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<DemoListener> 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...