jdk8在java.time包下新增了一批时间api，使用起来比老的Date更方便；

java.time包下的内容：

常用的LocalDate、LocalTime、LocalDateTime，其他基本都是辅助用，LocalDate只用于年月日，LocalTime只用于时分秒，LocalDateTime可用于年月日时分秒，这三个类的方法都比较相似；

可以通过now()方法获得系统当前时间：

@Test
	public void test() {
		LocalDate ld = LocalDate.now();
		System.out.println(ld);
		LocalTime lt = LocalTime.now();
		System.out.println(lt);
		
		LocalDateTime ldt = LocalDateTime.now();
		System.out.println(ldt);
		ldt = LocalDateTime.now(Clock.systemDefaultZone());
		System.out.println(ldt);
		ldt = LocalDateTime.now(ZoneId.of("Asia/Shanghai"));
		System.out.println(ldt);
		
//		ZoneId.getAvailableZoneIds().stream().forEach(System.out::println);//查看所有可用的时区
	}

也可以直接指定时间，或者自定义格式创建：

@Test
	public void test() {
		System.out.println("[LocalDate]");
		LocalDate ld = LocalDate.of(2000, 6, 6);
		System.out.println(ld);
		ld = LocalDate.of(2000, Month.JUNE, 6);
		System.out.println(ld);
		ld = LocalDate.ofEpochDay(32L);//0是1970-1-1
		System.out.println(ld);
		ld = LocalDate.ofYearDay(1970, 32);
		System.out.println(ld);
		
		System.out.println("[LocalTime]");
		LocalTime lt = LocalTime.of(10, 20);
		System.out.println(lt);
		lt = LocalTime.of(10, 20, 30);
		System.out.println(lt);
		lt = LocalTime.of(10, 20, 30, 123456);
		System.out.println(lt);
		lt = LocalTime.ofNanoOfDay(60 * 1000000000L);
		System.out.println(lt);
		lt = LocalTime.ofSecondOfDay(60L);
		System.out.println(lt);
		
		System.out.println("[LocalDateTime]");
		LocalDateTime ldt = LocalDateTime.of(ld, lt);
		System.out.println(ldt);
		ldt = LocalDateTime.of(2022, 2, 22, 22, 22);
		System.out.println(ldt);
		ldt = LocalDateTime.of(2022, Month.FEBRUARY, 22, 22, 22);
		System.out.println(ldt);
		ldt = LocalDateTime.of(1999, 3, 4, 5, 6, 7);
		System.out.println(ldt);
		ldt = LocalDateTime.of(1999, Month.MARCH, 4, 5, 6, 7);
		System.out.println(ldt);
		ldt = LocalDateTime.of(2000, 1, 10, 20, 30, 40, 50);
		System.out.println(ldt);
		ldt = LocalDateTime.of(2000, Month.JANUARY, 10, 20, 30, 40, 50);
		System.out.println(ldt);
		ldt = LocalDateTime.ofEpochSecond(62, 70, ZoneOffset.ofHours(8));
		System.out.println(ldt);
		ldt = LocalDateTime.ofInstant(Instant.now(), ZoneId.systemDefault());
		System.out.println(ldt);
		
		System.out.println("=========================");
		System.out.println(LocalDate.from(ldt));
		System.out.println(LocalTime.from(ldt));
		System.out.println(LocalDateTime.from(ldt));
		System.out.println(LocalDate.parse("1999-01-01"));//格式固定为 xxxx-xx-xx （DateTimeFormatter.ISO_LOCAL_DATE的格式）
		System.out.println(LocalTime.parse("12:34:56"));//格式为 xx:xx 或者 xx:xx:xx （DateTimeFormatter.ISO_LOCAL_TIME的格式）
		System.out.println(LocalDateTime.parse("1999-01-01T12:34"));//Date格式和Time格式中间用字母T连接（DateTimeFormatter.ISO_LOCAL_DATE_TIME的格式）
		System.out.println(LocalDate.parse("自定义2222年，02月，22日13:14:15:666666666", DateTimeFormatter.ofPattern("自定义yyyy年，MM月，dd日HH:mm:ss:SSSSSSSSS")));//只识别日期
		System.out.println(LocalTime.parse("自定义2222年，02月，22日13:14:15:666", DateTimeFormatter.ofPattern("自定义yyyy年，MM月，dd日HH:mm:ss:SSS")));//只识别时间
		System.out.println(LocalDateTime.parse("自定义2222年，02月，22日13:14:15:666666666", DateTimeFormatter.ofPattern("自定义yyyy年，MM月，dd日HH:mm:ss:SSSSSSSSS")));
	}

可对日期时间进行操作，3个类的方法基本类似，常用的方法：

@Test
	public void test() {
		LocalDateTime ldt = LocalDateTime.of(1999, 1, 2, 3, 4, 5, 6);
		System.out.println(ldt);
		System.out.println(ldt.getYear());
		System.out.println(ldt.getHour());
		System.out.println(ldt.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH点mm分ss秒")));
		LocalDateTime newldt = ldt.withYear(2000).withHour(23).withSecond(59);
		System.out.println(ldt);
		System.out.println(newldt);
		System.out.println(ldt.isBefore(newldt));
		newldt = ldt.plusYears(0).plusMonths(13).plusDays(27).minusHours(2);
		System.out.println(newldt);
		newldt = ldt.plusYears(1).plusMonths(13).plusDays(27).minusHours(2);
		System.out.println(newldt);
		System.out.println(ldt.toLocalDate());
	}

Instant用于记录某一时刻，跟Date差不多，两者可以互转，功能比Date多：

@Test
	public void test() {
		Instant instant = Instant.now();
		System.out.println(instant);
		Date d = Date.from(instant);
		System.out.println(d);
		System.out.println(d.toInstant());
		
		System.out.println(Instant.ofEpochMilli(60 * 60 * 1000L));
		System.out.println(Instant.parse("2000-11-11T01:02:03.456789Z"));//格式为 xxxx-xx-xxTxx:xx:xx.xxxZ
		
		Instant newInstant = instant.plusSeconds(3600L);
		System.out.println(newInstant);
		newInstant = instant.minusMillis(10 * 1000L);
		System.out.println(newInstant);
		System.out.println(instant.isBefore(newInstant));
	}

Duration可以用于计算时间间隔（时分秒），不能用于LocalDate，计算LocalDate之间的日期间隔需要使用Period：

@Test
	public void test() {
		LocalDateTime ldt1 = LocalDateTime.of(2000, 1, 1, 1, 1, 1);
		LocalDateTime ldt2 = LocalDateTime.of(2000, 1, 2, 2, 1, 1);
		Duration duration = Duration.between(ldt1, ldt2);
		System.out.println(duration);
		LocalTime lt1 = LocalTime.of(1, 1);
		LocalTime lt2 = LocalTime.of(2, 2);
		Duration d = Duration.between(lt1, lt2);
		System.out.println(d);
		System.out.println(d.toMinutes());
		System.out.println(d.getSeconds());
	}

@Test
	public void test() {
		LocalDate ld1 = LocalDate.of(1999, 1, 1);
		LocalDate ld2 = LocalDate.of(2001, 4, 6);
		Period p = Period.between(ld1, ld2);
		System.out.println(p);
		System.out.println(p.getYears());
		System.out.println(p.getMonths());
		System.out.println(p.getDays());
		System.out.println(p.toTotalMonths());
	}

还有一些其他的类：

@Test
	public void test() {
		MonthDay md = MonthDay.now();
		System.out.println(md);
		Year y = Year.now();
		System.out.println(y);
		YearMonth ym = YearMonth.now();
		System.out.println(ym);
		ym = YearMonth.of(1, 2);
		System.out.println(ym);
		
		ZonedDateTime zdt = ZonedDateTime.now();
		System.out.println(zdt);
		ZoneOffset zo = ZoneOffset.of("+8");
		System.out.println(zo);
		zo = ZoneOffset.ofHoursMinutes(8, 30);
		System.out.println(zo);
		
		OffsetDateTime odt = OffsetDateTime.now();
		System.out.println(odt);
		OffsetTime ot = OffsetTime.now();
		System.out.println(ot);
		ot = OffsetTime.now(ZoneId.of("+9"));
		System.out.println(ot);
	}