]\d{1,3}$";
            Regex regex = new Regex(regformat, RegexOptions.IgnoreCase);
            return regex.IsMatch(str1);
        }

        /// <summary>
        /// 取得客户端真实IP。如果有代理则取第一个非内网地址
        /// </summary>
        public static string fetch()
        {

            string result = String.Empty;

            result = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
            if (result != null && result != String.Empty) {

                if (result.IndexOf(".") == -1)
                    result = null;
                else {
                    if (result.IndexOf(",") != -1) {

                        result = result.Replace(" ", "").Replace("'", "");
                        string[] temparyip = result.Split(",;".ToCharArray());
                        for (int i = 0; i < temparyip.Length; i++) {
                            if (isIP(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];
                            }
                        }
                    } else if (isIP(result))
                        return result;
                    else
                        result = null;
                }

            }

            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 (null == result || result == String.Empty)
                result = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

            if (result == null || result == String.Empty)
                result = HttpContext.Current.Request.UserHostAddress;

            return result;

        }

    }