JDK1.8时间工具类

朱雀 2023-10-10 11:54 143阅读 0赞

### JDK1.8时间工具类 ###

一、特点：比起Date类和Calendar类，jdk1.8的时间类更全面、线程安全、可修改

二、JDK1.8各时间类特点及应用

2.1、LocalDate类

//取当前日期
    LocalDate today=LocalDate.now();
    System.out.println("today = " + today);

输出：today = 2020-11-24

LocalDate ld = LocalDate.now();
     System.out.println(ld);
     int ofYear = ld.getDayOfYear();
     Date date = new Date();
     GregorianCalendar calendar = new GregorianCalendar();
    // 设置当前日期date 
    calendar.setTime(date);
     calendar.add(Calendar.YEAR,1);// 日期往后，增加一年，整数往后推，负数往前移动
    //获取一年后的日期
     date=calendar.getTime();
    // 设置日期格式
     SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
     System.out.println("一年后今天的日期："+sdf.format(date));
     System.out.println("当前一年中的第几天："+ofYear);

一年后今天的日期：2021-12-01
    当前一年中的第几天：336

//取当前日期
     LocalDate today=LocalDate.now();
     //获取当前是一周的第几天
     int dayOfWeek = today.getDayOfWeek().getValue();
     System.out.println("dayOfWeek = " + dayOfWeek);
     //获取当前日
     int dayOfMonth = today.getDayOfMonth();
     System.out.println("dayOfMonth = " + dayOfMonth);
     //获取当前是一年中的第几天
     int dayOfYear = today.getDayOfYear();
     System.out.println("dayOfYear = " + dayOfYear);
     //获取当前月
     int monthValue = today.getMonthValue();
     System.out.println("monthValue = " + monthValue);
     //获取当前年
     int year = today.getYear();
     System.out.println("year = " + year);

输出：
    dayOfWeek = 2
    dayOfMonth = 24
    dayOfYear = 329
    monthValue = 11
    year = 2020

//根据年月日取日期,12月就是12月，月份不需要像date和calendar类0-11
     LocalDate myDate = LocalDate.of(2020, 11, 11);
     System.out.println("myDate = " + myDate);

输出：myDate = 2020-11-11

//根据字符串取1：（必须严格按照格式:yyyy-MM-dd）
    LocalDate parseStr1 = LocalDate.parse("2020-11-24");
    System.out.println("parseStr1 = " + parseStr1);

输出：parseStr1 = 2020-11-24

//根据字符串取2：（自定义格式）
    LocalDate parseStr2 = LocalDate.parse("2020/08/02", DateTimeFormatter.ofPattern("yyyy/MM/dd"));
    System.out.println("parseStr2 = " + parseStr2);

输出：parseStr2 = 2020-08-02

//取本月第一天
    LocalDate firstDayOfMonth = today.with(TemporalAdjusters.firstDayOfMonth());
    System.out.println("firstDayOfMonth = " + firstDayOfMonth);

输出：firstDayOfMonth = 2020-11-01

//取本月第2天：
    LocalDate secondDayOfMonth = today.withDayOfMonth(2);
    System.out.println("secondDayOfMonth = " + secondDayOfMonth);

输出：secondDayOfMonth = 2020-11-02

//取本月最后一天
    LocalDate lastDayOfMonth = today.with(TemporalAdjusters.lastDayOfMonth());
    System.out.println("lastDayOfMonth = " + lastDayOfMonth);

输出：lastDayOfMonth = 2020-11-30

//取下一天
    LocalDate tomorrow = lastDayOfMonth.plusDays(1);
    System.out.println("tomorrow = " + tomorrow);

输出：tomorrow = 2020-12-01

//取2020年11月第一个周一
    LocalDate firstMondayOf2020 = LocalDate.parse("2020-11-01").with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
    System.out.println("firstMondayOf2020 = " + firstMondayOf2020);

输出：firstMondayOf2020 = 2020-11-02

//几个使用方法
    LocalDate today = LocalDate.now();
    
    //判断 today 是否为闰年
    boolean isLeapYear = today.isLeapYear();
    System.out.println("isLeapYear = " + isLeapYear);
    
    //获取 today 是该年的第几季度
    int quarterOfYear = today.get(IsoFields.QUARTER_OF_YEAR);
    System.out.println("quarterOfYear = " + quarterOfYear);
    
    //获取 today 是该季度的第几天
    int daysOfQuarter = today.get(IsoFields.DAY_OF_QUARTER);
    System.out.println("daysOfQuarter = " + daysOfQuarter);

输出：
    isLeapYear = true
    quarterOfYear = 4
    daysOfQuarter = 55

2.2、LocalTime类

//获取当前时间(带有毫秒)
    LocalTime timeMills = LocalTime.now();
    System.out.println("timeMills = " + timeMills);
    //在timeMills的基础上获取不带毫秒的time
    //nanoSecond纳秒,十亿分之一秒
    LocalTime time1 = timeMills.withNano(0);
    System.out.println("time1 = " + time1);
    
    //设置并得到时间对象
    LocalTime time2 = LocalTime.of(12, 00, 00);
    System.out.println("time2 = " + time2);
    
    //解析时间字符串
    LocalTime parseStr1 = LocalTime.parse("12:30:00");
    System.out.println("parseStr1 = " + parseStr1);
    LocalTime parseStr2 = LocalTime.parse("12时30分00秒", DateTimeFormatter.ofPattern("HH时mm分ss秒"));
    System.out.println("parseStr2 = " + parseStr2);
    
    //获取一天的第多少秒的时间对象
    LocalTime time3 = LocalTime.ofSecondOfDay(18 * 60 * 60 + 60 * 30);
    System.out.println("time3 = " + time3);
    
    //MIN、MAX、 NOON、 MIDNIGHT
    //MIN和MIDNIGHT都是00:00，意味一天的开始
    //NOON是中午12:00，意味着半天
    //MAX是23:59:59.999999999，意味着一天的结束
    System.out.println("MIN = " + LocalTime.MIN);
    System.out.println("MIDNIGHT = " + LocalTime.MIDNIGHT);
    System.out.println("NOON = " + LocalTime.NOON);
    System.out.println("MAX = " + LocalTime.MAX);

输出：
    timeMills = 22:58:55.326
    time1 = 22:58:55
    time2 = 12:00
    parseStr1 = 12:30
    parseStr2 = 12:30
    time3 = 18:30
    MIN = 00:00
    MIDNIGHT = 00:00
    NOON = 12:00
    MAX = 23:59:59.999999999

//获取当前时间(带有毫秒)
    LocalTime timeMills = LocalTime.now();
    System.out.println("timeMills = " + timeMills);
    //在timeMills的基础上获取不带毫秒的time
    //nanoSecond纳秒,十亿分之一秒
    LocalTime time = timeMills.withNano(0);
    System.out.println("time = " + time);
    
    //获取时
    int hour = time.getHour();
    System.out.println("hour = " + hour);
    //获取分
    int minute = time.getMinute();
    System.out.println("minute = " + minute);
    //获取秒
    int second = time.getSecond();
    System.out.println("second = " + second);
    
    //下班时间
    LocalTime workOver = LocalTime.of(18, 30, 00);
    
    //睡觉时间
    LocalTime sleepTime = LocalTime.of(23, 30, 00);
    
    //判断现在是否是下班时间
    boolean after = time.isAfter(workOver);
    System.out.println("after = " + after);
    //判断现在是否是睡觉时间
    boolean before = time.isBefore(sleepTime);
    System.out.println("before = " + before);
    
    //现在和下班时间比较
    int i = time.compareTo(workOver);
    System.out.println("i = " + i);
    //现在和睡觉时间比较
    int j = time.compareTo(sleepTime);
    System.out.println("j = " + j);
    
    //获取离现在1个半小时的时间
    LocalTime time2 = time.plusHours(1).plusMinutes(30);
    System.out.println("time2 = " + time2);

输出：
    timeMills = 23:11:22.379
    time = 23:11:22
    hour = 23
    minute = 11
    second = 22
    after = true
    before = true
    i = 1
    j = -1
    time2 = 00:41:22

2.3、LocalDateTime类

//LocalDateTime
    LocalDateTime dateTime=LocalDateTime.now();
    System.out.println("dateTime="+dateTime);
    		
    //获取年月日时分秒
    int year=dateTime.getYear();
    System.out.println("year="+year);
    int month=dateTime.getMonthValue();
    System.out.println("month="+month);
    int date=dateTime.getDayOfMonth();
    System.out.println("date="+date);
    int hour=dateTime.getHour();
    System.out.println("hour"+hour);
    int minute=dateTime.getMinute();
    System.out.println("minute="+minute);
    int second=dateTime.getSecond();
    System.out.println("second="+second);
    		
    //格式化时间
    LocalDateTime dateTime2=LocalDateTime.parse("2020-12-12 08:08:30.116", DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS"));
    System.out.println("dateTime2="+dateTime2);
    //打印dateTime2前五天、后一月
    System.out.println("dateTime2前五天"+dateTime2.plusDays(-5));
    System.out.println("dateTime2后一月"+dateTime2.plusMonths(1));
    		
    		
    //创建指定时间
    LocalDateTime dateTime3=LocalDateTime.of(2020, 11, 11, 11, 11,11,11);
    System.out.println("dateTime3="+dateTime3);
    //比较dateTime2和dateTime3
    System.out.println("dateTime2是否比dateTime3早："+dateTime2.isBefore(dateTime3));
    System.out.println("dateTime2是否比dateTime3晚："+dateTime2.isAfter(dateTime3));

输出:
    dateTime=2020-11-25T16:28:22.799
    year=2020
    month=11
    date=25
    hour16
    minute=28
    second=22
    dateTime2=2020-12-12T08:08:30.116
    dateTime2前五天2020-12-07T08:08:30.116
    dateTime2后一月2021-01-12T08:08:30.116
    dateTime3=2020-11-11T11:11:11.000000011
    dateTime2是否比dateTime3早：false
    dateTime2是否比dateTime3晚：true

2.4、Period、ChronoUnit 、Duration 类

1.  Period（具体相差的年月日）

//创建第一个日期对象(你的名字上映日期)
    LocalDate date1=LocalDate.of(2016, 12, 02);
    //创建第二个日期对象(天气之子上映日期)
    LocalDate date2=LocalDate.of(2019, 1, 01);
    Period period=Period.between(date1, date2);
    //打印两个日期相差
    System.out.println("相差年数:"+period.getYears()+"，相差月数:"+period.getMonths()+"，相差天数:"+period.getDays());

输出：
    相差年数:2，相差月数:0，相差天数:30

1.  ChronoUnit （日期周期单位的标准集合，也可以计算相差时分秒）

//创建第一个日期对象(你的名字上映日期)
    LocalDate date1=LocalDate.of(2016, 12, 02);
    //创建第二个日期对象(天气之子上映日期)
    LocalDate date2=LocalDate.of(2019, 1, 01);
    //打印两个日期相差
    System.out.println("相差年数:"+ChronoUnit.YEARS.between(date1, date2)+"，相差月数:"+ChronoUnit.MONTHS.between(date1, date2)+"，相差天数:"+ChronoUnit.DAYS.between(date1, date2));

输出：
    相差年数:2，相差月数:0，相差天数:30

*  ration (这个类以秒和纳秒为单位建模时间的数量或数量)

// 获取现在的时间戳
    Instant instant1 = Instant.now();
    // 获取离现在的30秒的时间戳
    Instant instant2 = instant1.plus(Duration.ofSeconds(30));
    System.out.println("增加之后的时间 : " + instant2);
    System.out.println("相差毫秒 : " + Duration.between(instant1, instant2).toMillis());
    System.out.println("相毫秒 : " + Duration.between(instant1, instant2).getSeconds());

输出：
    增加之后的时间 : 2020-11-25T08:45:38.312Z
    相差毫秒 : 30000
    相毫秒 : 30

4.总结  
Period–>LocalDate  
Duration–>LocalTime  
ChronoUnit–>LocalDatetime

2.5、Clock、ZonedDateTime、ZoneId(时区)类

1.  Clock(Clock时钟类用于获取当时的时间戳，或当前时区下的日期时间信息)

Clock clock1=Clock.systemUTC();
    System.out.println("当前时间戳:"+clock1.millis());
    Clock clock2=Clock.system(ZoneId.of("Asia/Shanghai"));
    System.out.println("亚洲上海此时的时间戳："+clock2.millis());
    Clock clock3=Clock.system(ZoneId.of("America/New_York"));
    System.out.println("美国纽约此时的时间戳："+clock2.millis());

输出：
    当前时间戳:1606294357632
    亚洲上海此时的时间戳：1606294357753
    美国纽约此时的时间戳：1606294357756

*  teTime(获取时间 和时区)

ZoneId zoneId= ZoneId.of("America/Los_Angeles");
    ZonedDateTime dateTime=ZonedDateTime.now(zoneId);
    System.out.println("美国洛杉矶此时的时间 : " + dateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS")));
    System.out.println("美国洛杉矶此时的时间 和时区: " + dateTime);

输出：
    美国洛杉矶此时的时间 : 2020-11-25 00:55:55.086
    美国洛杉矶此时的时间 和时区: 2020-11-25T00:55:55.086-08:00[America/Los_Angeles]

**参考博客一：https://blog.csdn.net/cauchy6317/article/details/99005855**  
**参考博客二：https://blog.csdn.net/cauchy6317/article/details/99298830**  
**参考博客三：https://www.cnblogs.com/pxblog/p/13453817.html**