/// <summary>
        /// 验证IP地址是否合法
        /// </summary>
        /// <param name="ip">要验证的IP地址</param>        
        public static bool IsIP(string ip)
        {
            //如果为空，认为验证合格
            if (IsNullOrEmpty(ip))
            {
                return true;
            }

            //清除要验证字符串中的空格
            ip = ip.Trim();

            //模式字符串
            string pattern = @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$";

            //验证
            return RegexHelper.IsMatch(ip, pattern);
        }
//csharp/8592