12. Java8-日期API-LocalDate

今天药忘吃喽~ 2022-02-02 01:41 297阅读 0赞

> LocalDate 是Java8 中用于表示日期的时间类, 只表示年月日.

package org.zongf.learn.java8.date;
    
    import org.junit.Test;
    import java.time.*;
    import java.time.format.DateTimeFormatter;
    import java.time.temporal.*;
    
    /** * @Description: 测试LocalDate 常用API * @author: zongf * @date: 2018-06-29 13:19 */
    public class TestLocalDate { 
    
        //测试构造方法
        @Test
        public void constructor(){ 
    
            // 获取当前日期
            LocalDate ld1 = LocalDate.now();    //2018-06-29
    
            // 根据指定年月日获取日期
            LocalDate ld2 = LocalDate.of(2018, 06, 29);
    
            // 根据字符串解析日期
            LocalDate ld5 = LocalDate.parse("2018-06-29");
    
            // 指定日期格式解析字符串
            LocalDate ld6 = LocalDate.parse("29/06/2018", DateTimeFormatter.ofPattern("dd/MM/yyyy"));
    
            // 获取某个时区的日期,下午13:36 测试时比北京日期晚一天
            LocalDate ld7 = LocalDate.now(ZoneId.of("US/Pacific"));  // 2018-06-28
    
            // 获取某年的第几天的日期
            LocalDate ld4 = LocalDate.ofYearDay(2018, 100);
    
            // 获取Unix 元年(1970-01-01) 之后的第几天
            LocalDate ld3 = LocalDate.ofEpochDay(100);
    
    
            System.out.println(ld1);
            System.out.println(ld2);
            System.out.println(ld3);
            System.out.println(ld4);
            System.out.println(ld5);
            System.out.println(ld6);
            System.out.println(ld7);
    
        }
    
        // 测试常用get 方法
        @Test
        public void test_get(){ 
    
            LocalDate today = LocalDate.now();
    
            System.out.println("年:" + today.getYear());
            System.out.println("月:" + today.getMonthValue());
            System.out.println("日:" + today.getDayOfMonth());
            System.out.println("月份(英文):" + today.getMonth());
            System.out.println("星期(英文):" + today.getDayOfWeek());
    
            System.out.println("当月第几天:" + today.getDayOfMonth());
            System.out.println("当年第几天：" + today.getDayOfYear());
            System.out.println("Unix元年后第几天:" + today.toEpochDay());
            System.out.println();
    
            System.out.println("当月总天数:" + today.lengthOfMonth());
            System.out.println("当年总天数:" + today.lengthOfYear());
            System.out.println("是否是闰年:" + today.isLeapYear());
            System.out.println();
    
            // 更通用的方法
            System.out.println("年:" + today.get(ChronoField.YEAR));
            System.out.println("月:" + today.get(ChronoField.MONTH_OF_YEAR));
            System.out.println("日:" + today.get(ChronoField.DAY_OF_MONTH));
            System.out.println("本周第几天(数字):" + today.get(ChronoField.DAY_OF_WEEK));
            System.out.println("当年第几天:" + today.get(ChronoField.DAY_OF_YEAR));
            System.out.println("当月第几天%7:" + today.get(ChronoField.ALIGNED_DAY_OF_WEEK_IN_MONTH));
            System.out.println("当年第几天%7" + today.get(ChronoField.ALIGNED_DAY_OF_WEEK_IN_YEAR));
            System.out.println("当月第几周:" + today.get(ChronoField.ALIGNED_WEEK_OF_MONTH));
            System.out.println("当年第几周:" + today.get(ChronoField.ALIGNED_WEEK_OF_YEAR));
            System.out.println("Unix元年后第几天:" + today.getLong(ChronoField.EPOCH_DAY));
    
        }
    
        // 测试常用日期运算
        @Test
        public void test_plus(){ 
    
            LocalDate today = LocalDate.now();
    
            System.out.println("当前日期:" + today);
            System.out.println();
    
            // 使用plus 获取当前日期
            System.out.println("三天后日期:" + today.plusDays(3));
            System.out.println("三月后日期:" + today.plusMonths(3));
            System.out.println("三周后日期:" + today.plusWeeks(3));
            System.out.println("三年后日期:" + today.plusYears(3));
            System.out.println();
    
            System.out.println("三天前日期:" + today.minusDays(3));
            System.out.println("三月前日期:" + today.minusMonths(3));
            System.out.println("三周前日期:" + today.minusWeeks(3));
            System.out.println("三年前日期:" + today.minusYears(3));
            System.out.println();
    
            System.out.println("三天前日期:" + today.minus(Period.ofDays(3)));
            System.out.println("三月前日期:" + today.minus(Period.ofMonths(3)));
            System.out.println("三年前日期:" + today.minus(Period.ofYears(3)));
            System.out.println("三周前日期:" + today.minus(Period.ofWeeks(3)));
            System.out.println("三年零三个月又三天前日期:" + today.minus(Period.of(3,3,3)));
            System.out.println();
    
            System.out.println("三天后日期:" + today.plus(Period.ofDays(3)));
            System.out.println("三月后日期:" + today.plus(Period.ofMonths(3)));
            System.out.println("三年后日期:" + today.plus(Period.ofYears(3)));
            System.out.println("三周后日期:" + today.plus(Period.ofWeeks(3)));
            System.out.println("三年零三个月又三天后日期:" + today.plus(Period.of(3,3,3)));
        }
    
        // 测试日期比较
        @Test
        public void test_compare(){ 
            LocalDate today = LocalDate.now();
            LocalDate tomorrow = LocalDate.now().plusYears(1);
            LocalDate yesterday = LocalDate.now().minusYears(1);
    
            System.out.println(today.isBefore(tomorrow));
            System.out.println(today.isAfter(tomorrow));
            System.out.println(today.compareTo(yesterday));
            System.out.println(yesterday.compareTo(tomorrow));
    
        }
    
        // 使用with 方法获取和当前日期相关的日期
        @Test
        public void with(){ 
            LocalDate ld = LocalDate.now();
            System.out.println("当期日期:" + ld);
            System.out.println("替换年为2020:" + ld.withYear(2020));
            System.out.println("替换月为5:" + ld.withMonth(5));
            System.out.println("替换日为15:" + ld.withDayOfMonth(15));
            System.out.println("替换为当年第100天:" + ld.withDayOfYear(100));
            System.out.println();
    
            System.out.println("获取当月第一天:" + ld.with(TemporalAdjusters.firstDayOfMonth()));
            System.out.println("获取当年第一天:" + ld.with(TemporalAdjusters.firstDayOfYear()));
            System.out.println("获取下月第一天:" + ld.with(TemporalAdjusters.firstDayOfNextMonth()));
            System.out.println("获取来年第一天:" + ld.with(TemporalAdjusters.firstDayOfNextYear()));
            System.out.println("获取当年最后一天:" + ld.with(TemporalAdjusters.lastDayOfYear()));
            System.out.println("获取当月最后一天:" + ld.with(TemporalAdjusters.lastDayOfMonth()));
            System.out.println("获取当月第一个周五:" + ld.with(TemporalAdjusters.firstInMonth(DayOfWeek.FRIDAY)));
            System.out.println("获取当月最后一个周五:" + ld.with(TemporalAdjusters.lastInMonth(DayOfWeek.FRIDAY)));
            System.out.println("获取当月下一个周五(不包括今天):" + ld.with(TemporalAdjusters.next(DayOfWeek.FRIDAY)));
            System.out.println("获取当月下一个周五(包括今天):" + ld.with(TemporalAdjusters.nextOrSame(DayOfWeek.FRIDAY)));
            System.out.println("获取当月上一个周五(不包括今天):" + ld.with(TemporalAdjusters.previous(DayOfWeek.FRIDAY)));
            System.out.println("获取当月上一个周五(包括今天):" + ld.with(TemporalAdjusters.previousOrSame(DayOfWeek.FRIDAY)));
            // 自定义TemporalAdjuster 对象，实现下一个工作日
            TemporalAdjuster nextWorkingDay = TemporalAdjusters.ofDateAdjuster(
                    temporal -> { 
                        DayOfWeek dow = DayOfWeek.of(temporal.get(ChronoField.DAY_OF_WEEK));
                        int dayToAdd = 1;
                        if(dow==DayOfWeek.FRIDAY) dayToAdd = 3;
                        if(dow==DayOfWeek.SATURDAY) dayToAdd = 2;
                        return temporal.plus(dayToAdd, ChronoUnit.DAYS);
                    }
            );
            System.out.println("获取下一个工作日:" + ld.with(nextWorkingDay));
        }
    
        // 计算两个时间之间的差
        @Test
        public void test_until(){ 
            LocalDate ld1 = LocalDate.of(2005, 9, 30);
            LocalDate ld2 = LocalDate.of(2018, 3, 10);
    
            System.out.println("日期间隔-总年数:" + ld1.until(ld2, ChronoUnit.YEARS));
            System.out.println("日期间隔-总月数:" + ld1.until(ld2, ChronoUnit.MONTHS));
            System.out.println("日期间隔-总天数:" + ld1.until(ld2, ChronoUnit.DAYS));
            System.out.println("时间间隔-多少个十年:" + ld1.until(ld2, ChronoUnit.DECADES));
        }
    
        // 测试日期直接的间隔
        @Test
        public void test_between(){ 
    
            LocalDate ld1 = LocalDate.of(2015, 8, 28);
            LocalDate ld2 = LocalDate.of(2018, 3, 10);
    
            // 计算日期之间相差总时间数
    
            Period period = Period.between(ld1, ld2);
    // Period period = ld1.until(ld2); // 等价于
            System.out.println("日期间隔:" + period);
            System.out.println("日期间隔-年:" + period.getYears());
            System.out.println("日期间隔-月:" + period.getMonths());
            System.out.println("日期间隔-日:" + period.getDays());
            System.out.println("日期间隔-总月数:" + period.toTotalMonths());
    
            System.out.println("日期间隔-年:" + period.get(ChronoUnit.DAYS));
            System.out.println("日期间隔-月:" + period.get(ChronoUnit.MONTHS));
            System.out.println("日期间隔-日:" + period.get(ChronoUnit.YEARS));
    
            System.out.println("日期间隔是否是负数:" + period.isNegative());
            System.out.println("日期间隔是否是0:" + period.isZero());
    
        }
    
        // 测试日期转换
        @Test
        public void test_converter(){ 
    
            LocalDate ld = LocalDate.now();
    
            // 获取当天开始时间
            LocalDateTime ldt1 = ld.atStartOfDay();
            System.out.println(ldt1);
    
            // 获取指定时区当天开始时间
            ZonedDateTime zonedDateTime = ld.atStartOfDay(ZoneId.of("US/Pacific"));
            System.out.println(zonedDateTime); //2018-06-30T00:00-07:00[US/Pacific]
    
            // 获取当天具体时间
            LocalDateTime ldt2 = ld.atTime(8, 20, 30);
            System.out.println(ldt2);
    
            // 获取当天具体时间
            LocalDateTime ldt3 = ld.atTime(LocalTime.of(8, 20, 30));
            System.out.println(ldt3);
    
        }
    
    
    }