java23设计模式装饰者模式
1.装饰者模式原理
1) 装饰者模式就像打包一个快递 主体:比如:陶瓷、衣服 (Component) // 被装饰者 包装:比如:报纸填充、塑料泡沫、纸板、木板(Decorator)
2) Component 主体:比如类似前面的 Drink
3) ConcreteComponent 和 Decorator ConcreteComponent:具体的主体, 比如前面的各个单品咖啡
4) Decorator: 装饰者,比如各调料. 在如图的 Component 与 ConcreteComponent 之间,如果 ConcreteComponent 类很多,还可以设计一个缓冲层,将 共有的部分提取出来,抽象层一个类。
2.装饰者模式解决星巴克咖啡订单
![](https://img2020.cnblogs.com/blog/1064237/202112/1064237-20211229170328080-683575204.png)
3.代码展示
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public abstract class Drink { public String des; // 描述 private float price = 0.0f; public String getDes() { return des; } public void setDes(String des) { this.des = des; } public float getPrice() { return price; } public void setPrice(float price) { this.price = price; } //计算费用的抽象方法 //子类来实现 public abstract float cost(); }
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public class Coffee extends Drink { @Override public float cost() { // TODO Auto-generated method stub return super.getPrice(); } }
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public class ShortBlack extends Coffee{ public ShortBlack() { setDes(" shortblack "); setPrice(4.0f); } }
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public class LongBlack extends Coffee { public LongBlack() { setDes(" longblack "); setPrice(5.0f); } }
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public class Espresso extends Coffee { public Espresso() { setDes(" 意大利咖啡 "); setPrice(6.0f); } }
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public class DeCaf extends Coffee { public DeCaf() { setDes(" 无因咖啡 "); setPrice(1.0f); } }
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public class Decorator extends Drink { private Drink obj; public Decorator(Drink obj) { //组合 // TODO Auto-generated constructor stub this.obj = obj; } @Override public float cost() { // TODO Auto-generated method stub // getPrice 自己价格 return super.getPrice() + obj.cost(); } @Override public String getDes() { // TODO Auto-generated method stub // obj.getDes() 输出被装饰者的信息 return des + " " + getPrice() + " && " + obj.getDes(); } }
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//具体的Decorator, 这里就是调味品 public class Chocolate extends Decorator { public Chocolate(Drink obj) { super(obj); setDes(" 巧克力 "); setPrice(3.0f); // 调味品 的价格 } }
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public class Milk extends Decorator { public Milk(Drink obj) { super(obj); // TODO Auto-generated constructor stub setDes(" 牛奶 "); setPrice(2.0f); } }
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public class Soy extends Decorator{ public Soy(Drink obj) { super(obj); // TODO Auto-generated constructor stub setDes(" 豆浆 "); setPrice(1.5f); } }
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public class CoffeeBar { public static void main(String[] args) { // TODO Auto-generated method stub // 装饰者模式下的订单:2份巧克力+一份牛奶的LongBlack // 1. 点一份 LongBlack Drink order = new LongBlack(); System.out.println("费用1=" + order.cost()); System.out.println("描述=" + order.getDes()); // 2. order 加入一份牛奶 order = new Milk(order); System.out.println("order 加入一份牛奶 费用 =" + order.cost()); System.out.println("order 加入一份牛奶 描述 = " + order.getDes()); // 3. order 加入一份巧克力 order = new Chocolate(order); System.out.println("order 加入一份牛奶 加入一份巧克力 费用 =" + order.cost()); System.out.println("order 加入一份牛奶 加入一份巧克力 描述 = " + order.getDes()); // 3. order 加入一份巧克力 order = new Chocolate(order); System.out.println("order 加入一份牛奶 加入2份巧克力 费用 =" + order.cost()); System.out.println("order 加入一份牛奶 加入2份巧克力 描述 = " + order.getDes()); System.out.println("==========================="); Drink order2 = new DeCaf(); System.out.println("order2 无因咖啡 费用 =" + order2.cost()); System.out.println("order2 无因咖啡 描述 = " + order2.getDes()); order2 = new Milk(order2); System.out.println("order2 无因咖啡 加入一份牛奶 费用 =" + order2.cost()); System.out.println("order2 无因咖啡 加入一份牛奶 描述 = " + order2.getDes()); } }