最常用的四种设计模式

 1 abstract　class BallFactory{  
 2 protected　abstract Ball makeBall();　//Factory Method  
 3 }  
 4 class BasketballFact extends BallFactory{  
 5 public Ball makeBall(){　　　 //子类实现Factory Method决定实例化哪一个类的  
 6 　return new Basketball();  
 7 }  
 8 }  
 9 class FootballFact extends BallFactory{  
10 public Ball makeBall(){　　　//子类实现Factory Method决定实例化哪一个类的  
11 　return new Football();  
12 }  
13 }  
14 class　Basketball extends Ball{  
15 public void play(){  
16 　System.out.println("play the basketball");  
17 }  
18 }  
19 class Football extends Ball{  
20 public　void play(){  
21 　System.out.println("play the football");  
22 }  
23 }  
24 abstract class Ball{  
25 protected　abstract　void play();  
26 }  
27 public class test{  
28 public static void main(String[] args){  
29 　BallFactory ballFactory=new BasketballFact();  
30 　Ball basketball=ballFactory.makeBall();  
31 　basketball.play();  
32 　  
33 　ballFactory=new FootballFact();  
34 　Ball football=ballFactory.makeBall();  
35 　football.play();  
36 }  
37 }