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Java 8 新的日期时间 API

Java

发布于：2022年7月5日

Java 8 new date time API

编号 类的名称 描述
1 Instant 时间戳
2 Duration 持续时间，时间差
3 LocalDate 只包含日期，比如 2018-02-05
4 LocalTime 只包含时间，比如 23:12:10
5 LocalDateTime 包含日期和时间，比如 2018-02-05 23:14:21
6 Period 时间段
7 ZoneId 时区
8 ZoneOffset 时区偏移量，比如 +8:00
9 ZonedDateTime 带时区的时间
10 Clock 时钟，比如获取目前美国纽约的时间
11 java.time.format.DateTimeFormatter 时间格式化

Instant 时间戳

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package com.smobob.datetime;

import java.time.Instant;

/**
 * Instant类在Java日期与时间功能中，表示了时间线上一个确切的点，
 * 定义为距离初始时间的时间差（初始时间为GMT 1970年1月1日00:00）经测量一天有86400秒，
 * 从初始时间开始不断向前移动。
 */
public class InstantExample {

    public static void main(String[] args) {
        // 创建一个Instant实例
        Instant now = Instant.now();

        // 访问Instant的时间
        //距离初始时间的秒钟数
        long seconds = now.getEpochSecond();
        System.out.println("seconds: " + seconds);
        //在当前一秒内的第几纳秒
        int nanos = now.getNano();
        System.out.println("nanos: " + nanos);

        //当前时间
        System.out.println("current: " + now.toString());
        // 3秒后
        Instant later = now.plusSeconds(3);
        System.out.println("later: " + later);
        // 3秒前
        Instant earlier = now.minusSeconds(3);
        System.out.println("earlier: " + earlier);
    }

}

Duration 持续时间，时间差

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package com.smobob.datetime;

import java.time.Duration;
import java.time.Instant;
import java.time.LocalDateTime;

public class DurationExample {

    public static void main(String[] args) throws InterruptedException {
        // 创建Duration实例
        Instant first = Instant.now();
        Thread.sleep(3000);
        Instant second = Instant.now();
        Duration duration = Duration.between(first, second);
        // 访问Duration的时间
        long seconds = duration.getSeconds();
        System.out.println("相差: " + seconds + " 秒");

        LocalDateTime from = LocalDateTime.now();
        LocalDateTime to = from.plusDays(5);
        Duration duration2 = Duration.between(from, to);
        System.out.println("从 from 到 to 相差: " + duration2.toDays() + " 天");
    }

}

LocalDate 只包含日期

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package com.smobob.datetime;

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.Month;

public class LocalDateExample {

    public static void main(String[] args) {
        // 创建一个LocalDate实例
        LocalDate localDate = LocalDate.now();

        int year = localDate.getYear();
        Month month = localDate.getMonth();
        int dayOfMonth = localDate.getDayOfMonth();
        int dayOfYear = localDate.getDayOfYear();
        DayOfWeek dayOfWeek = localDate.getDayOfWeek();

        System.out.println("year: " + year);
        System.out.println("month: " + month.getValue());
        System.out.println("dayOfMonth: " + dayOfMonth);
        System.out.println("dayOfYear: " + dayOfYear);
        System.out.println("dayOfWeek: " + dayOfWeek.getValue());

        // 使用年月日信息构造出LocalDate对象
        LocalDate localDate2 = LocalDate.of(2018, 3, 3);
        // 3年后
        LocalDate d1 = localDate2.plusYears(3);
        System.out.println("plusYears: " + d1);
        // 3年前
        LocalDate d2 = localDate2.minusYears(3);
        System.out.println("minusYears: " + d2);
    }

}

LocalTime 只包含时间

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package com.smobob.datetime;

import java.time.LocalTime;

public class LocalTimeExample {

    public static void main(String[] args) {
        // 创建一个LocalTime实例
        LocalTime localTime = LocalTime.now();

        // 使用指定的时分秒和纳秒来新建对象
        LocalTime localTime2 = LocalTime.of(21, 30, 59, 11001);

        // 3小时后
        LocalTime localTimeLater = localTime.plusHours(3);
        // 3小时前
        LocalTime localTimeEarlier = localTime.minusHours(3);

        System.out.println("localTime: " + localTime);
        System.out.println("localTime2: " + localTime2);
        System.out.println("localTimeLater: " + localTimeLater);
        System.out.println("localTimeEarlier: " + localTimeEarlier);
    }

}

LocalDateTime 包含日期和时间

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package com.smobob.datetime;

import java.time.LocalDateTime;

public class LocalDateTimeExample {

    public static void main(String[] args) {
        // 创建一个LocalDateTime实例
        LocalDateTime localDateTime = LocalDateTime.now();

        // 使用指定的年月日、时分秒、纳秒来新建对象
        LocalDateTime localDateTime2 = LocalDateTime.of(2018, 11, 26, 13, 55, 36, 123);

        // 3年后的现在
        LocalDateTime dt1 = localDateTime.plusYears(3);
        // 3年前的现在
        LocalDateTime dt2 = localDateTime.minusYears(3);

        System.out.println("localDateTime: " + localDateTime);
        System.out.println("localDateTime2: " + localDateTime2);
        System.out.println("dt1: " + dt1);
        System.out.println("dt2: " + dt2);
    }

}

Period 时间段

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package com.smobob.datetime;

import java.time.LocalDate;
import java.time.Period;

public class PeriodExample {

    public static void main(String[] args) {
        LocalDate today = LocalDate.now();
        LocalDate java8Release = LocalDate.of(2018, 12, 14);
        Period periodToNextJavaRelease = Period.between(today, java8Release);
        System.out.println("Months left between today and Java 8 release : " + periodToNextJavaRelease.getMonths());
    }

}

ZoneId 时区

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package com.smobob.datetime;

import java.time.ZoneId;
import java.util.TimeZone;

public class ZoneIdExample {

    public static void main(String[] args) {
        // 获取系统默认时区
        ZoneId defaultZoneId = ZoneId.systemDefault();
        System.out.println(defaultZoneId);

        //接收一个“区域/城市”的字符串作为参数获取时区
        ZoneId shanghaiZoneId = ZoneId.of("Asia/Shanghai");
        System.out.println(shanghaiZoneId);

        // TimeZone 转换为 ZoneId
        ZoneId oldToNewZoneId = TimeZone.getDefault().toZoneId();
        System.out.println(oldToNewZoneId);

        //获取所有合法的“区域/城市”字符串
        System.out.println(ZoneId.getAvailableZoneIds());
    }

}

ZoneOffset 时区偏移量

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package com.smobob.datetime;

import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.time.ZoneOffset;

public class ZoneOffsetExample {

    public static void main(String[] args) {
        LocalDateTime localDateTime = LocalDateTime.now();
        System.out.println("localDateTime: " + localDateTime);

        OffsetDateTime odt = OffsetDateTime.now();
        ZoneOffset zoneOffset1 = odt.getOffset();
        System.out.println("zoneOffset1: " + zoneOffset1);
        OffsetDateTime offsetDateTime1 = OffsetDateTime.of(localDateTime, zoneOffset1);
        System.out.println("offsetDateTime1: " + offsetDateTime1);

        ZoneOffset zoneOffset2 = ZoneOffset.of("+09:00");
        System.out.println("zoneOffset2: " + zoneOffset2);
        OffsetDateTime offsetDateTime2 = OffsetDateTime.of(localDateTime, zoneOffset2);
        System.out.println("offsetDateTime2: " + offsetDateTime2);
    }

}

ZonedDateTime 带时区的时间

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package com.smobob.datetime;

import java.time.Period;
import java.time.ZoneId;
import java.time.ZonedDateTime;

public class ZonedDateTimeExample {

    public static void main(String[] args) {
        // 创建一个ZonedDateTime实例
        ZonedDateTime dateTime = ZonedDateTime.now();
        System.out.println("dateTime: " + dateTime);
        System.out.println("zoneDateTime : " + dateTime);

        // 使用指定的年月日、时分秒、纳秒以及时区ID来新建对象
        ZoneId zoneId = ZoneId.of("UTC+8");
        ZonedDateTime dateTime2 = ZonedDateTime.of(2018, 3, 8, 23, 45, 59, 1234, zoneId);

        // 3天后
        ZonedDateTime zoneDateTime = dateTime2.plus(Period.ofDays(3));
        System.out.println("zoneDateTime : " + zoneDateTime);

        ZoneId zoneId2 = ZoneId.of("Europe/Copenhagen");
        ZoneId zoneId3 = ZoneId.of("Europe/Paris");

        System.out.println("zoneId2: " + zoneId2);
        System.out.println("zoneId3: " + zoneId3);
    }

}

Clock 时钟

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package com.smobob.datetime;

import java.time.Clock;
import java.time.Instant;
import java.util.Date;

public class ClockExample {

    public static void main(String[] args) {
        Clock clock = Clock.systemDefaultZone();
        long millis = clock.millis();
        Instant instant = clock.instant();
        Date legacyDate = Date.from(instant);
        System.out.println(millis);
        System.out.println(legacyDate);
    }

}

DateTimeFormatter 时间格式化

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package com.smobob.datetime;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class DateTimeFormatExample {

    public static void main(String[] args) {
        DateTimeFormatter formatter = DateTimeFormatter.BASIC_ISO_DATE;
        String formattedDate = formatter.format(LocalDate.now());
        String formattedZonedDate = formatter.format(ZonedDateTime.now());

        System.out.println("LocalDate: " + formattedDate);
        System.out.println("formattedZonedDate: " + formattedZonedDate);

        LocalDateTime dateTime = LocalDateTime.now();
        // 20180303
        String strDate1 = dateTime.format(DateTimeFormatter.BASIC_ISO_DATE);
        // 2013-03-03
        String strDate2 = dateTime.format(DateTimeFormatter.ISO_LOCAL_DATE);
        // 当前时间
        String strDate3 = dateTime.format(DateTimeFormatter.ISO_LOCAL_TIME);
        // 2018-03-03
        String strDate4 = dateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd"));
        // 今天是：2018年 三月 03日 星期六
        String strDate5 = dateTime.format(DateTimeFormatter.ofPattern("今天是：YYYY年 MMMM dd日 E", Locale.CHINESE));

        System.out.println(strDate1);
        System.out.println(strDate2);
        System.out.println(strDate3);
        System.out.println(strDate4);
        System.out.println(strDate5);

        // 将一个字符串解析成一个日期对象
        String strDate6 = "2018-03-03";
        String strDate7 = "2017-03-03 15:30:05";
        LocalDate date = LocalDate.parse(strDate6, DateTimeFormatter.ofPattern("yyyy-MM-dd"));
        System.out.println(date);
        LocalDateTime dateTime1 = LocalDateTime.parse(strDate7, DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
        System.out.println(dateTime1);
    }

}

日期转换示例

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package com.smobob.datetime;

import java.time.*;
import java.util.Date;

public class ConvertExample {

    /**
     * LocalDate -> Date
     *
     * @param localDate
     * @return
     */
    public static Date toDate(LocalDate localDate) {
        ZoneId zone = ZoneId.systemDefault();
        Instant instant = localDate.atStartOfDay().atZone(zone).toInstant();
        return Date.from(instant);
    }

    /**
     * LocalDateTime -> Date
     *
     * @param localDateTime
     * @return
     */
    public static Date toDate(LocalDateTime localDateTime) {
        ZoneId zone = ZoneId.systemDefault();
        Instant instant = localDateTime.atZone(zone).toInstant();
        return Date.from(instant);
    }

    /**
     * LocalTime -> Date
     *
     * @param localTime
     * @return
     */
    public static Date toDate(LocalTime localTime) {
        LocalDate localDate = LocalDate.now();
        LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime);
        ZoneId zone = ZoneId.systemDefault();
        Instant instant = localDateTime.atZone(zone).toInstant();
        return Date.from(instant);
    }

    /**
     * Date -> LocalDate
     *
     * @param date
     * @return
     */
    public static LocalDate toLocalDate(Date date) {
        Instant instant = date.toInstant();
        ZoneId zone = ZoneId.systemDefault();
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
        return localDateTime.toLocalDate();
    }

    /**
     * Date -> LocalDateTime
     *
     * @param date
     * @return
     */
    public static LocalDateTime toLocalDateTime(Date date) {
        Instant instant = date.toInstant();
        ZoneId zone = ZoneId.systemDefault();
        return LocalDateTime.ofInstant(instant, zone);
    }

    /**
     * Date -> LocalTime
     *
     * @param date
     * @return
     */
    public static LocalTime toLocalTime(Date date) {
        Instant instant = date.toInstant();
        ZoneId zone = ZoneId.systemDefault();
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
        return localDateTime.toLocalTime();
    }

}

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本文永久链接是：https://www.smobob.com/Java/8/datetime-api.html

更新于：2022年7月5日

Java

Java8