java与android和Keil通信。计算驾校学员还需打卡时间。Keil向java服务器传输打卡的卡号，java保存打卡时间，计算两次打卡间隔。android查询某个卡还需的打卡时间。-java and android and Keil communications. Driving students need to punch time calculation. Keil java server to transfer the punch card, punch java save time