日期处理

常用日期类：Java。util.Date

public class TestDate {
    public static void main(String[] args) throws Exception{
        //获取今天的日期
        Date today = new Date();
        System.out.println(today);//Sun Aug 09 19:27:13 CST 2020
        //格式化日期
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println(format.format(today));//2020-08-09 19:27:13

        Calendar instance = Calendar.getInstance();
        System.out.println(instance.get(Calendar.DAY_OF_MONTH));//取日：9
        //取2020-10-01为周几
        Date date = new SimpleDateFormat("yyyy-MM-dd").parse("2000-10-01");//抛异常:throws Exception
        instance.setTime(date);
        System.out.println(instance.get(Calendar.DAY_OF_WEEK));//1

    }
}