猜数游戏 系统生成一个随机数，用户从输入框输入自己的猜测。如果小于随机数，背景变蓝，否则变红。北京化工大学java上机作业(Guessing game The system generates a random number, and the user enters its own guesswork from the input box. If it is less than the random number, the background becomes blue, otherwise