//获取当前时间
System.out.println(LocalDateTime.now());
//获取当前时间时分秒
System.out.println(LocalDateTime.now().toLocalTime());
//获取当前时间年月日
System.out.println(LocalDateTime.now().toLocalDate());
//获取当前时间20天之前
System.out.println(LocalDateTime.now().minusDays(20));
//获取当前时间20天之后
System.out.println(LocalDateTime.now().plusDays(20));
//获取当前时间60天之前
System.out.println(LocalDateTime.now().minusDays(60));
//所有minus开头都是之前 plus开头都是之后
//比较大小
System.out.println(LocalDateTime.now().compareTo(LocalDateTime.now().plusDays(2)));
//实例化方式 以及比较大小
Duration between = Duration.between(LocalDateTime.of(1993,3,14,0,0), LocalDateTime.now());
Duration between2 = Duration.between(LocalDateTime.of(1993,3,14,0,0), LocalDateTime.now());
System.out.println(between.toDays());
System.out.println(between2.toDays());
java.time.Duration duration = java.time.Duration.between(LocalDateTime startTime, LocalDateTime endTime );
例如: duration.toMinutes() //两个时间差的分钟数
toNanos()//纳秒
toMillis()//毫秒
toMinutes()//分钟
toHours()//小时
toDays()//天数
//获取当前是第几日
System.out.println(LocalDateTime.now().getDayOfMonth());
//获取当前周几
System.out.println(LocalDateTime.now().getDayOfWeek().getValue());
//获取当前是今年第几天
System.out.println(LocalDateTime.now().getDayOfYear());
//获取毫秒数
Long milliSecond = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
1.获取当前年月日的字符串
String ymd = LocalDate.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));