java装饰者模式如何使用

public class HelloWorld {
    public static void main(String[] args) {
        //点一份炒饭
        FastFood food = new FriedRice();
        //花费的价格
        System.out.println(food.getDesc() + " " + food.cost() + "元");
 
        System.out.println("========");
 
        //点一份加鸡蛋的炒饭
        FastFood food1 = new FriedRice();
        food1 = new Egg(food1);
        //花费的价格
        System.out.println(food1.getDesc() + " " + food1.cost() + "元");
 
        System.out.println("========");
 
        //点一份加培根的炒面
        FastFood food2 = new FriedNoodles();
        food2 = new Bacon(food2);
        //花费的价格
        System.out.println(food2.getDesc() + " " + food2.cost() + "元");
    }
}
 
// 快餐抽象类
abstract class FastFood {
    private float price;
    private String desc;
 
    public FastFood() {}
 
    public FastFood(float price, String desc) {
        this.price = price;
        this.desc = desc;
    }
 
    public float getPrice() {
        return price;
    }
 
    public void setPrice(float price) {
        this.price = price;
    }
 
    public String getDesc() {
        return desc;
    }
 
    public void setDesc(String desc) {
        this.desc = desc;
    }
 
    // 获取价格
    public abstract float cost();
}
 
// 炒饭
class FriedRice extends FastFood {
    public FriedRice() {
        super(10, "炒饭");
    }
 
    @Override
    public float cost() {
        return getPrice();
    }
}
 
// 炒面
class FriedNoodles extends FastFood {
    public FriedNoodles() {
        super(12, "炒面");
    }
 
    @Override
    public float cost() {
        return getPrice();
    }
}
 
// 配料
abstract class Garnish extends FastFood {
    private FastFood fastFood;
 
    public FastFood getFastFood() {
        return fastFood;
    }
 
    public void setFastFood(FastFood fastFood) {
        this.fastFood = fastFood;
    }
 
    public Garnish(FastFood fastFood, float price, String desc) {
        super(price, desc);
        this.fastFood = fastFood;
    }
}
 
// 鸡蛋配料
class Egg extends Garnish {
    public Egg(FastFood fastFood) {
        super(fastFood, 1, "鸡蛋");
    }
 
    @Override
    public float cost() {
        return getPrice() + getFastFood().getPrice();
    }
 
    @Override
    public String getDesc() {
        return super.getDesc() + getFastFood().getDesc();
    }
}
 
//培根配料
class Bacon extends Garnish {
    public Bacon(FastFood fastFood) {
        super(fastFood,2,"培根");
    }
 
    @Override
    public float cost() {
        return getPrice() + getFastFood().getPrice();
    }
 
    @Override
    public String getDesc() {
        return super.getDesc() + getFastFood().getDesc();
    }
}