1. SimpleDateFormat

 1.1 日期转换为字符串

        SimpleDateFormat simpleDateFormat =new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        Date date = new Date();
        System.out.println(simpleDateFormat.format(date));

  1.2 字符串转换为日期

Date date1 = simpleDateFormat.parse("2022-03-05 01:15:37");

 2. LocalDate、LocalTime、LocalDateTime

        LocalDate localDate = LocalDate.now();
        LocalTime localTime = LocalTime.now();
        LocalDateTime localDateTime = LocalDateTime.now();
        System.out.println(localDate);
        System.out.println(localTime);
        System.out.println(localDateTime);

  2.1 新版日期转字符串

        LocalDateTime localDateTime = LocalDateTime.now();
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss");
        String s = dateTimeFormatter.format(localDateTime);
        System.out.println(s);