接口实际应用-工厂代理模式

package cn.demo;
interface Subject{
    public void get();
}
class RealSubject implements Subject{
    public void get(){
        System.out.println("吃饭");
    } 
}
class Factory{
    public static Subject getInstance(String charName){
        if("real".equals(charName)){
            return new RealSubject();
        }
        return null;
    }
}
class Proxy implements Subject{
    private Subject sub;
    public Proxy(){
        this.sub = Factory.getInstance("real");
    }
    public void prepare(){
        System.out.println("饭前洗手");
    }
    public void get(){
        this.prepare();
        this.sub.get();
        this.after();
    }
    public void after(){
        System.out.println("收拾餐桌");
    }
}
public class Test{
    public static void main(String args[]){
        Subject s =new Proxy();
        s.get();
    }
}

结果：

饭前洗手
吃饭
收拾餐桌