1，首先新建最基本的抽象类，这个类在以后作为其他对象new的结果进行了返回

public abstract class ABattercake {
    protected abstract String getDesc();
    protected abstract int cost();

}

2，新建第二个副加的抽象类，这个抽象类呢，是继承了第一套的抽象的类

public abstract class AbstractDecorator extends ABattercake {
    private ABattercake aBattercake;

    public AbstractDecorator(ABattercake aBattercake) {
        this.aBattercake = aBattercake;
    }

    protected abstract void doSomething();

    @Override
    protected String getDesc() {
        return this.aBattercake.getDesc();
    }

    @Override
    protected int cost() {
        return this.aBattercake.cost();
    }
}

3，写实践类，首先写主题，煎饼这个类

public class Battercake extends ABattercake {
    @Override
    protected String getDesc() {
        return "煎饼";
    }

    @Override
    protected int cost() {
        return 8;
    }
}

4，写鸡蛋这个类，这个类是继承了副加的抽象类

public class EggDecorator extends AbstractDecorator {
    public EggDecorator(ABattercake aBattercake) {
        super(aBattercake);
    }

    @Override
    protected void doSomething() {

    }

    @Override
    protected String getDesc() {
        return super.getDesc()+" 加一个鸡蛋";
    }

    @Override
    protected int cost() {
        return super.cost()+1;
    }
}

香肠类

public class SausageDecorator extends AbstractDecorator{
    public SausageDecorator(ABattercake aBattercake) {
        super(aBattercake);
    }

    @Override
    protected void doSomething() {

    }

    @Override
    protected String getDesc() {
        return super.getDesc()+" 加一根香肠";
    }

    @Override
    protected int cost() {
        return super.cost()+2;
    }
}

观察这个类，里面的构造函数，是使用了最基础的那个类了

5，写测试的类

public class Test {
    public static void main(String[] args) {
        ABattercake aBattercake;
        aBattercake = new Battercake();
        aBattercake = new EggDecorator(aBattercake);
        aBattercake = new EggDecorator(aBattercake);
        aBattercake = new SausageDecorator(aBattercake);

        System.out.println(aBattercake.getDesc()+" 销售价格:"+aBattercake.cost());

    }
}

仔细观察这个类，发现这个抽象的方法多次的进行了调用。