Java日期计算

1、时间类得作成

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//方法一：取系统点间  DateTime dt1 = new DateTime();      //方法二：通过java.util.Date对象生成  DateTime dt2 = new DateTime(new Date());      //方法三：指定年月日点分秒生成(参数依次是：年,月,日,时,分,秒,毫秒)  DateTime dt3 = new DateTime(2012, 5, 20, 13, 14, 0, 0);      //方法四：ISO8601形式生成  DateTime dt4 = new DateTime("2012-05-20");  DateTime dt5 = new DateTime("2012-05-20T13:14:00");      //只需要年月日的时候  LocalDate localDate = new LocalDate(2009, 9, 6);// September 6, 2009      //只需要时分秒毫秒的时候  LocalTime localTime = new LocalTime(13, 30, 26, 0);// 1:30:26PM

　2、获取年月日点分秒

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DateTime dt = new DateTime();  //年  int year = dt.getYear();  //月  int month = dt.getMonthOfYear();  //日  int day = dt.getDayOfMonth();  //星期  int week = dt.getDayOfWeek();  //点  int hour = dt.getHourOfDay();  //分  int min = dt.getMinuteOfHour();  //秒  int sec = dt.getSecondOfMinute();  //毫秒  int msec = dt.getMillisOfSecond();

　3、星期的特殊处理

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DateTime dt = new DateTime();      //星期  switch(dt.getDayOfWeek()) {  case DateTimeConstants.SUNDAY:      System.out.println("星期日");      break;  case DateTimeConstants.MONDAY:      System.out.println("星期一");      break;  case DateTimeConstants.TUESDAY:      System.out.println("星期二");      break;  case DateTimeConstants.WEDNESDAY:      System.out.println("星期三");      break;  case DateTimeConstants.THURSDAY:      System.out.println("星期四");      break;  case DateTimeConstants.FRIDAY:      System.out.println("星期五");      break;  case DateTimeConstants.SATURDAY:      System.out.println("星期六");      break;  }

　4、与JDK日期对象的转换

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DateTime dt = new DateTime();      //转换成java.util.Date对象  Date d1 = new Date(dt.getMillis());  Date d2 = dt.toDate();      //转换成java.util.Calendar对象  Calendar c1 = Calendar.getInstance();  c1.setTimeInMillis(dt.getMillis());  Calendar c2 = dt.toCalendar(Locale.getDefault());

5、日期前后推算

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DateTime dt = new DateTime();      //昨天  DateTime yesterday = dt.minusDays(1);         //明天  DateTime tomorrow = dt.plusDays(1);       //1个月前  DateTime before1month = dt.minusMonths(1);        //3个月后  DateTime after3month = dt.plusMonths(3);          //2年前  DateTime before2year = dt.minusYears(2);          //5年后  DateTime after5year = dt.plusYears(5);

6、取特殊日期

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DateTime dt = new DateTime();         //月末日期    DateTime lastday = dt.dayOfMonth().withMaximumValue();      //90天后那周的周一  DateTime firstday = dt.plusDays(90).dayOfWeek().withMinimumValue();

7、时区

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//默认设置为日本时间  DateTimeZone.setDefault(DateTimeZone.forID("Asia/Tokyo"));  DateTime dt1 = new DateTime();      //伦敦时间  DateTime dt2 = new DateTime(DateTimeZone.forID("Europe/London"));

8、计算区间

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DateTime begin = new DateTime("2012-02-01");  DateTime end = new DateTime("2012-05-01");      //计算区间毫秒数  Duration d = new Duration(begin, end);  long time = d.getMillis();      //计算区间天数  Period p = new Period(begin, end, PeriodType.days());  int days = p.getDays();      //计算特定日期是否在该区间内  Interval i = new Interval(begin, end);  boolean contained = i.contains(new DateTime("2012-03-01"));

9、日期比较

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DateTime d1 = new DateTime("2012-02-01");  DateTime d2 = new DateTime("2012-05-01");      //和系统时间比  boolean b1 = d1.isAfterNow();  boolean b2 = d1.isBeforeNow();  boolean b3 = d1.isEqualNow();      //和其他日期比  boolean f1 = d1.isAfter(d2);  boolean f2 = d1.isBefore(d2);  boolean f3 = d1.isEqual(d2);

10、格式化输出

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DateTime dateTime = new DateTime();      String s1 = dateTime.toString("yyyy/MM/dd hh:mm:ss.SSSa");  String s2 = dateTime.toString("yyyy-MM-dd HH:mm:ss");  String s3 = dateTime.toString("EEEE dd MMMM, yyyy HH:mm:ssa");  String s4 = dateTime.toString("yyyy/MM/dd HH:mm ZZZZ");  String s5 = dateTime.toString("yyyy/MM/dd HH:mm Z");