jdk 1.8 之 LocalDate、LocalTime、LocalDateTime 试用

注意: LocalDate、LocalTime、LocalDateTime、Instant,这几个类的所有属性,都有 final 修饰符,所以,所有修改这些类属性的方法,都会返回一个新的对象副本。如果还是使用原来的对象,修改无效

1, 获取时间

        // LocalDate

        // 获取当前日期
        LocalDate localDate = LocalDate.now();                       // 2020-07-07
        // 获取年
        int year1 = localDate.getYear();                             // 2020
        int year2 = localDate.get(ChronoField.YEAR);                 // 2020
        // 获取月
        Month month1 = localDate.getMonth();                         // JULY
        int month2 = localDate.getMonthValue();                      // 7
        int month3 = localDate.get(ChronoField.MONTH_OF_YEAR);       // 7
        // 获取日
        int dayOfMonth1 = localDate.getDayOfMonth();                 // 7
        int dayOfMonth2 = localDate.get(ChronoField.DAY_OF_MONTH);   // 7


        // LocalTime

        // 获取当前时间
        LocalTime localTime = LocalTime.now();                      // 17:11:55.956
        // 获取时
        int hour1 = localTime.getHour();                            // 17
        int hour2 = localTime.get(ChronoField.HOUR_OF_DAY);         // 17
        // 获取分
        int minute1 = localTime.getMinute();                        // 11
        int minute2 = localTime.get(ChronoField.MINUTE_OF_HOUR);    // 11
        // 获取秒
        int second1 = localTime.getSecond();                        // 55
        int second2 = localTime.get(ChronoField.SECOND_OF_MINUTE);  // 55


        // LocalDateTime

        // 获取当前日期和时间
        LocalDateTime localDateTime = LocalDateTime.now();           // 2020-07-07T17:22:13.067
        // 获取LocalDate对象
        LocalDate localDate4 = localDateTime.toLocalDate();          // 2020-07-07
        // 获取LocalTime对象
        LocalTime localTime4 = localDateTime.toLocalTime();          // 17:22:13.067
        // 获取年
        int year4 = localDateTime.getYear();                         // 2020
        // 获取月
        int month4 = localDateTime.getMonthValue();                  // 7
        // 获取日
        int dayOfMonth4 = localDate.getDayOfMonth();                 // 7

        // 获取时
        int hour4 = localDateTime.getHour();                         // 17
        // 获取分
        int minute4 = localDateTime.getMinute();                     // 22
        // 获取秒
        int second4 = localTime.getSecond();                         // 13


        // Instant

        // 获取Instant对象
        Instant instant = Instant.now();
        // 获取从1970-01-01T00:00:00Z以来的秒数
        long curSecond = instant.getEpochSecond();                  // 1594120503
        // 获取从1970-01-01T00:00:00Z以来的毫秒数
        long curMilli = instant.toEpochMilli();                     // 1594120503969

2, 修改时间

        // LocalDateTime
        
        // 创建日期时间 2020-07-06 20:23:57
        LocalDateTime localDateTime = LocalDateTime.of(2020, 7, 6, 20, 23, 57);
        // 修改年
        localDateTime = localDateTime.withYear(2019);                      // 2019-07-06 20:23:57
        localDateTime = localDateTime.with(ChronoField.YEAR, 2021);        // 2021-07-06 20:23:57
        // 修改月
        localDateTime = localDateTime.withMonth(9);                        // 2021-09-06 20:23:57
        // 修改日
        localDateTime = localDateTime.withDayOfMonth(8);                   // 2021-09-08 20:23:57
        // 修改时
        localDateTime = localDateTime.withHour(5);                         // 2021-09-08 05:23:57
        // 修改分
        localDateTime = localDateTime.withMinute(6);                       // 2021-09-08 05:06:57
        // 修改秒
        localDateTime = localDateTime.withSecond(8);                       // 2021-09-08 05:06:08

3, 解析时间

        // 预置格式
        // 2020-05-30
        LocalDate localDate1 = LocalDate.parse("20200530", DateTimeFormatter.BASIC_ISO_DATE);
        // 2020-05-30
        LocalDate localDate2 = LocalDate.parse("2020-05-30", DateTimeFormatter.ISO_LOCAL_DATE);
        // 2020-05-30T08:46:32
        LocalDateTime localDateTime1 = LocalDateTime.parse("2020-05-30T08:46:32", DateTimeFormatter.ISO_LOCAL_DATE_TIME);

        // 自定义格式
        DateTimeFormatter dtf1 = DateTimeFormatter.ofPattern("yyyy/MM/dd");
        // 2020-05-30
        LocalDate localDate3 = LocalDate.parse("2020/05/30", dtf1);

        DateTimeFormatter dtf2 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        // 2020-05-30T08:55:13
        LocalDateTime localDateTime2 = LocalDateTime.parse("2020-05-30 08:55:13", dtf2);

4, 格式化时间

        LocalDateTime localDateTime = LocalDateTime.now();                             // 2020-07-08T08:59:50.152
        // 预置格式
        String s1 = localDateTime.format(DateTimeFormatter.BASIC_ISO_DATE);            // 20200708
        String s2 = localDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE);            // 2020-07-08
        String s3 = localDateTime.format(DateTimeFormatter.ISO_LOCAL_TIME);            // 08:59:50.152
        String s4 = localDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME);       // 2020-07-08T08:59:50.152
        // 自定义格式
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        String s5 = localDateTime.format(dtf);                                         // 2020-07-08 08:59:50

5, 时间计算

        LocalDateTime localDateTime = LocalDateTime.now();                             // 2020-07-08T09:11:51.902

        LocalDateTime localDateTime1 = localDateTime.plusDays(1);                      // 2020-07-09T09:11:51.902
        LocalDateTime localDateTime2 = localDateTime.plus(2, ChronoUnit.DAYS);  // 2020-07-10T09:11:51.902

        LocalDateTime localDateTime3 = localDateTime.minusDays(1);                     // 2020-07-07T09:11:51.902

        LocalDateTime localDateTime4 = localDateTime.plusYears(1);                     // 2021-07-08T09:11:51.902
        LocalDateTime localDateTime5 = localDateTime.plusMonths(1);                    // 2020-08-08T09:11:51.902

        LocalDateTime localDateTime6 = localDateTime.plusHours(1);                     // 2020-07-08T10:11:51.902
        LocalDateTime localDateTime7 = localDateTime.plusMinutes(1);                   // 2020-07-08T09:12:51.902
        LocalDateTime localDateTime8 = localDateTime.plusSeconds(1);                   // 2020-07-08T09:11:52.902

6, 时间工具类

package com.dosrain.shunc.trial.date;

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

public class DateUtil {

    /**
     * Date 转换为  LocalDate
     *
     * @param date
     * @return
     */
    public static LocalDate date2LocalDate(Date date) {
        Instant instant = date.toInstant();
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
        return localDateTime.toLocalDate();
    }

    /**
     * LocalDate 转换为 Date
     *
     * @param localDate
     * @return
     */
    public static Date localDate2Date(LocalDate localDate) {
        Instant instant = localDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant();
        return Date.from(instant);
    }

    /**
     * Date 转换为  LocalDateTime
     *
     * @param date
     * @return
     */
    public static LocalDateTime date2LocalDateTime(Date date) {
        Instant instant = date.toInstant();
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
        return localDateTime;
    }

    /**
     * LocalDateTime 转换为 Date
     *
     * @param localDateTime
     * @return
     */
    public static Date localDateTime2Date(LocalDateTime localDateTime) {
        Instant instant = localDateTime.atZone(ZoneId.systemDefault()).toInstant();
        return Date.from(instant);
    }

    /**
     * 格式化日期类型为字符串(LocalDate粒度)
     *
     * @param date
     * @param pattern
     * @return
     */
    public static String formatDate(Date date, String pattern) {
        Instant instant = date.toInstant();
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
        LocalDate localDate = localDateTime.toLocalDate();
        return localDate.format(DateTimeFormatter.ofPattern(pattern));
    }

    /**
     * 解析字符串为日期类型(LocalDate粒度)
     *
     * @param dateString
     * @param pattern
     * @return
     */
    public static Date parseDate(String dateString, String pattern) {
        LocalDate localDate = LocalDate.parse(dateString, DateTimeFormatter.ofPattern(pattern));
        Instant instant = localDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant();
        return Date.from(instant);
    }
    /**
     * 格式化日期类型为字符串(LocalDateTime粒度)
     *
     * @param date
     * @param pattern
     * @return
     */
    public static String formatDateTime(Date date, String pattern) {
        Instant instant = date.toInstant();
        LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
        return localDateTime.format(DateTimeFormatter.ofPattern(pattern));
    }

    /**
     * 解析字符串为日期类型(LocalDateTime粒度)
     *
     * @param dateString
     * @param pattern
     * @return
     */
    public static Date parseDateTime(String dateString, String pattern) {
        LocalDateTime localDateTime = LocalDateTime.parse(dateString, DateTimeFormatter.ofPattern(pattern));
        Instant instant = localDateTime.atZone(ZoneId.systemDefault()).toInstant();
        return Date.from(instant);
    }

    /**
     * 取得指定日期所在周的周一LocalDate类型
     *
     * @param localDate
     * @return
     */
    public static LocalDate getThisWeekMonday(LocalDate localDate) {
        localDate = localDate.plusDays(1 - localDate.getDayOfWeek().getValue());
        return localDate;
    }

    /**
     * 取得上周一的日期字符串
     *
     * @param pattern
     * @return
     */
    public static String getLastWeekMonday(String pattern) {
        LocalDate localDate = LocalDate.now();
        localDate = localDate.minusDays(7);
        localDate = getThisWeekMonday(localDate);
        return localDate.format(DateTimeFormatter.ofPattern(pattern));
    }

    /**
     * 取得上月1日的日期字符
     *
     * @param pattern
     * @return
     */
    public static String getLastMonthFirstDay(String pattern) {
        LocalDate localDate = LocalDate.now();
        localDate = localDate.minusMonths(1);
        localDate = localDate.minusDays(localDate.getDayOfMonth() -1);
        return localDate.format(DateTimeFormatter.ofPattern(pattern));
    }


    public static void main(String[] args) {
        System.out.println(DateUtil.formatDate(new Date(), "yyyy-MM-dd"));
        System.out.println(DateUtil.parseDate("2021-08-12", "yyyy-MM-dd"));

        System.out.println(DateUtil.formatDateTime(new Date(), "yyyy-MM-dd HH:mm:ss"));
        System.out.println(DateUtil.parseDateTime("2021-08-12 09:52:03", "yyyy-MM-dd HH:mm:ss"));
        System.out.println(DateUtil.getThisWeekMonday(LocalDate.now()));
        System.out.println(DateUtil.getLastWeekMonday("yyyy-MM-dd"));
        System.out.println(DateUtil.getLastMonthFirstDay("yyyy-MM-dd"));

    }
}

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