Java8向后兼容

toInstant()方法被添加到可用于将它们转换到新的日期时间的API原始日期和日历对象。使用ofInstant(Insant,ZoneId)方法得到一个LocalDateTime或ZonedDateTime对象。

让我们来看看他们的操作。

选择使用任何编辑器创建以下java程序在 C:/> JAVA

Java8Tester.java

import java.time.LocalDateTime;
import java.time.ZonedDateTime;
import java.util.Date;
import java.time.Instant;
import java.time.ZoneId;

public class Java8Tester {
   public static void main(String args[]){
      Java8Tester java8tester = new Java8Tester();
      java8tester.testBackwardCompatability(); 	  
   }

   public void testBackwardCompatability(){
      //Get the current date
      Date currentDate = new Date();
      System.out.println("Current date: " + currentDate);	  

      //Get the instant of current date in terms of milliseconds
      Instant now = currentDate.toInstant();
      ZoneId currentZone = ZoneId.systemDefault();

      LocalDateTime localDateTime = LocalDateTime.ofInstant(now, currentZone);
      System.out.println("Local date: " + localDateTime);	  

      ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(now, currentZone);
      System.out.println("Zoned date: " + zonedDateTime);	  
   }	
}

验证结果

使用javac编译器编译如下类

C:\JAVA>javac Java8Tester.java

现在运行Java8Tester看到的结果

C:\JAVA>java Java8Tester

看到结果。

Current date: Wed Dec 10 05:44:06 UTC 2014                               
Local date: 2014-12-10T05:44:06.635                                      
Zoned date: 2014-12-10T05:44:06.635Z[Etc/UTC]