Java 8: LocalDate, LocalTime, LocalDateTime gérer la date et l'heure

Dans JDK8, trois nouvelles classes ont été ajoutées pour gérer le temps.

LocalDate se spécialise dans le traitement des dates, LocalTime se spécialise dans le temps de traitement, LocalDateTime inclut la date et l'heure et fournit des méthodes toutes faites pour de nombreux problèmes complexes, tels que l'obtention du premier lundi de décembre 2017.

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 2017/11/6
 * Description:Java8中处理时间和日期的类
 *
 SQL  -> Java
 --------------------------
 date -> LocalDate
 time -> LocalTime
 timestamp -> 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   2017-11-06
        LocalDate today = LocalDate.now();
        System.out.println(today);
 
        //构造日期   2017-10-08
        LocalDate today2 = LocalDate.of(2017,10,8);
        System.out.println(today2);
 
        //构造日期   2017-02-22    字符串严格按照yyyy-MM-dd
        LocalDate today3 = LocalDate.parse("2017-02-22");
        System.out.println(today3);
 
        //本月第一天  2017-11-01
        LocalDate firstDayOfMonth = today.with(TemporalAdjusters.firstDayOfMonth());
        System.out.println(firstDayOfMonth);
        //本月第二天  2017-11-02   第n天
        LocalDate secondDayOfMonth = today.withDayOfMonth(2);
        System.out.println(secondDayOfMonth);
 
        //本月最后一天 2017-02-28  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2017年12月的第一个周一   2017-12-04
        LocalDate firstDayOf201712 = LocalDate.parse("2017-12-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
        System.out.println(firstDayOf201712);
 
    }
 
    /**
     * 处理时间  LocalTime
     */
    public static void test2(){
    
    
        //获取当前时间  含有毫秒值  17:18:41.571
        LocalTime now = LocalTime.now();
        System.out.println(now);
 
        //获取当前时间   去掉毫秒值   17:45:41
        LocalTime 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  00:20:55
        LocalTime time1 = LocalTime.of(0,20,55);
        System.out.println(time1);
        //构造时间  05:43:22
        LocalTime time2 = LocalTime.parse("05:43:22");
        System.out.println(time2);
 
 
        //标准时间 2017-11-06T17:53:15.930
        LocalDateTime lt = LocalDateTime.now();
        System.out.println(lt);
    }
}

public class TimeTest {
    
    
 
    @Test
    public 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(2018, 1, 1, 20, 31, 20);
        LocalDateTime endTime = LocalDateTime.of(2018, 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());
    }
 
}