JDK8 日期时间相关 java.time.*

LocalDateTime, LocalTime,LocalDate 区别

LocalDate：不包含具体时间的日期 2022-04-15

LocalTime：不含日期的时间 16:11:45.864

LocalDateTime：包含了日期及时间 2022-04-15T16:11:18.292

scala>
import java.time.{LocalDateTime, LocalTime,LocalDate,Duration, Instant}scala> LocalDate.now()
val res3: java.time.LocalDate = 2022-04-15scala> LocalDateTime.now()
val res6: java.time.LocalDateTime = 2022-04-15T16:11:18.292scala> LocalTime.now()
val res9: java.time.LocalTime = 16:11:45.864scala> Instant.now()
val res11: java.time.Instant = 2022-04-15T08:11:53.730Z

LocalDateTime

scala> val  nowDateTime = LocalDateTime.now()
val nowDateTime: java.time.LocalDateTime = 2022-04-15T16:26:23.701

LocalDateTime.now().get

得到年月日(本年、本月、本周)

scala> nowDateTime.getYear
val res64: Int = 2022scala> nowDateTime.getMonth()
val res67: java.time.Month = APRILscala> nowDateTime.getMonthValue()
val res69: Int = 4scala> nowDateTime.getDayOf
getDayOfMonth()   getDayOfWeek()    getDayOfYear()

LocalDateTime 转为LocalDate 和LocalTime

scala> nowDateTime.toLocalDate
val res81: java.time.LocalDate = 2022-04-15scala> nowDateTime.toLocalTime
val res83: java.time.LocalTime = 16:26:23.701scala> nowDateTime.toString
val res86: String = 2022-04-15T16:26:23.701

加减时间

scala> nowDateTime.plusYears(12)
val res186: java.time.LocalDateTime = 2034-04-15T16:26:23.701

truncateTo

scala> nowDateTime.truncatedTo(ChronoUnit.HOURS)
val res194: java.time.LocalDateTime = 2022-04-15T16:00scala> nowDateTime.truncatedTo(ChronoUnit.DAYS)
val res203: java.time.LocalDateTime = 2022-04-15T00:00scala> nowDateTime.truncatedTo(ChronoUnit.WEEKS)
java.time.temporal.UnsupportedTemporalTypeException: Unit is too large to be used for truncationat java.time.LocalTime.truncatedTo(LocalTime.java:955)at java.time.LocalDateTime.truncatedTo(LocalDateTime.java:1121)... 32 elidedscala> nowDateTime.truncatedTo(ChronoUnit.MINUTES)
val res211: java.time.LocalDateTime = 2022-04-15T16:26scala> nowDateTime.truncatedTo(ChronoUnit.SECONDS)
val res212: java.time.LocalDateTime = 2022-04-15T16:26:23

LocalDate

scala> val nowDate=LocalDate.now()
val nowDate: java.time.LocalDate = 2022-04-15

获取年、月、日、当月的第几天

scala> nowDate.getYear()
val res43: Int = 2022scala> nowDate.getMonth
val res45: java.time.Month = APRILscala> nowDate.getMonth
def getMonth(): java.time.Month
scala> nowDate.getMonthValue
val res49: Int = 4

获取本年、本月、本周的第几天

scala> nowDate.getDayOfMonth
val res52: Int = 15scala> nowDate.getDayOfYear
val res54: Int = 105scala> nowDate.getDayOfWeek
val res56: java.time.DayOfWeek = FRIDAY

LocalTime

val nowTime = LocalTime.now()

得到当前时间的时、分、秒、纳秒

scala> nowTime.getHour
val res26: Int = 16scala> nowTime.getMinute
val res29: Int = 17scala> nowTime.getSecond
val res31: Int = 3scala> nowTime.getNano
val res38: Int = 724000000

日期时间格式化java.time.format.DateTimeFormatter

scala> val dtf: DateTimeFormatter =DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")
val dtf: java.time.format.DateTimeFormatter = Value(YearOfEra,4,19,EXCEEDS_PAD)'-'Value(MonthOfYear,2)'-'Value(DayOfMonth,2)' 'Value(HourOfDay,2)':'Value(MinuteOfHour,2)':'Value(SecondOfMinute,2)scala> nowDateTime.format(dtf)
val res99: String = 2022-04-15 16:26:23scala> dtf.format(nowDateTime)
val res100: String = 2022-04-15 16:26:23scala> val dtf: DateTimeFormatter =DateTimeFormatter.ofPattern("yyyyMMdd HH:mm:ss")
val dtf: java.time.format.DateTimeFormatter = Value(YearOfEra,4,19,EXCEEDS_PAD)Value(MonthOfYear,2)Value(DayOfMonth,2)' 'Value(HourOfDay,2)':'Value(MinuteOfHour,2)':'Value(SecondOfMinute,2)scala> dtf.format(nowDateTime)
val res101: String = 20220415 16:26:23scala> nowDateTime.format(dtf)
val res102: String = 20220415 16:26:23

计算时间差 java.time.Period

Periods getYears()，getMonths() 和 getDays() – 精确到年月日

scala> val birDate=LocalDate.of(2000,11,8)
val birDate: java.time.LocalDate = 2000-11-08
scala> Period.between(nowDate,birDate)
val res123: java.time.Period = P-21Y-5M-7Dscala> Period.between(nowDate,birDate).getDays
val res126: Int = -7scala> Period.between(nowDate,birDate).getYears
val res128: Int = -21

计算时间差是后面日期减去前面日期

java.time.Duration

scala> import java.time.Duration
import java.time.Durationscala> val birdate=LocalDateTime.of(2000,11,8,18,30)
val birdate: java.time.LocalDateTime = 2000-11-08T18:30scala> val duration=Duration.between(birdate,nowDateTime)
val duration: java.time.Duration = PT187869H56M23.701S

得到时间差


scala> duration.toDays
val res136: Long = 7827scala> duration.toHours
val res141: Long = 187869scala> duration.toMinutes
val res146: Long = 11272196scala> duration.toNanos
val res148: Long = 676331783701000000

java.time.temporal.ChronoUnit

scala> import java.time.temporal.ChronoUnit
import java.time.temporal.ChronoUnitscala> ChronoUnit.DAYS
val res156: java.time.temporal.ChronoUnit = Daysscala> ChronoUnit.DAYS.between(birDate,nowDateTime)
val res161: Long = 7828scala> ChronoUnit.DAYS.between(birDate,nowDate)
val res162: Long = 7828scala> ChronoUnit.YEARS.between(birDate,nowDate)
val res164: Long = 21

获取昨天日期

import java.text.SimpleDateFormat
import java.util.{Calendar, Date}
def getYesterday(): String = {val dateFormat: SimpleDateFormat = new SimpleDateFormat("yyyyMMdd")val cal: Calendar = Calendar.getInstance()cal.add(Calendar.DATE, -1)dateFormat.format(cal.getTime())}

字符串转时间LocalDateTime

LocalDateTime.of(2021, 10, 22, 10, 10, 10);

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