LocalDate、LocalDateTime、LocalTime开发小结
在我之前的文章《【整理】Java 8新特性总结 》中有提到Date/Time API (JSR 310)对日期与时间的处理。它将服务端对时间的处理进行了统一，使得对时间的处理更加规范和统一。
本文主要是对Date/Time API开发过程中的小结。
Date 和LocalDate、LocalDateTime、LocalTime之间的转换
Date转LocalDate、LocalDateTime、LocalTime
public static void main(String[] args) { Date date = new Date(); Instant instant = date.toInstant(); ZoneId zoneId = ZoneId.systemDefault(); // atZone()方法返回在指定时区从此Instant生成的ZonedDateTime。 LocalDate localDate = instant.atZone(zoneId).toLocalDate(); LocalDateTime localDateTime = instant.atZone(zoneId).toLocalDateTime(); LocalTime localTime = instant.atZone(zoneId).toLocalTime(); System.out.println("Date = " + date);//Wed Apr 24 14:43:25 CST 2019 System.out.println("LocalDate = " + localDate);//2019-04-24 System.out.println("LocalDateTime = " + localDateTime);//2019-04-24T14:43:25.030 System.out.println("LocalTime = " + localTime);//14:43:25.030 }
LocalDateTime转Date
public static void main(String[] args) { LocalTime localTime = LocalTime.now(); LocalDate localDate = LocalDate.now(); LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime); ZoneId zone = ZoneId.systemDefault(); Instant instant = localDateTime.atZone(zone).toInstant(); java.util.Date date = Date.from(instant); System.out.println("LocalDate = "+localDate);//2019-04-24 System.out.println("LocalTime = "+localTime);//14:43:25.030 System.out.println("LocalDateTime = "+localDateTime);//2019-04-24T14:43:25.030 System.out.println("Date = "+date);//Wed Apr 24 14:43:25 CST 2019 }
LocalDateTime与LocalTime、LocalDate之间的转换
LocalDateTime转LocalTime、LocalDate
public static void main(String[] args) { LocalDateTime localDateTime = LocalDateTime.now(); LocalDate localDate = localDateTime.toLocalDate(); LocalTime localTime = localDateTime.toLocalTime(); System.out.println("LocalDateTime = "+localDateTime);//2019-04-24T14:43:25.030 System.out.println("LocalDate = "+localDate);//2019-04-24 System.out.println("LocalTime = "+localTime);//14:43:25.030 }
LocalDate转LocalDateTime
public static void main(String[] args) { LocalDate localDate =LocalDate.now(); LocalDateTime localDateTime = localDate.atStartOfDay(); LocalDateTime localDateTime2 = localDate.atTime(LocalTime.now()); LocalDateTime localDateTime1 = LocalDateTime.of(localDate,LocalTime.MAX); System.out.println(localDate);//2019-04-24 System.out.println(localDateTime);//2019-04-24T00:00 System.out.println(localDateTime1);//2019-04-24T23:59:59.999999999 System.out.println(localDateTime2);//2019-04-24T15:18:41.823 }
String和LocalDateTime之间的转换
LocalDateTime转String
public static void main(String[] args) { //定义时间格式化 DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); DateTimeFormatter dtf1 = DateTimeFormatter.ofPattern("yyyy.MM.dd HH:mm"); LocalDateTime ldt = LocalDateTime.now(); String time = dtf.format(ldt); String time1 = dtf1.format(ldt); System.out.println(time);//2019-04-24 15:58:04 System.out.println(time1);//2019.04.24 15:58 }
String转LocalDateTime
public static void main(String[] args) { DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); LocalDateTime localDateTime = LocalDateTime.parse("2019-04-24 15:33:23",dtf); System.out.println(localDateTime);//2019-04-24T15:33:23 }
时间戳和LocalDateTime之间的转换
localDateTime转时间戳
public static void main(String[] args) { System.out.println(LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli());//1556095208585 毫秒 System.out.println(LocalDateTime.now().toInstant(ZoneOffset.of("+8")).getEpochSecond());//1556095208585 秒 }
时间戳转localDateTime
public static void main(String[] args) { Long timestamp = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).getEpochSecond(); LocalDateTime time2 =LocalDateTime.ofEpochSecond(timestamp,0,ZoneOffset.ofHours(8)); System.out.println(time2); }
其他
LocalDateTime.now().plus(100000, ChronoUnit.DAYS)
同 LocalDateTime.now().plusDays(100000)
LocalDateTime.now().get(ChronoField.DAY_OF_MONTH)
同 LocalDateTime.now().getDayOfMonth()
ChronoUnit枚举
public enum ChronoUnit implements TemporalUnit { NANOS("Nanos", Duration.ofNanos(1)), MICROS("Micros", Duration.ofNanos(1000)), MILLIS("Millis", Duration.ofNanos(1000_000)), SECONDS("Seconds", Duration.ofSeconds(1)), MINUTES("Minutes", Duration.ofSeconds(60)), HOURS("Hours", Duration.ofSeconds(3600)), HALF_DAYS("HalfDays", Duration.ofSeconds(43200)), DAYS("Days", Duration.ofSeconds(86400)), WEEKS("Weeks", Duration.ofSeconds(7 * 86400L)), MONTHS("Months", Duration.ofSeconds(31556952L / 12)), YEARS("Years", Duration.ofSeconds(31556952L)), DECADES("Decades", Duration.ofSeconds(31556952L * 10L)), CENTURIES("Centuries", Duration.ofSeconds(31556952L * 100L)), MILLENNIA("Millennia", Duration.ofSeconds(31556952L * 1000L)), ERAS("Eras", Duration.ofSeconds(31556952L * 1000_000_000L)), FOREVER("Forever", Duration.ofSeconds(Long.MAX_VALUE, 999_999_999)); private final String name; private final Duration duration; private ChronoUnit(String name, Duration estimatedDuration) { this.name = name; this.duration = estimatedDuration; } }
ChronoField枚举
public enum ChronoField implements TemporalField { NANO_OF_SECOND("NanoOfSecond", NANOS, SECONDS, ValueRange.of(0, 999_999_999)), NANO_OF_DAY("NanoOfDay", NANOS, DAYS, ValueRange.of(0, 86400L * 1000_000_000L - 1)), MICRO_OF_SECOND("MicroOfSecond", MICROS, SECONDS, ValueRange.of(0, 999_999)), MICRO_OF_DAY("MicroOfDay", MICROS, DAYS, ValueRange.of(0, 86400L * 1000_000L - 1)), MILLI_OF_SECOND("MilliOfSecond", MILLIS, SECONDS, ValueRange.of(0, 999)), MILLI_OF_DAY("MilliOfDay", MILLIS, DAYS, ValueRange.of(0, 86400L * 1000L - 1)), SECOND_OF_MINUTE("SecondOfMinute", SECONDS, MINUTES, ValueRange.of(0, 59), "second"), SECOND_OF_DAY("SecondOfDay", SECONDS, DAYS, ValueRange.of(0, 86400L - 1)), MINUTE_OF_HOUR("MinuteOfHour", MINUTES, HOURS, ValueRange.of(0, 59), "minute"), MINUTE_OF_DAY("MinuteOfDay", MINUTES, DAYS, ValueRange.of(0, (24 * 60) - 1)), HOUR_OF_AMPM("HourOfAmPm", HOURS, HALF_DAYS, ValueRange.of(0, 11)), CLOCK_HOUR_OF_AMPM("ClockHourOfAmPm", HOURS, HALF_DAYS, ValueRange.of(1, 12)), HOUR_OF_DAY("HourOfDay", HOURS, DAYS, ValueRange.of(0, 23), "hour"), CLOCK_HOUR_OF_DAY("ClockHourOfDay", HOURS, DAYS, ValueRange.of(1, 24)), AMPM_OF_DAY("AmPmOfDay", HALF_DAYS, DAYS, ValueRange.of(0, 1), "dayperiod"), DAY_OF_WEEK("DayOfWeek", DAYS, WEEKS, ValueRange.of(1, 7), "weekday"),
ALIGNED_DAY_OF_WEEK_IN_MONTH("AlignedDayOfWeekInMonth", DAYS, WEEKS, ValueRange.of(1, 7)),
ALIGNED_DAY_OF_WEEK_IN_YEAR("AlignedDayOfWeekInYear", DAYS, WEEKS, ValueRange.of(1, 7)), DAY_OF_MONTH("DayOfMonth", DAYS, MONTHS, ValueRange.of(1, 28, 31), "day"), DAY_OF_YEAR("DayOfYear", DAYS, YEARS, ValueRange.of(1, 365, 366)), EPOCH_DAY("EpochDay", DAYS, FOREVER, ValueRange.of((long) (Year.MIN_VALUE * 365.25), (long) (Year.MAX_VALUE * 365.25))), ALIGNED_WEEK_OF_MONTH("AlignedWeekOfMonth", WEEKS, MONTHS, ValueRange.of(1, 4, 5)), ALIGNED_WEEK_OF_YEAR("AlignedWeekOfYear", WEEKS, YEARS, ValueRange.of(1, 53)), MONTH_OF_YEAR("MonthOfYear", MONTHS, YEARS, ValueRange.of(1, 12), "month"), YEAR("Year", YEARS, FOREVER, ValueRange.of(Year.MIN_VALUE, Year.MAX_VALUE), "year"), private final String name; private final TemporalUnit baseUnit; private final TemporalUnit rangeUnit; private final ValueRange range; private final String displayNameKey; private ChronoField(String name, TemporalUnit baseUnit, TemporalUnit rangeUnit, ValueRange range) { this.name = name; this.baseUnit = baseUnit; this.rangeUnit = rangeUnit; this.range = range; this.displayNameKey = null; } }
