Date类

import java.util.Date;
public class TestDate {
	public static void main(String[] args){
	Date date=new Date();  //无参fastTime=当前时间
	long t = System.currentTimeMillis();
	System.out.println(t);
	System.out.println(date);
	
	Date a =new Date(1000);
	System.out.println(a);
	System.out.println(a.toGMTString());
	System.out.println(a.getTime());//返回fastTime
	a.setTime(232465465);
	System.out.println(a.toString());
	System.out.println(a.toLocaleString());
	/*
	 * public void setTime(long time){    重新设置fastTime
	 * fastTime=time; 
	 * cdate=null;
	 * }
	 */
	}
}

对Date类的测试

/*源码*/
    public Date() {
        this(System.currentTimeMillis());
    }

    public Date(long date) {
        fastTime = date;
    }

构造器，无参的时候，调用另一个构造器，Date date=new Date(); 时间是当前时间与1970年1.1日0:00的毫秒数差值

@param date the milliseconds since January 1, 1970, 00:00:00 GMT.

public long getTime() {
return getTimeImpl();
}

/* private final long getTimeImpl() {

if (cdate != null && !cdate.isNormalized()) {
normalize();
}
return fastTime;
}

public void setTime(long time) {
fastTime = time;
cdate = null;
}

public boolean before(Date when) {
return getMillisOf(this) < getMillisOf(when);
}

public boolean after(Date when) {
return getMillisOf(this) > getMillisOf(when);
}

befor() 和after()方法就是比较fastTime值的大小，Date d1=new Date(1000); Date d2=new Date(1001); blean a=(d1.getTime()<d2.getTime());

public boolean equals(Object obj) {
return obj instanceof Date && getTime() == ((Date) obj).getTime();
}

重写了Object的equals()方法，先判断是不是属于Date类的对象，与上fastTime值的比较

public boolean equals(Object obj) {
return (this == obj);
}

Date类的核心就是1970.01.01.00:00这个时间点

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