JDK1.8 时间及格式化类

2020-04-03 22:44:17

针对 JDK1.8 以前的时间类设计的不足,JDK1.8 引入了 `java.time` 包来作为新的时间处理类。 下面为测试代码: ``` package test.demo; import org.junit.Test; import java.time.*; import java.time.format.DateTimeFormatter; import java.time.temporal.ChronoUnit; import java.util.Date; import java.util.TimeZone; /** * JDK 1.8 新增的日期时间及格式化类(线程安全) */ public class TestDate { /** * JDK 1.8 提供的线程安全的时间类 */ @Test public void testDate() { String separator = "========================"; // LocalDateTime 综合了 LocalDate 和 LocalTime 的方法。 // 获取当前日期 LocalDate nowDate = LocalDate.now(); System.out.println(nowDate); System.out.println(nowDate.getYear()); System.out.println(nowDate.getMonthValue()); System.out.println(nowDate.getMonth()); System.out.println(nowDate.getMonth().getValue()); System.out.println(nowDate.getDayOfMonth()); System.out.println(nowDate.getDayOfWeek()); System.out.println(nowDate.getDayOfWeek().getValue()); System.out.println(nowDate.getDayOfYear()); System.out.println(separator); // 获取当前时间 LocalTime nowTime = LocalTime.now(); System.out.println(nowTime); System.out.println(nowTime.getHour()); System.out.println(nowTime.getMinute()); System.out.println(nowTime.getSecond()); System.out.println(nowTime.getNano()); System.out.println(separator); // 获取当前日期及时间 LocalDateTime nowDateTime = LocalDateTime.now(); System.out.println(nowDateTime); System.out.println(nowDateTime.getYear()); System.out.println(nowDateTime.getMonthValue()); System.out.println(nowDateTime.getDayOfMonth()); System.out.println(nowDateTime.getHour()); System.out.println(nowDateTime.getMinute()); System.out.println(nowDateTime.getSecond()); System.out.println(nowDateTime.getNano()); System.out.println(separator); // 获取指定日期的对象 System.out.println(LocalDate.of(2020, 05, 15)); System.out.println(LocalDate.of(2020, Month.MAY, 15)); // 其他指定时间的方式 LocalDate day = LocalDate.of(2020, 05, 15); // 第一个参数为年,第二个参数为当年的第多少天 System.out.println(LocalDate.ofYearDay(2020, day.getDayOfYear())); // 参数为距离时间纪元(1970-01-01)的天数 System.out.println(LocalDate.ofEpochDay(day.toEpochDay())); // 按格式解析 System.out.println(LocalDate.parse("2020-05-15")); System.out.println(LocalDate.parse("20200515", DateTimeFormatter.ofPattern("yyyyMMdd"))); System.out.println(separator); // 获取指定时间的对象 System.out.println(LocalTime.of(18, 30)); System.out.println(LocalTime.of(18, 30, 0)); System.out.println(LocalTime.of(18, 30, 0, 0)); LocalTime time = LocalTime.of(18, 30, 0, 0); System.out.println(LocalTime.ofSecondOfDay(time.toSecondOfDay())); System.out.println(LocalTime.ofNanoOfDay(time.toNanoOfDay())); System.out.println(LocalTime.parse("18:30:00")); System.out.println(LocalTime.parse("183000", DateTimeFormatter.ofPattern("HHmmss"))); System.out.println(separator); // 获取指定日期时间的对象 System.out.println(LocalDateTime.of(day, time)); System.out.println(LocalDateTime.of(2020, 05, 15, 18, 30)); System.out.println(LocalDateTime.of(2020, Month.MAY, 15, 18, 30)); System.out.println(LocalDateTime.of(2020, 05, 15, 18, 30, 0)); System.out.println(LocalDateTime.of(2020, 05, 15, 18, 30, 0, 0)); System.out.println(LocalDateTime.parse("2020-05-15T18:30:00")); System.out.println(LocalDateTime.parse("2020-05-15 18:30:00", DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"))); System.out.println(separator); // 时间日期的比较 LocalDate date1 = LocalDate.of(2020, 05, 15); LocalDate date2 = LocalDate.of(2018, 05, 15); System.out.println(date1.isBefore(date2)); System.out.println(date1.isAfter(date2)); System.out.println(date1.equals(date2)); System.out.println(separator); // 仅月日 or 仅年月 的获取方式(可用来重复表示每年的某一天) MonthDay monthDay = MonthDay.of(05, 15); YearMonth yearMonth = YearMonth.of(2020, 05); System.out.println(monthDay); System.out.println(yearMonth); System.out.println(yearMonth.lengthOfMonth()); // 这个月有多少天 System.out.println(separator); // 对日期时间的修改 LocalDateTime nowDateTime1 = LocalDateTime.now(); System.out.println(nowDateTime1); // 减去指定时间 System.out.println(nowDateTime1.minusYears(1)); System.out.println(nowDateTime1.minusMonths(1)); System.out.println(nowDateTime1.minusWeeks(1)); System.out.println(nowDateTime1.minusDays(1)); // 增加指定时间 System.out.println(nowDateTime1.plusYears(1)); System.out.println(nowDateTime1.plusMonths(1)); System.out.println(nowDateTime1.plusWeeks(1)); System.out.println(nowDateTime1.plusDays(1)); // 其他 System.out.println(nowDateTime1.minus(1, ChronoUnit.YEARS)); System.out.println(nowDateTime1.minus(1, ChronoUnit.HOURS)); System.out.println(nowDateTime1.plus(1, ChronoUnit.MONTHS)); System.out.println(separator); // 时间戳(Instant 与 JDK8 以前的 Date 相似,可以使用对应方法在这两个类型之间转换) Instant instant = Instant.now(); System.out.println(instant); Date date = Date.from(instant); System.out.println(date); System.out.println(date.toInstant()); System.out.println(separator); // 时间格式化(SimpleDateFormat 线程不安全,DateTimeFormatter 线程安全) LocalDateTime nowDateTime2 = LocalDateTime.now(); System.out.println(nowDateTime2); DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); System.out.println(formatter.format(nowDateTime2)); System.out.println(nowDateTime2.format(formatter)); System.out.println(separator); // 计算时间差 // Period 表示日期之间得差(年月日) LocalDate day1 = LocalDate.of(1990, 05, 15); LocalDate nowDate1 = LocalDate.now(); Period period = Period.between(day1, nowDate1); System.out.printf("年龄:%d 年 %d 月 %d 日", period.getYears(), period.getMonths(), period.getDays()); // Duration 表示时间差(日时分秒) LocalDateTime nowDateTime3 = LocalDateTime.of(1990, 05, 15, 18, 30, 0); LocalDateTime nowDateTime4 = LocalDateTime.now(); Duration duration = Duration.between(nowDateTime3, nowDateTime4); System.out.println(duration.toDays()); System.out.println(duration.toHours()); System.out.println(duration.toMinutes()); System.out.println(duration.toMillis()); System.out.println(duration.toNanos()); // ChronoUnit 类可用于在单个时间单位内测量一段时间 LocalDateTime today = LocalDateTime.now(); LocalDateTime birthDate = LocalDateTime.of(1990, 05, 15, 18, 30, 0); System.out.println(today); 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)); } /** * LocalDateTime 不包含时区信息,ZonedDateTime 包含时区信息 */ @Test public void testZoneDateTime() { // 未设置时区打印信息 System.out.println(LocalDateTime.now()); System.out.println(ZonedDateTime.now()); // 设置时区后打印信息 TimeZone.setDefault(TimeZone.getTimeZone("Asia/Shanghai"));// 设置默认时区 System.out.println(LocalDateTime.now()); System.out.println(ZonedDateTime.now()); /* 打印结果: 2020-04-03T12:11:06.098 2020-04-03T12:11:06.100Z[UTC] 2020-04-03T20:11:06.203 2020-04-03T20:11:06.203+08:00[Asia/Shanghai] */ /* 与 LocalDateTime 的区别是,ZonedDateTime 内部记录了时区,而 LocalDateTime 没有。 因此 LocalDateTime 转 Instant 需要指定 ZoneOffSet 而 ZonedDateTime 不需要。 */ Instant instant1 = LocalDateTime.now().toInstant(ZoneOffset.of("+08:00")); Instant instant2 = ZonedDateTime.now().toInstant(); System.out.println(instant1); System.out.println(instant2); System.out.println(instant1.getEpochSecond()); System.out.println(instant2.getEpochSecond()); System.out.println(System.currentTimeMillis()); } } ```

分类:编程     关键词:时间日期

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