interface Isubject{

    void buyAJ();

}

class realsubject implements Isubject{

    public void buyAJ(){

        System.out.println("买一双AJ，在代购平台付款");

    }

}

class proxysubject implements Isubject{

   private Isubject subject;

   public    proxysubject(Isubject subject){

        this.subject=subject;

    }

   public void beforebuy(){

            System.out.println("去美国AJ专卖店排队抽号");

        }

public void afterbuy(){

    System.out.println("快递到客户手上");

    }

    public void buyAJ(){

        beforebuy();

         subject. buyAJ();

        afterbuy();

    }

}

public class Test{

    public static void main(String[] args) {

        Isubject subject=new proxysubject(new realsubject() );

        subject.buyAJ();

    }

}