动态增加额外的功能

interface DPerson{
    void eat();
}

class DMan implements DPerson{

    @Override
    public void eat() {
        System.out.println("man eat");
    }
}

abstract class Decorator implements DPerson{
    protected DPerson person;

    public void setPerson(DPerson person) {
        this.person = person;
    }

    @Override
    public void eat() {
        person.eat();
    }
}

class ManDecotatorA extends Decorator{
    @Override
    public void eat() {
        super.eat();
        reEat();
        System.out.println("ManDecotatorA");
    }
    public void reEat(){
        System.out.println("eat one more");
    }
}

class ManDecotatorB extends Decorator{
    @Override
    public void eat() {
        super.eat();
        System.out.println("---------");
        System.out.println("ManDecotatorB");
    }
    public void reEat(){
        System.out.println("eat one more");
    }
}

public class DecoratorTest {
    public static void main(String[] args){
        DMan man =new DMan();
        ManDecotatorA a =new ManDecotatorA();
        ManDecotatorB b =new ManDecotatorB();

        a.setPerson(man);
        b.setPerson(a);
        b.eat();

    }
}