装饰者模式(Decorator Pattern)

类图

ICar.java

public interface ICar {
    //汽车有跑的功能
    public void run();
}

Honda.java

public class Honda implements ICar {

    @Override
    public void run() {
        System.out.println("本田有跑的功能");
    }
}

Volvo.java

public class Volvo implements ICar{

    @Override
    public void run() {
        System.out.println("沃尔沃有跑的功能");
    }
}

MusicDecorator.java

public abstract class MusicDecorator 
        implements ICar{  //实现原有的接口

    protected ICar iCar;  //持有原有的接口

    public MusicDecorator(ICar iCar){
        this.iCar = iCar;
    }

    @Override
    public void run() {
        iCar.run();
    }
}

MusicDecoratorImpl.java

//装饰者具体实现
public class MusicDecoratorImpl extends MusicDecorator {

    public MusicDecoratorImpl(ICar iCar){
        super(iCar);
    }

    @Override
    public void run() {
       iCar.run();
       playMuisc();
    }

    public void playMuisc(){
        System.out.println("播放音乐");
    }
}

TVDecorator.java

public abstract class TVDecorator implements ICar{

    protected ICar iCar;

    public TVDecorator(ICar iCar){
        this.iCar = iCar;
    }

    @Override
    public void run() {
        iCar.run();
    }
}

TVDecoratorImpl.java

public class TVDecoratorImpl extends TVDecorator {
    public TVDecoratorImpl(ICar iCar) {
        super(iCar);
    }

    @Override
    public void run() {
        iCar.run();
        playTv();
    }

    public void playTv(){
        System.out.println("播放电视");
    }
}

TestMain.java

public class TestMain {

    //车只有跑的功能
    @Test
    public void hondaRunTest(){
        ICar iCar = new Honda();
        iCar.run();
    }


    //为本田汽车添加音乐和看电视功能
    @Test
    public void testHonda(){

        ICar honda = new Honda();  //本田汽车
        honda = new MusicDecoratorImpl(honda);   //音乐功能
        honda = new TVDecoratorImpl(honda);   //看电视功能
        honda.run();
    }

    //为沃尔沃汽车添加音乐和看电视功能
    @Test
    public void testVolvo(){
        ICar volvo = new Volvo();
        volvo = new MusicDecoratorImpl(volvo);
        volvo = new TVDecoratorImpl(volvo);
        volvo.run();
    }
}

输出

本田有跑的功能
播放音乐
播放电视