java LocalDateTime

时间戳

当前时间戳： 2020-03-22 23:03:38 变成最这天最开始的时间戳2020-03-21 00:00:00 和最后的时间戳2020-03-21 23:59:59

public static void main(String[] args) {
        LocalDateTime now = LocalDateTime.now();
        // 2020-03-22T23:02:06.940
        System.out.println(now);
        // 1- LocaDateTime to Timestamp
        Timestamp timestamp = Timestamp.valueOf(now);
        // 2020-03-22 23:03:38.049
        System.out.println(timestamp);

        // 2- timestamp to LocalDateTime
        LocalDateTime localDateTime = timestamp.toLocalDateTime();
        //2020-03-22T23:04:57.708
        System.out.println(localDateTime);

        // 3- 昨天，也就是减去一天
        LocalDateTime yesterday = localDateTime.minusDays(1L);
        //2020-03-21T23:06:17.361
        System.out.println(yesterday);
        
        yesterday = yesterday.withHour(0).withMinute(0).withSecond(0);
        // 2020-03-21T00:00:00.337
        System.out.println(yesterday);
        // 2020-03-21 00:00:00.329
        System.out.println(Timestamp.valueOf(yesterday));

        yesterday = yesterday.withHour(23).withMinute(59).withSecond(59);
        // 2020-03-21 23:59:59.197
        System.out.println(Timestamp.valueOf(yesterday));
    }