/// <summary>
        /// 根据日期和随机码生成订单号
        /// </summary>
        /// <returns></returns>
        public string GetOrderNumber()
        {
            string num = DateTime.Now.ToString("yyMMddHHmmss");//yyyyMMddHHmmssms
            return num + Number(2, false).ToString();
        }
        /// <summary>
        /// 生成随机数字
        /// </summary>
        /// <param name="Length">生成长度</param>
        /// <param name="Sleep">是否要在生成前将当前线程阻止以避免重复</param>
        /// <returns></returns>
        public string Number(int Length, bool Sleep)
        {
            if (Sleep)
                System.Threading.Thread.Sleep(3);
            string result = "";
            System.Random random = new Random();
            for (int i = 0; i < Length; i++)
            {
                result += random.Next(10).ToString();
            }
            return result;
        }
原文:http://www.cnblogs.com/sunzhenyong/p/4389102.html