一、JDK Release Notes：
https://www.oracle.com/technetwork/java/javase/jdk-relnotes-index-2162236.html?ssSourceSiteId=otncn
https://docs.oracle.com/javase/9/docs/api/java/time/package-summary.html
二、API Specification(API 规范)
包介绍：
java.time - Classes for date, time, date and time combined, time zones, instants, duration, and clocks.
java.time.chrono - API for representing calendar systems other than ISO-8601. Several predefined chronologies are provided and you can also define your own chronology.
java.time.format - Classes for formatting and parsing dates and time.
java.time.temporal - Extended API, primarily for framework and library writers, allowing interoperations between the date and time classes, querying, and adjustment. Fields and units are defined in this package.
java.time.zone - Classes that support time zones, offsets from time zones, and time zone rules.
类介绍：
Clock
A clock providing access to the current instant, date and time using a time-zone.
LocalDate
A date without a time-zone in the ISO-8601 calendar system, such as 2007-12-03.
LocalDateTime
A date-time without a time-zone in the ISO-8601 calendar system, such as 2007-12-03T10:15:30.
LocalTime
A time without a time-zone in the ISO-8601 calendar system, such as 10:15:30.
ZonedDateTime (带时区的时间，不常用)
A date-time with a time-zone in the ISO-8601 calendar system, such as 2007-12-03T10:15:30+01:00 Europe/Paris.
DateTimeException
三、LocalDate、LocalTime、LocalDateTime常用方法介绍（线程安全）
1）可理解为 LocalDateTime = LocalDate + LocalTime
2）格式不正确可能导致类型转换处理异常
3）简单介绍基本类的常用情况、其他可自行扩展
1、LocalDate: 返回日期格式，如2019-01-01
//返回当前日期
System.out.println(LocalDate.now());
//返回指定日期（注意字段取值范围如月份取值1-12）
System.out.println(LocalDate.of(2019, 11, 30));
//返回一年种的第几天是多少号
System.out.println(LocalDate.ofYearDay(2019, 12));
//String and LocalDate 转换 （注意时间格式，其他格式导致异常）
System.out.println(LocalDate.parse("2017-12-03"));
System.out.println(LocalDate.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
//日期加减计算
LocalDate localDate ＝ LocalDate.now()；
System.out.println(localDate.plusDays(1));
System.out.println(localDate.minusDays(3));
//单独取年、月、日方法
System.out.println(localDate.getYear() + "年" + localDate.getMonth().getValue() + "月" + localDate.getDayOfMonth() + "日");
2、LocalTime: 返回格式，如10:15:30
//当前时间 格式10:57:11.551
LocalTime localTime = LocalTime.now();
System.out.println(localTime);
System.out.println(localTime.withNano(0));
//返回指定的时间和分钟,秒和纳秒;不设置默认0
System.out.println(LocalTime.of(1, 1));
System.out.println(LocalTime.of(1, 1, 1));
System.out.println(LocalTime.of(1, 1, 1, 999));
//每天的第几秒开始、可用于计时器，参考示例如下
System.out.println(LocalTime.ofSecondOfDay(1));//00:00:01
System.out.println(LocalTime.ofSecondOfDay(60));//00:01
//替换指定时间单位上的值
System.out.println(localTime.withHour(1));
System.out.println(localTime.withMinute(2));
System.out.println(localTime.withSecond(3).withNano(1));
//时间的加减操作
System.out.println(localTime.plusHours(1));
System.out.println(localTime.plusMinutes(2));
System.out.println(localTime.plusSeconds(3));
System.out.println(localTime.plusNanos(100));
//其他同上
System.out.println(localTime.minusHours(1));
//LocalTime and Str 转换(注意格式化不可添加年月日)
System.out.println(localTime.format(DateTimeFormatter.ofPattern("hh:mm:ss")));
System.out.println(LocalTime.parse("10:01:01"));
//LocalDate to LocalDateTime（注意格式） 2019-03-04T15:42:22.233
System.out.println(localTime.atDate(LocalDate.now()));
//时间比较，返回int值
System.out.println(localTime.compareTo(localTime));
//时间比较，返回boolean值（注意格式和单位）
System.out.println("当前时间比较，注意纳秒不同：" + localTime + "||" + LocalTime.now());
System.out.println(localTime.isBefore(LocalTime.now()) + "||" + localTime.isAfter(LocalTime.now()));
System.out.println(localTime.withNano(0).isBefore(LocalTime.now().withNano(0)) + "||" + localTime.withNano(0).isAfter(LocalTime.now().withNano(0)));
System.out.println(localTime.equals(LocalTime.now()) + "||" + localTime.withNano(0).equals(LocalTime.now().withNano(0)));
3、LocalDateTime 返回格式，如2019-03-04T15:48:29.254
//基本使用及时间比较
LocalDateTime localDateTime = LocalDateTime.now();
System.out.println(localDateTime);
System.out.println(localDateTime.withNano(0));
System.out.println(localDateTime.compareTo(LocalDateTime.now()));
System.out.println(localDateTime.isAfter(localDateTime));
System.out.println(localDateTime.isBefore(localDateTime));
System.out.println(localDateTime.isEqual(localDateTime));
//LocalDateTime and Str 转换
System.out.println(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss").format(LocalDateTime.now()));
System.out.println(LocalDateTime.parse("2018-01-12 17:07:05", DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
System.out.println(LocalDateTime.parse("2019-03-04T15:48:29.254").format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
