Java 8 推出了全新的日期时间API并且已经很久了，因为业务中遇到的时间处理的还是不多，因此用的也少，而且大多是用封装好的时间共计包，就更少接触java8 的时间类型API了，因此对他不是很熟，今天遇到了一下问题打算总结一下： Java处理日期、日历和时间的不足之处：将 java.util.Date 设定为可变类型，以及 SimpleDateFormat 的非线程安全使其应用非常受限。然后就在 java8 上面增加新的特性。 全新API的好处之一就是，明确了日期时间概念，例如：瞬时（instant）、 长短（duration）、日期、时间、时区和周期这些概念都是分开的，并且有独立的对象来处理。 重要的是：同时继承了Joda 库按人类语言和计算机各自解析的时间处理方式。不同于老版本，新API基于ISO标准日历系统，java.time包下的***所有类都是不可变类型而且线程安全***。 Instant：瞬时实例。 LocalTime：本地时间，不包含日期。只有时分秒纳秒等信息 LocalDate：本地日期，不包含具体时间 例如：2014-01-14 可以用来记录生日、纪念日、加盟日等。只有年月日信息 LocalDateTime：组合了日期和时间，但不包含时差和时区信息。包含所有年月日时分秒纳秒等信息 以上三个是类似的PAI，都有差不多一样的方法和处理方式，只是表达的时间范围是不一样的。这一点用起来还是非常方便的 ZonedDateTime：最完整的日期时间，包含时区和相对UTC或格林威治的时差。这个类用来处理带时区的时间信息 新API还引入了 ZoneOffSet 和 ZoneId 类，使得解决时区问题更为简便。解析、格式化时间的 DateTimeFormatter 类也全部重新设计。具体时区用这两个处理 public static void getCurrentDate ( ) { LocalDate today = LocalDate. now ( ) ; System. out. println ( "today's local date: " + today) ; Date date = new Date ( ) ; System. out. println ( "today's date is: " + date) ; }
public static void getDetailDate ( ) { LocalTime todayTime = LocalTime. now ( ) ; int second = todayTime. getSecond ( ) ; int minute = todayTime. getMinute ( ) ; int hour = todayTime. getHour ( ) ; int nano = todayTime. getNano ( ) ; System. out. println ( "秒: " + second + "分: " + minute + "时: " + hour + "纳秒: " + nano) ; LocalDate today = LocalDate. now ( ) ; int year = today. getYear ( ) ; int month = today. getMonthValue ( ) ; int day = today. getDayOfMonth ( ) ; int day_year = today. getDayOfYear ( ) ; System. out. println ( year + ": " + month + ": " + day + ": " + day_year) ; LocalDateTime localDateTime = LocalDateTime. now ( ) ; System. out. println ( localDateTime. getHour ( ) ) ; }
public static void handleSpecilDate ( ) { LocalDate localDate = LocalDate. of ( 2021 , 11 , 18 ) ; System. out. println ( localDate) ; LocalDate date = LocalDate. of ( 2021 , 6 , 18 ) ; System. out. println ( localDate. equals ( date) ) ; }
public static void cycleDate ( ) { LocalDate localDate = LocalDate. now ( ) ; LocalDate dateofBirth = LocalDate. of ( 2021 , 6 , 18 ) ; MonthDay birthday = MonthDay. of ( dateofBirth. getMonth ( ) , dateofBirth. getDayOfMonth ( ) ) ; MonthDay nowDate = MonthDay. from ( localDate) ; MonthDay monthParse = MonthDay. parse ( "2021-06-18" , DateTimeFormatter. ofPattern ( "yyyy-MM-dd" ) ) ; System. out. println ( birthday. equals ( nowDate) ) ; System. out. println ( monthParse) ; }
public static void checkCardExpiry ( ) { YearMonth currenctYearMonth = YearMonth. now ( ) ; System. out. println ( currenctYearMonth + ": " + currenctYearMonth. lengthOfMonth ( ) ) ; YearMonth credtCard = YearMonth. of ( 2021 , Month. FEBRUARY) ; System. out. println ( credtCard + ": " + credtCard. lengthOfMonth ( ) ) ; DayOfWeek dayOfWeek = DayOfWeek. of ( 3 ) ; System. out. println ( dayOfWeek) ; }
public static void plusHours ( ) { LocalTime localTime = LocalTime. now ( ) ; localTime. plusHours ( 5 ) ; System. out. println ( localTime) ; LocalTime nextWeek = localTime. plus ( 10 , ChronoUnit. HOURS) ; System. out. println ( nextWeek) ; System. out. println ( localTime) ; LocalTime halfDay = localTime. plus ( 2 , ChronoUnit. HALF_DAYS) ; System. out. println ( halfDay) ; } public static void plusDate ( ) { LocalDate localDate = LocalDate. now ( ) ; LocalDate tomorrow = localDate. plus ( 1 , ChronoUnit. DAYS) ; System. out. println ( tomorrow) ; LocalDate nextYear = localDate. plus ( 1 , ChronoUnit. YEARS) ; LocalDate beforeYear = localDate. minus ( 1 , ChronoUnit. YEARS) ; System. out. println ( "nextYear: " + nextYear) ; System. out. println ( "beforeYear: " + beforeYear) ; } public static void plusTime ( ) { LocalDateTime localDateTime = LocalDateTime. now ( ) ; System. out. println ( localDateTime) ; LocalDateTime afterHour = localDateTime. plus ( 1 , ChronoUnit. HOURS) . plus ( 1 , ChronoUnit. MINUTES) . plus ( 1 , ChronoUnit. YEARS) ; System. out. println ( afterHour) ; LocalDateTime nowDate = LocalDateTime. of ( 2021 , 6 , 19 , 17 , 23 , 57 ) ; System. out. println ( nowDate) ; } public static void checkTimes ( ) { LocalDateTime localDateTime = LocalDateTime. now ( ) ; LocalDateTime afterDate = LocalDateTime. of ( 2021 , 6 , 19 , 17 , 23 , 57 ) ; System. out. println ( localDateTime. isBefore ( afterDate) ) ; System. out. println ( localDateTime. isAfter ( afterDate) ) ; }
public static void zoneTime ( ) { ZoneId america = ZoneId. of ( "America/Chicago" ) ; LocalDateTime dateAndTime = LocalDateTime. now ( ) ; ZonedDateTime dateTimeInChicago = ZonedDateTime. of ( dateAndTime, america) ; System. out. println ( dateTimeInChicago) ; ZonedDateTime dateTimeInShenZhen = ZonedDateTime. ofInstant ( Instant. now ( ) , ZoneId. systemDefault ( ) ) ; System. out. println ( dateTimeInShenZhen) ; } public static void zoneOffSet ( ) { LocalDateTime localDateTime = LocalDateTime. of ( 2021 , Month. FEBRUARY, 14 , 19 , 24 ) ; ZoneOffset offset = ZoneOffset. of ( "+07:30" ) ; OffsetDateTime dateTime = OffsetDateTime. of ( localDateTime, offset) ; System. out. println ( dateTime) ; }
public static void isLeapYear ( ) { LocalDate today = LocalDate. now ( ) ; System. out. println ( today. getYear ( ) + "年是闰年：" + today. isLeapYear ( ) ) ; }
* * * 计算日期之间年，月，天数* / public static void calcDate ( ) { LocalDate localDateTime = LocalDate. of ( 2021 , 10 , 28 ) ; LocalDate beforeDateTime = LocalDate. now ( ) . plus ( 3 , ChronoUnit. DAYS) ; Period period = Period. between ( localDateTime, beforeDateTime) ; System. out. println ( "year: " + period. getYears ( ) + " month:" + period. getMonths ( ) + " day:" + period. getDays ( ) ) ; }
public static void formatDate ( ) { String dayAfterTomorrow = "2021-06-18 15:53:06" ; DateTimeFormatter df = DateTimeFormatter. ofPattern ( "yyyy-MM-dd HH:mm:ss" ) ; LocalDateTime formatDateTime = LocalDateTime. parse ( dayAfterTomorrow, df) ; System. out. println ( "timeStr: " + dayAfterTomorrow + " dateTime:" + formatDateTime) ; String dayDate = "20210618" ; DateTimeFormatter dateDayFor = DateTimeFormatter. ofPattern ( "yyyyMMdd" ) ; LocalDate localDate = LocalDate. parse ( dayDate, dateDayFor) ; System. out. println ( "timeStr: " + dayDate + " dateTime:" + localDate) ; String dayTime = "160451" ; DateTimeFormatter dayTimeFor = DateTimeFormatter. ofPattern ( "HHmmss" ) ; LocalTime localTime = LocalTime. parse ( dayTime, dayTimeFor) ; System. out. println ( "timeStr: " + dayTime + " dateTime:" + localTime) ; }
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