java中的事件定义_Java中定义事件
我们在JFrame、awt或swing中了解过事件的概念。如MouseEvent, KeyEvent, WindowEvent。
JDK就像给我们提供了框架结构一样，提供了设计事件和监听的方法。
1.设计一个事件
import java.util.EventObject;
public class DemoEvent extends EventObject {
Object obj;
public DemoEvent(Object source)
{
super(source);
// TODO Auto-generated constructor stub
obj = source;
}
public Object getSource()
{
return obj;
}
public void say()
{
System.out.println("This is say method...");
}
}
2.设计事件源
import java.util.Enumeration;
import java.util.Vector;
//import java.util.*;
public class DemoSource
{
private Vector repository = new Vector();
DemoListener dl;
public DemoSource()
{
}
public void addDemoListener(DemoListener dl)//添加监听
{
repository.addElement(dl);
}
public void notifyDemoEvent()
{
Enumeration enum1 = repository.elements();
while(enum1.hasMoreElements())
{
dl = (DemoListener)enum1.nextElement();
dl.demoEvent(new DemoEvent(this));
}
}
}
3.设计监听接口
import java.util.EventListener;
public interface DemoListener extends EventListener {
public void demoEvent(DemoEvent dm);
}
4.定义3个监听器(三个监听器，监听到后说的内容区别开)
Listener1.java
public class Listener1 implements DemoListener
{
public void demoEvent(DemoEvent de)
{
System.out.println("Inside listener1...");
}
}
Listener2.java
package demo.listener;
public class Listener2 implements DemoListener
{
public void demoEvent(DemoEvent de)
{
System.out.println("Inside listener2...");
}
}
Listener3.java
package demo.listener;
public class Listener3 implements DemoListener
{
public void demoEvent(DemoEvent de)
{
System.out.println("Inside listener3...");
}
}
5.测试类
public class TestDemo
{
DemoSource ds;
public TestDemo()
{
try{
ds = new DemoSource();
Listener1 l1 = new Listener1();
Listener2 l2 = new Listener2();
Listener3 l3 = new Listener3();
ds.addDemoListener(l1);
ds.addDemoListener(l2);
ds.addDemoListener(l3);
ds.notifyDemoEvent();
}catch(Exception ex){ex.printStackTrace();}
}
public static void main(String args[])
{
new TestDemo();
}
}
测试结果是：
Inside listener1...
Inside listener2...
Inside listener3...