快速获取当天0点0分0秒（00:00:00）

// 获取当天凌晨0点0分0秒Date

        Calendar calendar1 = Calendar.getInstance();

        calendar1.set(calendar1.get(Calendar.YEAR), calendar1.get(Calendar.MONTH), calendar1.get(Calendar.DAY_OF_MONTH),

                0, 0, 0);

        Date beginOfDate = calendar1.getTime();

        System.out.println(beginOfDate);

也可以设置为任一时间

Calendar.HOUR_OF_DAY是24小时制

Calendar.HOUR是12小时制

2022-12-23
2021-08-28
2021-08-01
2022-12-23
2022-12-23
2022-12-23
2022-12-23
2021-11-04