生成随机数

  /// <summary>
        /// 生成随机数
        /// </summary>
        /// <returns></returns>
        private static String GetSaltValue()
        {
            StringBuilder saltvalue = new StringBuilder();
            Random ran = new Random();
            for (int i = 0; i < 5; i++)
            {
                if (i % 2 == 0)
                {
                    saltvalue.Append(ran.Next(0, 10).ToString());
                }
                else
                {
                    saltvalue.Append(("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ").Substring(ran.Next(0, 52), 1));
                }
            }
            String strSalt = saltvalue.ToString() + DateTime.Now.ToString();
            return strSalt;
        }

//返回随机数+当前时间