JDK8中，新增了三个类，用以处理时间。
LocalDate专门处理日期，LocalTime专门处理时间，LocalDateTime包含了日期和时间，而且对于很多复杂的问题，都提供了现成的方法，比如：获取12月的第一个周一等。
package test;import java.time.DayOfWeek;import java.time.LocalDate;import java.time.LocalDateTime;import java.time.LocalTime;import java.time.temporal.TemporalAdjusters;import java.util.Calendar;/*** Created by lightClouds917* Date /11/6* Description:Java8中处理时间和日期的类*SQL -> Java--------------------------date -> LocalDatetime -> LocalTimetimestamp -> LocalDateTime*/public class DateTest2 {public static void main(String[] args){test1();test2();Calendar calendar = Calendar.getInstance();System.out.println(calendar.getTime());}/*** 处理日期 LocalDate*/public static void test1(){//获取当前日期 -11-06LocalDate today = LocalDate.now();System.out.println(today);//构造日期 -10-08LocalDate today2 = LocalDate.of(,10,8);System.out.println(today2);//构造日期 -02-22 字符串严格按照yyyy-MM-ddLocalDate today3 = LocalDate.parse("-02-22");System.out.println(today3);//本月第一天 -11-01LocalDate firstDayOfMonth = today.with(TemporalAdjusters.firstDayOfMonth());System.out.println(firstDayOfMonth);//本月第二天 -11-02 第n天LocalDate secondDayOfMonth = today.withDayOfMonth(2);System.out.println(secondDayOfMonth);//本月最后一天 -02-28 方便解决任何年份的二月份多少天LocalDate lastDayOfMonth = today3.with(TemporalAdjusters.lastDayOfMonth());System.out.println(lastDayOfMonth);//获取12月的第一个周一 -12-04LocalDate firstDayOf12 = LocalDate.parse("-12-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));System.out.println(firstDayOf12);}/*** 处理时间 LocalTime*/public static void test2(){//获取当前时间 含有毫秒值 17:18:41.571LocalTime now = LocalTime.now();System.out.println(now);//获取当前时间 去掉毫秒值 17:45:41LocalTime now1 = LocalTime.now().withNano(0);System.out.println(now1);//00:46:46.651 提供了把时分秒都设为0的方法LocalTime now2 = LocalTime.now().withHour(0);System.out.println(now2);//构造时间 00:20:55LocalTime time1 = LocalTime.of(0,20,55);System.out.println(time1);//构造时间 05:43:22LocalTime time2 = LocalTime.parse("05:43:22");System.out.println(time2);//标准时间 -11-06T17:53:15.930LocalDateTime lt = LocalDateTime.now();System.out.println(lt);}}
及：
public class TimeTest {@Testpublic void testTime() {LocalDateTime time = LocalDateTime.now();System.out.println(time.toString()); //字符串表示System.out.println(time.toLocalTime()); //获取时间(LocalTime)System.out.println(time.toLocalDate()); //获取日期(LocalDate)System.out.println(time.getDayOfMonth()); //获取当前时间月份的第几天System.out.println(time.getDayOfWeek()); //获取当前周的第几天System.out.println(time.getDayOfYear()); //获取当前时间在该年属于第几天System.out.println(time.getHour());System.out.println(time.getMinute());System.out.println(time.getMonthValue());System.out.println(time.getMonth());System.out.println("-----------------------------------");//格式化输出DateTimeFormatter formatter = DateTimeFormatter.ofPattern("YYYY/MM/dd HH:mm:ss");System.out.println(time.format(formatter));//构造时间LocalDateTime startTime = LocalDateTime.of(, 1, 1, 20, 31, 20);LocalDateTime endTime = LocalDateTime.of(, 1, 3, 20, 31, 20);//比较时间System.out.println(time.isAfter(startTime));System.out.println(time.isBefore(endTime));//时间运算，相加相减System.out.println(time.plusYears(2)); //加2年System.out.println(time.plusDays(2)); //加两天System.out.println(time.minusYears(2)); //减两年System.out.println(time.minusDays(2)); //减两天//获取毫秒数(使用Instant)System.out.println(time.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());//获取秒数(使用Instant)System.out.println(time.atZone(ZoneId.systemDefault()).toInstant().getEpochSecond());}}
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