详解Java中Period类的使用方法

简介

本文用示例介绍java的Period的用法。

Duration和Period

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

见：详解Java中Duration类的使用方法

创建方法

通过时间单位创建

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

通过LocalDate创建

LocalDate startDate = LocalDate.of(2015, 2, 20);
LocalDate endDate = LocalDate.of(2017, 1, 15);
// startDate减endDate
Period period = Period.between(startDate, endDate);

解析方法

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();

比较方法

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()

增减方法

Period period = Period.parse("P2Y3M5D");
period.plusDays(50);
period.minusMonths(2);

转换单位

Period period = Period.parse("P1Y2M3D");
period.toTotalMonths(); // 14

取值方法

Period period = Period.parse("P1Y2M3D");
period.getYears();  // 1
period.getMonths(); // 2
period.getDays();   // 3

来源：https://knife.blog.csdn.net/article/details/122772818