装饰者模式

/**接口定义一个方法
 * Created by Administrator on 2019/6/10.
 */
public interface Waiter {
    void  service();
}

/**子类实现接口的方法
 * Created by Administrator on 2019/6/10.
 */
public class Waitress implements Waiter {
    @Override
    public void service() {
        System.out.println("在服务。。。");
    }
}

/**装饰类实现接口
 * Created by Administrator on 2019/6/10.
 */
public class WaitreeWrap implements Waiter {

    //声明Waiter对象
    Waiter waiter=null;
    //在构造函数中有个有参数的方法
    public WaitreeWrap(Waiter waiter){
        this.waiter=waiter;
    }
    @Override
    public void service() {
        //在重写方法的基础添加额外的功能
        System.out.println("微笑");
        waiter.service();
    }
}

/**
 * Created by Administrator on 2019/6/10.
 */
public class Test {
    public static void main(String[] args) {
        WaitreeWrap ns=new
                WaitreeWrap(new Waitress());
        ns.service();
    }
}