原创函数

        public static string GetRndID()
        {
            Random md=new Random();
            string mdString=md.Next(1000,10000).ToString();
            return System.String.Concat(DateTime.Now.Year.ToString(),DateTime.Now.Month.ToString("00"),DateTime.Now.Day.ToString("00"),DateTime.Now.Hour.ToString("00"),DateTime.Now.Minute.ToString("00"),DateTime.Now.Second.ToString("00"),mdString);            
        }

        /**//// <summary>
        /// 根据指定的长度截短字符串
        /// </summary>
        /// <param name="topic"></param>
        /// <param name="intLength"></param>
        /// <returns></returns>
        public static string DoTrim(string topic, int intLength)
        {
            if(topic=="")
            {
                return "null";//可以任意写
            }
            else
            {
                topic.Trim();
                if(topic.Length>intLength)
                {
                    return topic.Substring(0,intLength)+".";
                }
                else
                {
                    return topic;
                }
            }
        }

  /// <summary>
  /// 获取一个18位(年月日时分秒+4位随机数)随机数
  /// </summary>
  /// <returns>返回加工过的　随机ID </returns>