java8日期

左手的ㄟ右手 2022-07-12 02:48 178阅读 0赞

Java 8中有一个叫LocalDate的类，它能用来表示今天的日期
    LocalDate today = LocalDate.now();
    int year = today.getYear();
    int month = today.getMonthValue();
    int day = today.getDayOfMonth();
    
    
    获取某个特定的日期
    
    
    LocalDate dateOfBirth = LocalDate.of(2010, 01, 14);
    
    
    
    
    检查两个日期是否相等
    
    
    LocalDate date1 = LocalDate.of(2014, 01, 14); 
    if(date1.equals(today)){
    
    
    }
    
    
    检查重复事件，比如说生日
    
    
    MonthDay表示的是某个重复出现的日子
    LocalDate dateOfBirth = LocalDate.of(2010, 01, 14);
    MonthDay birthday = MonthDay.of(dateOfBirth.getMonth(), dateOfBirth.getDayOfMonth());
    MonthDay currentMonthDay = MonthDay.from(today);
    if(currentMonthDay.equals(birthday)){
      System.out.println("birthday!!");
    }else{
      System.out.println("not birthday!!");
    }
    
    
    获取当前时间
    
    
    LocalTime time = LocalTime.now();
    
    
    增加时间里面的小时数
    
    
    LocalTime time = LocalTime.now();
    LocalTime newTime = time.plusHours(2); 
    
    
    获取1周后的日期
    
    
    LocalDate nextWeek = today.plus(1, ChronoUnit.WEEKS);
    
    
    一年前后的日期
    
    
    
    
    LocalDate previousYear = today.minus(1, ChronoUnit.YEARS);
    System.out.println("Date before 1 year : " + previousYear);
    LocalDate nextYear = today.plus(1, YEARS);
    System.out.println("Date after 1 year : " + nextYear);
    
    
    判断某个日期是在另一个日期的前面还是后面
    
    
    LocalDate tomorrow = LocalDate.of(2014, 1, 15); 、if(tommorow.isAfter(today)){
     System.out.println("Tomorrow comes after today");
    }
    
    
    LocalDate yesterday = today.minus(1, DAYS);
    if(yesterday.isBefore(today)){
    }
    
    
    处理不同的时区
    
    
    
    
    LocalDateTime localtDateAndTime = LocalDateTime.now();
    ZonedDateTime dateAndTimeInNewYork = ZonedDateTime.of(localtDateAndTime, america );
    
    
    表示固定的日期，比如信用卡过期时间
    
    
    YearMonth又是另一个组合，它代表的是像信用卡还款日，定期存款到期日，options到期日这类的日期
    YearMonth currentYearMonth = YearMonth.now(); System.out.printf("Days in month year %s: %d%n", currentYearMonth, currentYearMonth.lengthOfMonth());
    YearMonth creditCardExpiry = YearMonth.of(2018, Month.FEBRUARY);
    System.out.printf("Your credit card expires on %s %n", creditCardExpiry);
    
    
    检查闰年
    
    
    if(today.isLeapYear())
    
    
    两个日期之间包含多少天，多少个月
    
    
    LocalDate java8Release = LocalDate.of(2014, Month.MARCH, 14);
    Period periodToNextJavaRelease =Period.between(today, java8Release);
    System.out.println("Months left between today and Java 8 release : " + periodToNextJavaRelease.getMonths() );
    
    
    如何获取当前时间戳
    
    
    Instant timestamp = Instant.now();
    
    
    
    
    使用预定义的格式器来对日期进行解析/格式化
    
    
    String dayAfterTommorrow = "20140116";
    LocalDate formatted = LocalDate.parse(dayAfterTommorrow,DateTimeFormatter.BASIC_ISO_DATE);
    
    
    自定义的格式器来解析日期
    
    
    String goodFriday = "Apr 18 2014";
    try {
      DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMM dd yyyy");
      LocalDate holiday = LocalDate.parse(goodFriday, formatter);
      System.out.printf("Successfully parsed String %s, date is %s%n", goodFriday, holiday);
    } catch (DateTimeParseException ex) {
      System.out.printf("%s is not parsable!%n", goodFriday);
      ex.printStackTrace();
    }
    
    
    对日期进行格式化，转换成字符串
    
    
    LocalDateTime arrivalDate = LocalDateTime.now();
    try{
      DateTimeFormatter format = DateTimeFormatter.ofPattern("MMM dd yyyy hh:mm a");
      String landing = arrivalDate.format(format);
      System.out.printf("Arriving at : %s %n", landing);
    } catch (DateTimeException ex) {
      System.out.printf("%s can't be formatted!%n", arrivalDate);
      ex.printStackTrace();
    }
    
    
    Date转localDate
    
    
    Date date=new Date();
    LocalDate localDate=LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault()).toLocalDate();
    
    
    localDate转Date
    
    
    LocalDate localDate=LocalDate.now();
    Date date = Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
    localDateTime转Date
    Date start=Date.from(LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant());
    获取本月月初（带时分秒）
    LocalDateTime startTime=LocalDateTime.of(LocalDate.now().with(TemporalAdjusters.firstDayOfMonth()),LocalTime.MIN);
    获取本月月末（带时分秒）
     LocalDateTime endTime=LocalDateTime.of(LocalDate.now().with(TemporalAdjusters.lastDayOfMonth()),LocalTime.MAX);
    
    
    只获取本月月初和月末日期（不带时分秒 ）
    LocalDate.now().with(TemporalAdjusters.firstDayOfMonth())
    LocalDate.now().with(TemporalAdjusters.lastDayOfMonth())
    
    
    
    
    获取两个日期之间的日期
    ChronoUnit.DAYS.between(LocalDate.now(),LocalDate.of(2017,8,20));

LocalDate nowDate=LocalDate.now(); LocalDate create=LocalDate.of(2017,7,10); Long daysBetween=nowDate.toEpochDay()-create.toEpochDay()+1;

string转LocalDateLocalDate date=LocalDate.parse("20170713",DateTimeFormatter.ofPattern("yyyy-MM-dd"));DateTimeFormatter f = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");//时间转为字符串LocalDateTime date =LocalDateTime.now(); String str = date.format(f); // 2014-11-07 14:10:36 //字符串转为时间 date = LocalDateTime.parse(str,f);

1.获取本周第一天

LocalDate nowDate = LocalDate.now();

LocalDate first = nowDate.with(DayOfWeek.MONDAY);

LocalDateTime start = LocalDateTime.of(nowDate.with(DayOfWeek.MONDAY),LocalTime.MIN);