设计模式装饰器模式

Z时代
2024-01-10
分类：综合

概念理解：我早上需要吃早饭，今天吃鸡蛋，明天喝牛奶，在吃鸡蛋+ 牛奶，如果用简单的代码实现，关鸡蛋+牛奶，两种情况，我需要枚举3个场景，如果需要的东西叠加，枚举也跟着递增，所以产生了装饰器模式。先来看代码，在来理解概念

定义接口

//吃饭， 定义了全部的组件接口
public interface EatFoodComponen {
    public void eatFood();}

接口的具体实现、

//具体的吃饭行为，需要被装饰器装饰的原始类
public class EatFoodConcreteComponent implements EatFoodComponen {
    @Override
    public void eatFood() {
        System.out.println("每天早上都要吃饭");
    }}

装饰类

//装饰器
public class Egg implements EatFoodComponen {
    private EatFoodComponen eatFoodComponen;
    public Egg(EatFoodComponen eatFoodComponen) {
        this.eatFoodComponen = eatFoodComponen;
    }
    @Override
    public void eatFood() {
        eatFoodComponen.eatFood();
        System.out.println("吃鸡蛋");
    }
}
public class Milk implements EatFoodComponen {
    private EatFoodComponen eatFoodComponen;
    public Milk(EatFoodComponen eatFoodComponen) {
        this.eatFoodComponen = eatFoodComponen;
    }
    @Override
    public void eatFood() {
        eatFoodComponen.eatFood();
        System.out.println("喝牛奶");
    }}

测试类

public class Clinet {
    public static void main(String[] args) {
        EatFoodComponen componen = new EatFoodConcreteComponent();
        System.out.println("第一天想吃");
        EatFoodComponen myCom = new Egg(componen);
        myCom.eatFood();
        System.out.println("第二天想吃");
        myCom = new Milk(new Egg(componen));
        myCom.eatFood();
    }}