观察者模式UML图与源代码

以下是UML图（注：Obsever接口，Observable类是java.util包下文件）：

 

源代码：Product

 

 import java.util.Observable;

 public class Product extends Observable{

     private String nameString;
     private double price;
     public Product(String nameString, double price) {
         super();
         this.nameString = nameString;
         this.price = price;
     }
     public void setNameString(String nameString) {
         if(!this.nameString.equals(nameString)){
         this.nameString = nameString;
         setChanged();
         }"white-space: pre;">
                 //Observable的方法
         notifyObservers(nameString);
     }
     public void setPrice(double price) {
         if (this.price!=price) {
             this.price = price;
             setChanged();
         }
         notifyObservers(price);
     }
 }

 

 NameObserver类：

 

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

 public class NameObserver implements Observer {

     public void update(Observable arg0, Object arg1) {
         if (arg1 instanceof String) {
             System.out.println("观察物" + arg0 + "的名称改为：" + arg1);
         }

     }
 }

 

 PriceObserver类：

 

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

 public class PriceObserver implements Observer {

     public void update(Observable arg0, Object arg1) {
         if (arg1 instanceof Double) {
             System.out.println("观察物"+arg0+"的价格变化为"+arg1);
         }
     }

 }

 

 Client类：

 

 public class Client {

     public static void main(String[] args) {
         Product product = new Product("电脑", 2000);
         PriceObserver priceObserver = new PriceObserver();
         NameObserver nameObserver = new NameObserver();
         product.addObserver(nameObserver);
         product.addObserver(priceObserver);
         product.setNameString("笔记本电脑");
         product.setPrice(5000);
     }
 }

 

 运行结果截图：