虽然说生成随机数大家都知道.但是要生成指定长度.指定字符组合.随机率在1/2000000.就难了.这是我在做充值卡时写的用来生成充值时写的随机数生成器.也是原创吧.在网上找了一堆不满意,只好自己写了.-generated random number is known to all. However, to generate a specified length. Designated character portfolio. Random rates in the 1 / 2 million. Very difficult. This is my doing prepaid card was used to generate the recharging time to write the random number generator. It is also original. On the Internet to find a heap of dissatisfied, but his writing.