HELLOWORLD级事件属性监听小技巧,随便写了点测试代码

王朝java/jsp·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

首先,定义一个基类,负责加入监听者,

package net.cafe;

import java.beans.PropertyChangeSupport;

import java.beans.PropertyChangeListener;

/**

* Created by IntelliJ IDEA.

* User: JJYAO

* Date: 2004-11-1

* Time: 23:01:56

* To change this template use File | Settings | File Templates.

*/

public class BaseEventBean {

protected PropertyChangeSupport pcs;

public void addPropertyChangeListener(PropertyChangeListener listener){

if(pcs == null){

pcs = new PropertyChangeSupport(this);

}

pcs.addPropertyChangeListener(listener);

}

public void removeChangeListener(PropertyChangeListener listener) {

if(pcs != null){

pcs.removePropertyChangeListener(listener);

}

}

}

一个POJO继承这个类,并在SET方法里添加触发事件的方法

package net.cafe;

/**

* Created by IntelliJ IDEA.

* User: JJYAO

* Date: 2004-11-1

* Time: 23:15:34

* To change this template use File | Settings | File Templates.

*/

public class FoolBean extends BaseEventBean {

private String userName;

private String password;

public String getPassword() {

return password;

}

public void setPassword(String newPassword) {

String oldPassword = password;

this.password = newPassword;

pcs.firePropertyChange("password",oldPassword,password);

}

public String getUserName() {

return userName;

}

public void setUserName(String userName) {

this.userName = userName;

}

}

属性监听者

package net.cafe;

import java.beans.PropertyChangeListener;

import java.beans.PropertyChangeEvent;

/**

* Created by IntelliJ IDEA.

* User: JJYAO

* Date: 2004-11-1

* Time: 23:12:33

* To change this template use File | Settings | File Templates.

*/

public class Listener implements PropertyChangeListener {

public void propertyChange(PropertyChangeEvent evt) {

System.out.println("==========old value=========" + evt.getOldValue()) ;

System.out.println("==========new Value========" + evt.getNewValue());

}

}

测试代码

package net.cafe;

/**

* Created by IntelliJ IDEA.

* User: JJYAO

* Date: 2004-11-1

* Time: 23:24:28

* To change this template use File | Settings | File Templates.

*/

public class BeanEventTest {

public static void main(String[] args){

FoolBean bean = new FoolBean();

bean.addPropertyChangeListener(new Listener());

bean.setPassword("22222");

bean.setPassword("33333");

}

}

BTW,SUN的java.beans.*包含了大多空包,这些方法都需要自己扩展,我们完全不需要用它定义的方法名

上面的例子完全可以用自己的方法来实现,

 
 
 
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