Observer模式【二】

package observerDM;

import java.util.Observable;

public class ConcreteSubject extends Observable {

	public ConcreteSubject(String _name , float _price) {
		this.name = _name;
		this.price = _price;
		System.out.println("ConcreteSubject created:" + _name + "at" + _price);
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
		setChanged();
		notifyObservers(name);
	}
	public float getPrice() {
		return price;
	}
	public void setPrice(float price) {
		this.price = price;
		setChanged();
		notifyObservers(price);
	}

	private String name ;
	private float price ;
}

 

package observerDM;

import java.util.Observable;
import java.util.Observer;

public class NameObserver implements Observer {

	public NameObserver() {
		this.name = null ;
		System.out.println("NameObserver has created:Name is :" + this.name);
	}
	
	public void update(Observable o, Object arg) {
		
		if(arg instanceof String) {
			name = (String)arg;
			System.out.println("NameObserver has changed:Name is :" + name);
		}else {
			System.out.println("NameObserver :some other change to subject");
		}
	}
	
	private String name ;
}

 

package observerDM;

import java.util.Observable;
import java.util.Observer;

public class PriceObserver implements Observer {

	public PriceObserver() {
		this.price = 0 ;
		System.out.println("PriceObserver has created : Price is :" + price);
	}
	
	public void update(Observable o, Object arg) {
		if(arg instanceof Float) {
			price = ((Float)arg).floatValue();
			System.out.println("PriceObserver has changed:Price is :" + price);
		}else {
			System.out.println("PriceObserver :some other change to subject");
		}
	}
	
	private float price ;
}

 

package observerDM;

public class TestObservers {
	
	public static void main(String[] args){
		
		ConcreteSubject sub = new ConcreteSubject("Com pops",(float)1.30);
		
		NameObserver name = new NameObserver();
		PriceObserver price = new PriceObserver();
		
		sub.addObserver(name);
		sub.addObserver(price);
		
		sub.setName("Frosted Flakes");
		sub.setPrice((float)1.40);
		
		sub.setPrice((float)2.03);
		sub.setName("helloWorld");
	}
}

 

评论

1 楼 csdn_zuoqiang 2010-08-24  

ConcreteSubject created:Com popsat1.3
NameObserver has created:Name is :null
PriceObserver has created : Price is :0.0
PriceObserver :some other change to subject
NameObserver has changed:Name is :Frosted Flakes
PriceObserver has changed:Price is :1.4
NameObserver :some other change to subject
PriceObserver has changed:Price is :2.03
NameObserver :some other change to subject
PriceObserver :some other change to subject
NameObserver has changed:Name is :helloWorld