概述

特点：
线程安全，不可变。

时间日期：
年月日：LocalDate
时分秒：LocalTime
年月日时分秒：LocalDateTime

时间戳：Instant

时间间隔：
DateTime，Instant的间隔：Duration
LocalDate的间隔：Period

简单操作

当前时间

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

指定时间

LocalDate localDate = LocalDate.of(1234, 1, 2);
LocalTime localTime = LocalTime.of(1, 2, 3);
LocalDateTime localDateTime = LocalDateTime.of(1, 2, 3, 4, 5, 6);

System.out.println(localDate);
System.out.println(localTime);
System.out.println(localDateTime);

今天周几

LocalDateTime now = LocalDateTime.now();
DayOfWeek day = now.getDayOfWeek();
System.out.println(day.toString());

七天后

LocalDateTime now = LocalDateTime.now();
LocalDateTime newTime = now.plusDays(7L);

System.out.println(newTime);

距离2000年1月1日有多久

LocalDate a = LocalDate.of(2000, 1, 1);
LocalDate b = LocalDate.now();
Period result = Period.between(a, b);

System.out.println(result.getYears());
System.out.println(result.getMonths());
System.out.println(result.getDays());

字符串相关

变字符串

LocalDateTime a = LocalDateTime.now();
DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss");
String str = format.format(a);

System.out.println(str);

由字符串得到

String a = "2018-01-13 21:27:30";
DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime result = LocalDateTime.parse(a, format);

System.out.println(result);

小案例

距离2000年1月1日有多少天

翻了一下API，日期的间隔无法做到，故用时间的：

LocalDateTime a = LocalDateTime.of(2000, 1, 1, 0, 0, 0);
LocalDateTime b = LocalDateTime.now();
Duration result = Duration.between(a, b);

System.out.println(result.toDays());