本文用示例介绍java的Period的用法。
说明
Duration类通过秒和纳秒相结合来描述一个时间量，最高精度是纳秒。时间量可以为正也可以为负，比如1天（86400秒0纳秒）、-1天（-86400秒0纳秒）、1年（31556952秒0纳秒）、1毫秒（0秒1000000纳秒）等。
Period类通过年、月、日相结合来描述一个时间量，最高精度是天。时间量可以为正也可以为负，例如2年（2年0个月0天）、3个月（0年3个月0天）、4天（0年0月4天）等。
这两个类是不可变的、线程安全的、最终类。都是JDK8新增的。
Duration用法
如果仅一个值表示，如使用ofDays()方法，那么其他值为0。
若仅用ofWeeks，则其天数为week数乘以7.
Period fromUnits = Period.of(3, 10, 10); Period fromDays = Period.ofDays(50); Period fromMonths = Period.ofMonths(5); Period fromYears = Period.ofYears(10); Period fromWeeks = Period.ofWeeks(40); //280天
LocalDate startDate = LocalDate.of(2015, 2, 20); LocalDate endDate = LocalDate.of(2017, 1, 15); // startDate减endDate Period period = Period.between(startDate, endDate);
格式1：“PnYnMnWnD”
P：开始符，表示period（即：表示年月日）；
Y：year；
M：month；
W：week；
D：day
P, Y, M, W, D都可以用大写或者小写。
Period period = Period.parse("P2Y"); //2年
Period period = Period.parse("P2Y3M5D"); //2年3月5天
Period period = Period.parse("P1Y2M3W4D"); // 1年2月3周4天。即：1年2月25天
源码
public final class Period
implements ChronoPeriod, Serializable {
//-----------------------------------------------------------------------
/**
* Obtains a {@code Period} from a text string such as {@code PnYnMnD}.
* <p>
* This will parse the string produced by {@code toString()} which is
* based on the ISO-8601 period formats {@code PnYnMnD} and {@code PnW}.
* <p>
* The string starts with an optional sign, denoted by the ASCII negative
* or positive symbol. If negative, the whole period is negated.
* The ASCII letter "P" is next in upper or lower case.
* There are then four sections, each consisting of a number and a suffix.
* At least one of the four sections must be present.
* The sections have suffixes in ASCII of "Y", "M", "W" and "D" for
* years, months, weeks and days, accepted in upper or lower case.
* The suffixes must occur in order.
* The number part of each section must consist of ASCII digits.
* The number may be prefixed by the ASCII negative or positive symbol.
* The number must parse to an {@code int}.
* <p>
* The leading plus/minus sign, and negative values for other units are
* not part of the ISO-8601 standard. In addition, ISO-8601 does not
* permit mixing between the {@code PnYnMnD} and {@code PnW} formats.
* Any week-based input is multiplied by 7 and treated as a number of days.
* <p>
* For example, the following are valid inputs:
* <pre>
* "P2Y" -- Period.ofYears(2)
* "P3M" -- Period.ofMonths(3)
* "P4W" -- Period.ofWeeks(4)
* "P5D" -- Period.ofDays(5)
* "P1Y2M3D" -- Period.of(1, 2, 3)
* "P1Y2M3W4D" -- Period.of(1, 2, 25)
* "P-1Y2M" -- Period.of(-1, 2, 0)
* "-P1Y2M" -- Period.of(-1, -2, 0)
* </pre>
*
* @param text the text to parse, not null
* @return the parsed period, not null
* @throws DateTimeParseException if the text cannot be parsed to a period
*/
public static Period parse(CharSequence text) {
// 其他代码
}
// 其他代码
}
获得年月日
period.getYears(); period.getMonths(); period.getDays();
用between来比较日期。
LocalDate startDate = LocalDate.of(2015, 2, 20); LocalDate endDate = LocalDate.of(2017, 1, 15); // startDate减endDate Period period = Period.between(startDate, endDate); // 任何一个时间单元为负数，则返回true。true：endDate早于startDate period.isNegative()
Period period = Period.parse("P2Y3M5D");
period.plusDays(50);
period.minusMonths(2);
Period period = Period.parse("P1Y2M3D");
period.toTotalMonths(); // 14
Period period = Period.parse("P1Y2M3D");
period.getYears(); // 1
period.getMonths(); // 2
period.getDays(); // 3
