概述
LocalDateTime：包含了日期及时间。
LocalDate：不包含具体时间的日期。
LocalTime：不含日期的时间。
Instant：代表的是时间戳。
获取日期时间的信息
LocalDateTime
LocalDateTime类获取日期时间信息。格式为 2020-08-04T16:25:34.250
LocalDateTime nowDateTime = LocalDateTime.now();System.out.println("今天是：" + nowDateTime);//今天是：2020-08-04T16:25:34.250System.out.println(nowDateTime.getYear());//年System.out.println(nowDateTime.getMonthValue());//月System.out.println(nowDateTime.getDayOfMonth());//日System.out.println(nowDateTime.getHour());//时System.out.println(nowDateTime.getMinute());//分System.out.println(nowDateTime.getSecond());//秒System.out.println(nowDateTime.getNano());//纳秒//日：当年的第几天System.out.println("dayOfYear：" + nowDateTime.getDayOfYear());//dayOfYear：228//星期System.out.println(nowDateTime.getDayOfWeek());//THURSDAYSystem.out.println(nowDateTime.getDayOfWeek().getValue());//4//月份System.out.println(nowDateTime.getMonth());//SEPTEMBERSystem.out.println(nowDateTime.getMonth().getValue());//8
LocalDate
LocalDate类获取日期信息。格式为 2020-08-04
LocalDate nowDate = LocalDate.now();System.out.println("今天的日期：" + nowDate);//今天的日期： 2020-08-04int year = nowDate.getYear();//年：一般用这个方法获取年System.out.println("year：" + year);//year：2020int month = nowDate.getMonthValue();//月：一般用这个方法获取月System.out.println("month：" + month);//month：8int day = nowDate.getDayOfMonth();//日：当月的第几天，一般用这个方法获取日System.out.println("day：" + day);//day：4int dayOfYear = nowDate.getDayOfYear();//日：当年的第几天System.out.println("dayOfYear：" + dayOfYear);//dayOfYear：249//星期System.out.println(nowDate.getDayOfWeek());//THURSDAYSystem.out.println(nowDate.getDayOfWeek().getValue());//4//月份System.out.println(nowDate.getMonth());//SEPTEMBERSystem.out.println(nowDate.getMonth().getValue());//8
LocalTime
LocalTime类获取时间信息。格式为 15:33:56.749
LocalTime nowTime = LocalTime.now();System.out.println("今天的时间：" + nowTime);//今天的时间：15:33:56.749int hour = nowTime.getHour();//时System.out.println("hour：" + hour);//hour：15int minute = nowTime.getMinute();//分System.out.println("minute：" + minute);//minute：33int second = nowTime.getSecond();//秒System.out.println("second：" + second);//second：56int nano = nowTime.getNano();//纳秒System.out.println("nano：" + nano);//nano：749000000