Java8新时间API

本文主要是介绍Java8新时间API，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

import org.junit.Test;

import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalAdjusters;
import java.util.Set;

//Arbor 2022/7/4
public class NewTime {
    @Test
    public void test1(){
        LocalDateTime localDateTime = LocalDateTime.now();
        System.out.println("当前系统时间："+localDateTime);
        LocalDateTime localDateTime3 = localDateTime.minusDays(1);
        System.out.println("减一天"+localDateTime3);
//        Instant() unix元年，1970年1月1日00:00:00,这个不是系统时间
        Instant ins1 = Instant.now();
        System.out.println("utc时间"+ins1);
//        这是utc时间和utc差8小时见差
        OffsetDateTime odt = ins1.atOffset(ZoneOffset.ofHours(8));
        System.out.println("utc时间+8小时"+odt);
        System.out.println("1970年1月1日00:00:00至今毫秒值"+ins1.toEpochMilli());//毫秒值
    }

    @Test
    public void test2(){
        Instant ins1 = Instant.now();
        Instant ins2 = Instant.now();
//        Duration计算两个时间之间间隔
//        Period计算两个日期之间间隔的
//        计算机的时间
        Duration between1 = Duration.between(ins1, ins2);
        System.out.println(between1.toMillis());
//        人看的时间
        LocalDateTime localDateTime1 = LocalDateTime.now();
        LocalDateTime localDateTime2 = LocalDateTime.now();
        Duration between2 = Duration.between(localDateTime1, localDateTime2);
        System.out.println(between2.toMillis());
        LocalDate localDate1 = LocalDate.of(2022,2,2);
        LocalDate localDate2 = LocalDate.now();
        Period period = Period.between(localDate1,localDate2);
        System.out.println(period.getDays());
    }

    @Test
    public void test3(){
//        时间矫正器,设置下一个月，下一个星期几。。
        LocalDateTime localDateTime = LocalDateTime.now();
        System.out.println(localDateTime);
//        指定月的天某一天
        LocalDateTime withDayOfMonth = localDateTime.withDayOfMonth(10);
        System.out.println("指定月的天某一天:"+withDayOfMonth);
        LocalDateTime with = localDateTime.with(TemporalAdjusters.next(DayOfWeek.SUNDAY));
        System.out.println("下一个SUNDAY:"+with);

        LocalDateTime with1 = localDateTime.with((l) -> {
            LocalDateTime ldt4 = (LocalDateTime) l;
            DayOfWeek dayOfWeek = ldt4.getDayOfWeek();
            System.out.println(dayOfWeek);
            return ldt4.plusDays(1);
        });
        System.out.println(with1);
    }

    @Test
    public void Test4(){
//        时间格式化
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ISO_DATE;
        LocalDateTime ldt = LocalDateTime.now();
        String format = ldt.format(dateTimeFormatter);
        System.out.println(format);

//        自定义
        DateTimeFormatter dateTimeFormatter1 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        String format1 = ldt.format(dateTimeFormatter1);
        System.out.println(format1);
//-------------------------------------
        String format2 = dateTimeFormatter1.format(ldt);
        System.out.println(format2);
    }


    @Test
    public void Test5(){
//        时区
        Set<String> availableZoneIds = ZoneId.getAvailableZoneIds();
//        System.out.println("支持的时区:");
//        for (String s:availableZoneIds) {
//            System.out.println(s);
//        }

        LocalDateTime now = LocalDateTime.now(ZoneId.of("Asia/Shanghai"));
        System.out.println("指定时区的时间"+now);
        ZonedDateTime zonedDateTime = now.atZone(ZoneId.of("Asia/Shanghai"));
        System.out.println("指定时区的时间格式时间"+zonedDateTime);

    }
}

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