Android基础之——CountDownTimer类，轻松实现倒计时功能
https://www.cnblogs.com/yfceshi/p/6853746.html
android中获取验证码后出现60秒的倒计时
https://blog.****.net/qq_15907463/article/details/52370667
Android三种超简单办法，实现按钮倒计时
https://www.jianshu.com/p/6e72527c03af
Android基础之——CountDownTimer类，轻松实现倒计时功能
https://www.cnblogs.com/yfceshi/p/6853746.html
android中获取验证码后出现60秒的倒计时
https://blog.****.net/qq_15907463/article/details/52370667
Android三种超简单办法，实现按钮倒计时
https://www.jianshu.com/p/6e72527c03af