一. 学习项目:咖啡馆订单系统
咖啡馆订单:
1)咖啡种类:Espresso,ShortBlack,LongBlack,Decaf
2)调料:Milk,Soy,Chocolate
3)扩展性好,改动方便,维护方便
1.一个差的解决方案:
饮品超类:
(1)<abstract>Drink
description
getDescription()
cost()
咖啡单品:
(1) Decaf
cost()
(2) ShortBlack
cost()
(3) LongBlack
cost()
(4) Espresso
cost()
添加调料咖啡:
(1)Espresso && Milk
cost()
(3)Espresso && Soy
cost()
(3)Espresso && Milk && Soy
cost()
...
...
拓展性很差,到时可能遇见类爆炸。。。
2. 一个较好的设计方案
饮品超类:
<abstract>Drink
desciprtion
milk
soy
chocolate
getDescription()
cost()
hasMilk()
setMilk()
hasSoy()
setSoy()
hasChocolate()
setChocolate()
咖啡单品:
(1) Decaf
cost()
(2) ShortBlack
cost()
(3) LongBlack
cost()
(4) Espresso
cost()
存在一些问题:
(1)增删调料种类
(2)添加多份问题
3.使用装饰者模式
了解装饰者模式
(1)装饰者模式就像打包的一个快递
1)主体:陶瓷 ,衣服
2)包装:报纸填充,塑料泡沫,纸盒,木盒
(2)Component:
(3)ConcreteComponent 和 Decorator
(4)装饰者模式:动态的将新的功能附加到对象上。在对象的扩展方面,它比继承更有弹性。
设计方案:
1.
<abstract>Drink
description
getDescription()
cost()
2.
Decorator
Drink obj
getDescription()
cost()
...
3.
咖啡单品:
(1) Decaf
cost()
(2) ShortBlack
cost()
(3) LongBlack
cost()
(4) Espresso
cost()
调料单品:
(1)Chocolate
getDescription()
cost()
(2)Milk
getDescription()
cost()
(3)Soy
getDescription()
cost()
代码实现:
(1) Drink
package com.java.keen.coffeebar;
//饮品类:描述,价格
public abstract class Drink {
public String description = "";
private float price = 0f;
public String getDescription() {
return description+" "+this.getPrice();
}
public void setDescription(String description) {
this.description = description;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
//花费是一个抽象方法,因为不知道顾客具体选喝啥
public abstract float cost();
}
(2)Decorator
package com.java.keen.coffeebar.decorator;
import com.java.keen.coffeebar.Drink;
public class Decorator extends Drink{
private Drink obj;
public Decorator(Drink obj) {
this.obj = obj;
}
@Override
public float cost() {
return super.getPrice() +obj.cost();
}
public String getDescription() {
return super.description+"+"+super.getPrice()+"&&"+obj.getDescription();
}
}
(3)Coffee
package com.java.keen.coffeebar.coffee;
import com.java.keen.coffeebar.Drink;
public class Coffee extends Drink {
@Override
public float cost() {
return super.getPrice();
}
}
(4)各种咖啡单品
//1.Decaf
package com.java.keen.coffeebar.coffee;
public class Decaf extends Coffee{
public Decaf() {
super.setDescription("Decaf");
super.setPrice(3.0f);
}
}
//2.Espresso
package com.java.keen.coffeebar.coffee;
public class Espresso extends Coffee{
public Espresso() {
super.setDescription("Espresso");
super.setPrice(4.0f);
}
}
//3.LongBlack
package com.java.keen.coffeebar.coffee;
public class LongBlack extends Coffee{
public LongBlack() {
super.setDescription("LongBlack");
super.setPrice(5.0f);
}
}
//4.ShortBlack
package com.java.keen.coffeebar.coffee;
public class ShortBlack extends Coffee{
public ShortBlack () {
super.setDescription("ShortBlack ");
super.setPrice(6.0f);
}
}
(5)各种调料单品:
//1.Chocolate
package com.java.keen.coffeebar.decorator;
import com.java.keen.coffeebar.Drink;
public class Chocolate extends Decorator{
public Chocolate(Drink obj) {
super(obj);
// TODO Auto-generated constructor stub
super.setDescription("Chocolate");
super.setPrice(3.0f);
}
}
//2.Milk
package com.java.keen.coffeebar.decorator;
import com.java.keen.coffeebar.Drink;
public class Milk extends Decorator{
public Milk(Drink obj) {
super(obj);
// TODO Auto-generated constructor stub
super.setDescription("milk");
super.setPrice(2.5f);
}
}
//3.Soy
package com.java.keen.coffeebar.decorator;
import com.java.keen.coffeebar.Drink;
public class Soy extends Decorator{
public Soy(Drink obj) {
super(obj);
// TODO Auto-generated constructor stub
super.setDescription("soy");
super.setPrice(1.5f);
}
}
(6)测试类
package com.java.keen.coffeebar;
import com.java.keen.coffeebar.coffee.*;
import com.java.keen.coffeebar.decorator.*;
public class CoffeeBar {
public static void main(String[] args) {
Drink order;
order = new Decaf();
System.out.println("order1 price: " +order.cost());
System.out.println("order1 desc : "+order.getDescription());
System.out.println("***************");
order = new LongBlack();
order = new Milk(order);
order =new Chocolate(order);
order =new Chocolate(order);
System.out.println("order2 price: " +order.cost());
System.out.println("order2 desc : "+order.getDescription());
}
}
output:
order1 price: 3.0
order1 desc : Decaf 3.0
***************
order2 price: 13.5
order2 desc : Chocolate+3.0&&Chocolate+3.0&&milk+2.5&&LongBlack 5.0
个人在极客学院的学习的笔记
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