29.JDK8开始新增日期API：Peroid、Duration

Duration/Period

Period

• 在Java8中，我们可以使用以下类来计算日期间隔差异：java.time.Period

  比如一个日期到另一个日期相隔了多少天

• 主要是Period类方法getYear()，getMonth() 和 getDays() 来计算，只能精确到年月日

• 用于LocalDate之间的比较

  LocalDate today = LocalDate.now();
  System.out.println(today);
  LocalDate birthDay = LocalDate.of(1995, 1, 11);
  System.out.println(birthDay);
  Period period = Period.between(birthDate, today);
  System.out.println("年龄：%d年%d月%d日", period.getYears(), period.getMonths(), period.getDays());
  

• 测试代码：

  package com.java.jdk8time_update;
  
  import java.time.LocalDate;
  import java.time.Period;
  
  public class PeriodTest {
      public static void main(String[] args) {
          // 当前本地 年月日
          LocalDate today = LocalDate.now();
          System.out.println(today);
  
          // 生日的年月日
          LocalDate birthDate = LocalDate.of(2000,12,16);
          System.out.println(birthDate);
          
          // 第二个参数减去第一个参数，返回一个间隔对象
          Period period = Period.between(birthDate, today);
          
          // 从间隔对象中获取年，获取月，获取日
          System.out.println(period.getYears());
          System.out.println(period.getMonths());
          System.out.println(period.getDays());
      }
  }
  
  

Duration

• 在Java8中，我们可以使用以下类来计算时间间隔差异：java.time.Duration

• 提供了使用基于时间的值测量时间量的方法

• 用于LocalDateTime之间的比较，也可以用于Instant之间的比较

  package com.java.jdk8time_update;
  
  
  import java.time.Duration;
  import java.time.LocalDateTime;
  
  public class DurationTest {
      public static void main(String[] args) {
          // 当前本地 年月日
          LocalDateTime today = LocalDateTime.now();
          System.out.println(today);
  
          // 生日的年月日
          LocalDateTime birthDate = LocalDateTime.of(2000, 12, 16, 8, 32, 57);
          System.out.println(birthDate);
  
          Duration duration = Duration.between(birthDate, today);  //参数二减去参数一
          System.out.println("隔了多少天" + duration.toDays());
          System.out.println("隔了多少时" + duration.toHours());
          System.out.println("隔了多少分" + duration.toMinutes());
          System.out.println("隔了多少秒" + duration.toMillis());
          System.out.println("隔了多少纳秒" + duration.toNanos());
  
      }
  }
  
  

• Duration：用于计算两个“时间”间隔
• Period：用于计算两个“日期”间隔

ChronoUnit

• 包：java.time.temporal.ChronoUnit

• ChronoUnit类可用于在单个时间单位内测量一段时间，这个工具类是最全的了，可以用于比较所有的时间单位

  package com.java.jdk8time_update;
  
  import java.time.LocalDateTime;
  import java.time.temporal.ChronoUnit;
  
  public class ChronoUnitTest {
      public static void main(String[] args) {
          // 本地日期时间对象
          LocalDateTime today = LocalDateTime.now();
          System.out.println(today);
  
          LocalDateTime birthDate = LocalDateTime.of(2000,12,16,20,32);
          System.out.println(birthDate);
  
          // ChronoUnit通过点调用它的对象(查看源码可知通过枚举实现)，使用该对象调用between
          
          System.out.println("相差的年数：" + ChronoUnit.YEARS.between(birthDate,today));
          System.out.println("相差的月数：" + ChronoUnit.MONTHS.between(birthDate,today));
          System.out.println("相差的周数：" + ChronoUnit.WEEKS.between(birthDate, today));
          System.out.println("相差的天数：" + ChronoUnit.DAYS.between(birthDate,today));
          System.out.println("相差的时数：" + ChronoUnit.HOURS.between(birthDate,today));
          System.out.println("相差的分数：" + ChronoUnit.MINUTES.between(birthDate,today));
          System.out.println("相差的秒数：" + ChronoUnit.SECONDS.between(birthDate,today));
          System.out.println("相差的毫秒数：" + ChronoUnit.MILLIS.between(birthDate,today));
          System.out.println("相差的微秒数：" + ChronoUnit.MICROS.between(birthDate,today));
          System.out.println("相差的纳秒数：" + ChronoUnit.NANOS.between(birthDate,today));
          System.out.println("相差的半天数：" + ChronoUnit.HALF_DAYS.between(birthDate,today));
          System.out.println("相差的十年数：" + ChronoUnit.DECADES.between(birthDate,today));
          System.out.println("相差的世纪数：" + ChronoUnit.CENTURIES.between(birthDate,today));
          System.out.println("相差的千年数：" + ChronoUnit.MILLENNIA.between(birthDate,today));
          System.out.println("相差的纪元数：" + ChronoUnit.ERAS.between(birthDate,today));
  
      }
  }