Detailed analysis of Java's JDK8 time-related classes

JDK8 time-related classes

JDK8 time class class name	effect
ZoneId	Time zone
Instant	timestamp
ZoneDateTime	time with time zone
DateTimeFormatter	Formatting and parsing for time
LocalDate	year month day
LocalTime	Minutes and seconds
LocalDateTime	Year, month, day, hour, minute, second
Duration	time interval (sec, nano, sec)
Period	time interval (year, month, day)
ChronoUnit	time interval (all units)

4.1 ZoneId time zone

/*
        static Set<string> getAvailableZoneIds() 获取Java中支持的所有时区
        static ZoneId systemDefault() 获取系统默认时区
        static Zoneld of(string zoneld) 获取一个指定时区
        */
​
//1.获取所有的时区名称
Set<String> zoneIds = ZoneId.getAvailableZoneIds();
System.out.println(zoneIds.size());//600
System.out.println(zoneIds);// Asia/Shanghai
​
//2.获取当前系统的默认时区
ZoneId zoneId = ZoneId.systemDefault();
System.out.println(zoneId);//Asia/Shanghai
​
//3.获取指定的时区
ZoneId zoneId1 = ZoneId.of("Asia/Pontianak");
System.out.println(zoneId1);//Asia/Pontianak

4.2 Instant timestamp

/*
            static Instant now() 获取当前时间的Instant对象(标准时间)
            static Instant ofXxxx(long epochMilli) 根据(秒/毫秒/纳秒)获取Instant对象
            ZonedDateTime atZone(ZoneIdzone) 指定时区
            boolean isxxx(Instant otherInstant) 判断系列的方法
            Instant minusXxx(long millisToSubtract) 减少时间系列的方法
            Instant plusXxx(long millisToSubtract) 增加时间系列的方法
        */
//1.获取当前时间的Instant对象(标准时间)
Instant now = Instant.now();
System.out.println(now);
​
//2.根据(秒/毫秒/纳秒)获取Instant对象
Instant instant1 = Instant.ofEpochMilli(0L);
System.out.println(instant1);//1970-01-01T00:00:00z
​
Instant instant2 = Instant.ofEpochSecond(1L);
System.out.println(instant2);//1970-01-01T00:00:01Z
​
Instant instant3 = Instant.ofEpochSecond(1L, 1000000000L);
System.out.println(instant3);//1970-01-01T00:00:027
​
//3. 指定时区
ZonedDateTime time = Instant.now().atZone(ZoneId.of("Asia/Shanghai"));
System.out.println(time);
​
​
//4.isXxx 判断
Instant instant4=Instant.ofEpochMilli(0L);
Instant instant5 =Instant.ofEpochMilli(1000L);
​
//5.用于时间的判断
//isBefore:判断调用者代表的时间是否在参数表示时间的前面
boolean result1=instant4.isBefore(instant5);
System.out.println(result1);//true
​
//isAfter:判断调用者代表的时间是否在参数表示时间的后面
boolean result2 = instant4.isAfter(instant5);
System.out.println(result2);//false
​
//6.Instant minusXxx(long millisToSubtract) 减少时间系列的方法
Instant instant6 =Instant.ofEpochMilli(3000L);
System.out.println(instant6);//1970-01-01T00:00:03Z
​
Instant instant7 =instant6.minusSeconds(1);
System.out.println(instant7);//1970-01-01T00:00:02Z
​

4.3 ZoneDateTime time with time zone

/*
            static ZonedDateTime now() 获取当前时间的ZonedDateTime对象
            static ZonedDateTime ofXxxx(。。。) 获取指定时间的ZonedDateTime对象
            ZonedDateTime withXxx(时间) 修改时间系列的方法
            ZonedDateTime minusXxx(时间) 减少时间系列的方法
            ZonedDateTime plusXxx(时间) 增加时间系列的方法
         */
//1.获取当前时间对象(带时区)
ZonedDateTime now = ZonedDateTime.now();
System.out.println(now);
​
//2.获取指定的时间对象(带时区)1/年月日时分秒纳秒方式指定
ZonedDateTime time1 = ZonedDateTime.of(2023, 10, 1,
                                       11, 12, 12, 0, ZoneId.of("Asia/Shanghai"));
System.out.println(time1);
​
//通过Instant + 时区的方式指定获取时间对象
Instant instant = Instant.ofEpochMilli(0L);
ZoneId zoneId = ZoneId.of("Asia/Shanghai");
ZonedDateTime time2 = ZonedDateTime.ofInstant(instant, zoneId);
System.out.println(time2);
​
​
//3.withXxx 修改时间系列的方法
ZonedDateTime time3 = time2.withYear(2000);
System.out.println(time3);
​
//4. 减少时间
ZonedDateTime time4 = time3.minusYears(1);
System.out.println(time4);
​
//5.增加时间
ZonedDateTime time5 = time4.plusYears(1);
System.out.println(time5);

4.4DateTimeFormatter is used for time formatting and parsing

/*
            static DateTimeFormatter ofPattern(格式) 获取格式对象
            String format(时间对象) 按照指定方式格式化
        */
//获取时间对象
ZonedDateTime time = Instant.now().atZone(ZoneId.of("Asia/Shanghai"));
​
// 解析/格式化器
DateTimeFormatter dtf1=DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm;ss EE a");
// 格式化
System.out.println(dtf1.format(time));

4.5LocalDate year, month, day

//1.获取当前时间的日历对象(包含 年月日)
LocalDate nowDate = LocalDate.now();
//System.out.println("今天的日期:" + nowDate);
//2.获取指定的时间的日历对象
LocalDate ldDate = LocalDate.of(2023, 1, 1);
System.out.println("指定日期:" + ldDate);
​
System.out.println("=============================");
​
//3.get系列方法获取日历中的每一个属性值//获取年
int year = ldDate.getYear();
System.out.println("year: " + year);
//获取月//方式一:
Month m = ldDate.getMonth();
System.out.println(m);
System.out.println(m.getValue());
​
//方式二:
int month = ldDate.getMonthValue();
System.out.println("month: " + month);
​
​
//获取日
int day = ldDate.getDayOfMonth();
System.out.println("day:" + day);
​
//获取一年的第几天
int dayofYear = ldDate.getDayOfYear();
System.out.println("dayOfYear:" + dayofYear);
​
//获取星期
DayOfWeek dayOfWeek = ldDate.getDayOfWeek();
System.out.println(dayOfWeek);
System.out.println(dayOfWeek.getValue());
​
//is开头的方法表示判断
System.out.println(ldDate.isBefore(ldDate));
System.out.println(ldDate.isAfter(ldDate));
​
//with开头的方法表示修改，只能修改年月日
LocalDate withLocalDate = ldDate.withYear(2000);
System.out.println(withLocalDate);
​
//minus开头的方法表示减少，只能减少年月日
LocalDate minusLocalDate = ldDate.minusYears(1);
System.out.println(minusLocalDate);
​
​
//plus开头的方法表示增加，只能增加年月日
LocalDate plusLocalDate = ldDate.plusDays(1);
System.out.println(plusLocalDate);
​
//-------------
// 判断今天是否是你的生日
LocalDate birDate = LocalDate.of(2000, 1, 1);
LocalDate nowDate1 = LocalDate.now();
​
MonthDay birMd = MonthDay.of(birDate.getMonthValue(), birDate.getDayOfMonth());
MonthDay nowMd = MonthDay.from(nowDate1);
​
System.out.println("今天是你的生日吗? " + birMd.equals(nowMd));//今天是你的生日吗?

4.6 LocalTime hour, minute, second

// 获取本地时间的日历对象。(包含 时分秒)
LocalTime nowTime = LocalTime.now();
System.out.println("今天的时间:" + nowTime);
​
int hour = nowTime.getHour();//时
System.out.println("hour: " + hour);
​
int minute = nowTime.getMinute();//分
System.out.println("minute: " + minute);
​
int second = nowTime.getSecond();//秒
System.out.println("second:" + second);
​
int nano = nowTime.getNano();//纳秒
System.out.println("nano:" + nano);
System.out.println("------------------------------------");
System.out.println(LocalTime.of(8, 20));//时分
System.out.println(LocalTime.of(8, 20, 30));//时分秒
System.out.println(LocalTime.of(8, 20, 30, 150));//时分秒纳秒
LocalTime mTime = LocalTime.of(8, 20, 30, 150);
​
//is系列的方法
System.out.println(nowTime.isBefore(mTime));
System.out.println(nowTime.isAfter(mTime));
​
//with系列的方法，只能修改时、分、秒
System.out.println(nowTime.withHour(10));
​
//plus系列的方法，只能修改时、分、秒
System.out.println(nowTime.plusHours(10));

4.7 LocalDateTime year, month, day, hour, minute, second

// 当前时间的的日历对象(包含年月日时分秒)
LocalDateTime nowDateTime = LocalDateTime.now();
​
System.out.println("今天是:" + nowDateTime);//今天是：
System.out.println(nowDateTime.getYear());//年
System.out.println(nowDateTime.getMonthValue());//月
System.out.println(nowDateTime.getDayOfMonth());//日
System.out.println(nowDateTime.getHour());//时
System.out.println(nowDateTime.getMinute());//分
System.out.println(nowDateTime.getSecond());//秒
System.out.println(nowDateTime.getNano());//纳秒
// 日:当年的第几天
System.out.println("dayofYear:" + nowDateTime.getDayOfYear());
//星期
System.out.println(nowDateTime.getDayOfWeek());
System.out.println(nowDateTime.getDayOfWeek().getValue());
//月份
System.out.println(nowDateTime.getMonth());
System.out.println(nowDateTime.getMonth().getValue());
​
LocalDate ld = nowDateTime.toLocalDate();
System.out.println(ld);
​
LocalTime lt = nowDateTime.toLocalTime();
System.out.println(lt.getHour());
System.out.println(lt.getMinute());
System.out.println(lt.getSecond());

4.8 Duration time interval (seconds, nanometers, seconds)

// 本地日期时间对象。
LocalDateTime today = LocalDateTime.now();
System.out.println(today);
​
// 出生的日期时间对象
LocalDateTime birthDate = LocalDateTime.of(2000, 1, 1, 0, 0, 0);
System.out.println(birthDate);
​
Duration duration = Duration.between(birthDate, today);//第二个参数减第一个参数
System.out.println("相差的时间间隔对象:" + duration);
​
System.out.println("============================================");
System.out.println(duration.toDays());//两个时间差的天数
System.out.println(duration.toHours());//两个时间差的小时数
System.out.println(duration.toMinutes());//两个时间差的分钟数
System.out.println(duration.toMillis());//两个时间差的毫秒数
System.out.println(duration.toNanos());//两个时间差的纳秒数

4.9 Period time interval (year, month, day)

// 当前本地 年月日
LocalDate today = LocalDate.now();
System.out.println(today);
​
// 生日的 年月日
LocalDate birthDate = LocalDate.of(2000, 1, 1);
System.out.println(birthDate);
​
Period period = Period.between(birthDate, today);//第二个参数减第一个参数
​
System.out.println("相差的时间间隔对象:" + period);
System.out.println(period.getYears());
System.out.println(period.getMonths());
System.out.println(period.getDays());
​
System.out.println(period.toTotalMonths());

4.10 ChronoUnit time interval (all units)

// 当前时间
LocalDateTime today = LocalDateTime.now();
System.out.println(today);
// 生日时间
LocalDateTime birthDate = LocalDateTime.of(2000, 1, 1,0, 0, 0);
System.out.println(birthDate);
​
System.out.println("相差的年数:" + ChronoUnit.YEARS.between(birthDate, today));
System.out.println("相差的月数:" + ChronoUnit.MONTHS.between(birthDate, today));
System.out.println("相差的周数:" + ChronoUnit.WEEKS.between(birthDate, today));
System.out.println("相差的天数:" + ChronoUnit.DAYS.between(birthDate, today));
System.out.println("相差的时数:" + ChronoUnit.HOURS.between(birthDate, today));
System.out.println("相差的分数:" + ChronoUnit.MINUTES.between(birthDate, today));
System.out.println("相差的秒数:" + ChronoUnit.SECONDS.between(birthDate, today));
System.out.println("相差的毫秒数:" + ChronoUnit.MILLIS.between(birthDate, today));
System.out.println("相差的微秒数:" + ChronoUnit.MICROS.between(birthDate, today));
System.out.println("相差的纳秒数:" + ChronoUnit.NANOS.between(birthDate, today));
System.out.println("相差的半天数:" + ChronoUnit.HALF_DAYS.between(birthDate, today));
System.out.println("相差的十年数:" + ChronoUnit.DECADES.between(birthDate, today));
System.out.println("相差的世纪(百年)数:" + ChronoUnit.CENTURIES.between(birthDate, today));
System.out.println("相差的千年数:" + ChronoUnit.MILLENNIA.between(birthDate, today));
System.out.println("相差的纪元数:" + ChronoUnit.ERAS.between(birthDate, today));