646
人物
【观察者模式】
/**
* Description:
* <br/>网站: <a href="https://www.crazyit.org">疯狂Java联盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public interface Observer
{
void update(Observable o , Object arg);
}
import java.util.ArrayList;
import java.util.List;
import java.util.Iterator;
/**
* Description:
* <br/>网站: <a href="https://www.crazyit.org">疯狂Java联盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public abstract class Observable
{
// 用一个List来保存该对象上所有绑定的事件监听器
List<Observer> observers =
new ArrayList<Observer>();
//定义一个方法，用于从该主题上注册观察者
public void registObserver(Observer o)
{
observers.add(o);
}
//定义一个方法，用于从该主题中删除观察者
public void removeObserver(Observer o)
{
observers.remove(o);
}
//通知该主题上注册的所有观察者
public void notifyObservers(Object value)
{
//遍历注册到该被观察者上的所有观察者
for (Iterator it = observers.iterator();
it.hasNext(); )
{
Observer o = (Observer)it.next();
//显式每个观察者的update方法
o.update(this , value);
}
}
}
import java.util.Iterator;
/**
* Description:
* <br/>网站: <a href="https://www.crazyit.org">疯狂Java联盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class Product extends Observable
{
//定义两个属性
private String name;
private double price;
//无参数的构造器
public Product(){}
public Product(String name , double price)
{
this.name = name;
this.price = price;
}
public String getName()
{
return name;
}
//当程序调用name的setter方法来修改Product的name属性时
//程序自然触发该对象上注册的所有观察者
public void setName(String name)
{
this.name = name;
notifyObservers(name);
}
public double getPrice()
{
return price;
}
//当程序调用price的setter方法来修改Product的price属性时
//程序自然触发该对象上注册的所有观察者
public void setPrice(double price)
{
this.price = price;
notifyObservers(price);
}
}
import javax.swing.JFrame;
import javax.swing.JLabel;
/**
* Description:
* <br/>网站: <a href="https://www.crazyit.org">疯狂Java联盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class NameObserver implements Observer
{
//实现观察者必须实现的update方法
public void update(Observable o , Object arg)
{
if (arg instanceof String )
{
//产品名称改变值在name中
String name = (String)arg;
//启动一个JFrame窗口来显示被观察对象的状态改变
JFrame f = new JFrame("观察者");
JLabel l = new JLabel("名称改变为：" + name);
f.add(l);
f.pack();
f.setVisible(true);
System.out.println("名称观察者:" +
o + "物品名称已经改变为: " + name);
}
}
}
/**
* Description:
* <br/>网站: <a href="https://www.crazyit.org">疯狂Java联盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class PriceObserver implements Observer
{
//实现观察者必须实现的update方法
public void update(Observable o , Object arg)
{
if(arg instanceof Double)
{
System.out.println("价格观察者:" +
o + "物品价格已经改变为: " + arg);
}
}
}
/**
* Description:
* <br/>网站: <a href="https://www.crazyit.org">疯狂Java联盟</a>
* <br/>Copyright (C), 2001-2012, Yeeku.H.Lee
* <br/>This program is protected by copyright laws.
* <br/>Program Name:
* <br/>Date:
* @author Yeeku.H.Lee kongyeeku@163.com
* @version 1.0
*/
public class PriceObserver implements Observer
{
//实现观察者必须实现的update方法
public void update(Observable o , Object arg)
{
if(arg instanceof Double)
{
System.out.println("价格观察者:" +
o + "物品价格已经改变为: " + arg);
}
}
}
最后更新：2017-04-04 07:03:36