Period表示的是一个时间段，也就是一个持续时间，比如5秒，5年3个月20天，精确到年月日，有一个和Peroid类似的类是Duration，Duration表示的也是一个时间段，比Period时间更短，比如5秒、100纳秒。
这里我们重点介绍Peroid，我们把Peroid的API方法的使用都列举了一遍。
import java.time.LocalDate;
import java.time.Period;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
public class PeriodTest {
public static void main(String[] args) {
LocalDate now = LocalDate.now();
LocalDate now2 = now.plusDays(15);
//addTo
Period period = Period.ofDays(10);
System.out.println(period+" addTo "+ now +" = "+period.addTo(now));
System.out.println("-----------------------------------------");
//between
Period between = Period.between(now, now2);
System.out.println("between:"+between);
System.out.println("-----------------------------------------");
//equals
boolean equals = period.equals(between);
System.out.println("equals:"+equals);
Period period2 = Period.ofDays(10);
boolean equals2 = period.equals(period2);
System.out.println("equals比较的是值:"+equals2);
boolean equals3 = period == period2;
System.out.println("==比较的是地址:"+equals3);
System.out.println("-----------------------------------------");
//from
Period from = Period.from(period2);
System.out.println("from:"+from);
System.out.println("-----------------------------------------");
//get
long day = period.get(ChronoUnit.DAYS);
long month = period.get(ChronoUnit.MONTHS);
System.out.println("get day :"+day);
System.out.println("get month :"+month);
/*没有对应的时间单位会报错,例如：long l = period.get(ChronoUnit.HOURS);
Exception in thread "main" java.time.temporal.UnsupportedTemporalTypeException: Unsupported unit: Hours
at java.time.Period.get(Period.java:440)
at com.my.study.date.PeriodTest.main(PeriodTest.java:37)*/
System.out.println("getDays:"+period.getDays());
System.out.println("getMonths:"+period.getMonths());
System.out.println("getYears:"+period.getYears());
System.out.println("getChronology:"+period.getChronology());
System.out.println("-----------------------------------------");
//normalized：将年和月进行规范化，不对日进行规范化
//例如：3年15个月10天，方法处理后就是：4年3个月
Period periodNormalized = period.withMonths(15).withYears(3);
Period normalized = periodNormalized.normalized();
System.out.println("periodNormalized:"+periodNormalized);
System.out.println("normalized:"+normalized);
System.out.println("-----------------------------------------");
//减
Period minus = period.minus(period);
System.out.println("minus:"+minus);
System.out.println("minusDays 减1天:"+period.minusDays(1));
System.out.println("-----------------------------------------");
//加
Period plus = period.plus(period);
System.out.println("minus:"+plus);
System.out.println("minusDays 加1天:"+period.plusDays(1));
System.out.println("-----------------------------------------");
//乘
Period multipliedBy = period.multipliedBy(10);
System.out.println("multipliedBy:"+multipliedBy);
System.out.println("-----------------------------------------");
Period of = Period.of(10, 15, 20);
System.out.println("of:"+of);
System.out.println("-----------------------------------------");
LocalDate now1 = LocalDate.now();
Temporal temporal = period.subtractFrom(now1);
System.out.println("subtractFrom:"+temporal);
System.out.println("-----------------------------------------");
Period with = period.withYears(2).withMonths(5).withDays(20);
System.out.println("period调整前:"+period);
System.out.println("with:"+with);
System.out.println("-----------------------------------------");
}
}
输出：
P10D addTo 2021-07-13 = 2021-07-23
-----------------------------------------
between:P15D
-----------------------------------------
equals:false
equals比较的是值:true
==比较的是地址:false
-----------------------------------------
from:P10D
-----------------------------------------
get day :10
get month :0
getDays:10
getMonths:0
getYears:0
getChronology:ISO
-----------------------------------------
periodNormalized:P3Y15M10D
normalized:P4Y3M10D
-----------------------------------------
minus:P0D
minusDays 减1天:P9D
-----------------------------------------
minus:P20D
minusDays 加1天:P11D
-----------------------------------------
multipliedBy:P100D
-----------------------------------------
of:P10Y15M20D
-----------------------------------------
subtractFrom:2021-07-03
-----------------------------------------
period调整前:P10D
with:P2Y5M20D
-----------------------------------------
Process finished with exit code 0