接口实际应用-工厂代理模式

 1 package cn.demo;
 2 interface Subject{
 3     public void get();
 4 }
 5 class RealSubject implements Subject{
 6     public void get(){
 7         System.out.println("吃饭");
 8     } 
 9 }
10 class Factory{
11     public static Subject getInstance(String charName){
12         if("real".equals(charName)){
13             return new RealSubject();
14         }
15         return null;
16     }
17 }
18 class Proxy implements Subject{
19     private Subject sub;
20     public Proxy(){
21         this.sub = Factory.getInstance("real");
22     }
23     public void prepare(){
24         System.out.println("饭前洗手");
25     }
26     public void get(){
27         this.prepare();
28         this.sub.get();
29         this.after();
30     }
31     public void after(){
32         System.out.println("收拾餐桌");
33     }
34 }
35 public class Test{
36     public static void main(String args[]){
37         Subject s =new Proxy();
38         s.get();
39     }
40 }