面向对象系统分析与设计_装饰器模式.ppt

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1、06 一月 2023Neusoft Computer Science and Technology Department copy right1OO System Analysis&Design【The Decorator Pattern】06 一月 2023Neusoft Computer Science and Technology Department copy right2Enjoy coffee06 一月 2023Neusoft Computer Science and Technology Department copy right3Our job is:lTo help Star

2、buzz Coffee Caf to update their ordering system.06 一月 2023Neusoft Computer Science and Technology Department copy right4The goal is tolCompute the cost of the beverage;lGive the description of the beverage;06 一月 2023Neusoft Computer Science and Technology Department copy right5Coffee with layers06 一

3、月 2023Neusoft Computer Science and Technology Department copy right6Starbuzz CoffeelCoffeeslHouse Blend$0.89lDark Roast$0.99lDecaf$1.05lEspresso$1.99lCondimentslSteamed Milk$0.10lMocha$0.20lSoy$0.15lWhip$0.1006 一月 2023Neusoft Computer Science and Technology Department copy right7Class diagram:BaseoB

4、everage是所有饮料的基类；cost()是抽象方法，所有子类都需要定义它们自己的cost()实现来返回特定饮料的价钱；description变量也是在子类里赋值的，表示特定饮料的描述信息，getDescription()方法可以返这个描述。06 一月 2023Neusoft Computer Science and Technology Department copy right806 一月 2023Neusoft Computer Science and Technology Department copy right9o除了咖啡以为，还提供丰富的调味品，比如：炼乳、巧克力、砂糖、牛奶等

5、，而且这些调味品也是要单独按份收费的，所以调味品也是订单系统中重要的一部分。06 一月 2023Neusoft Computer Science and Technology Department copy right10改进后的Beverage基类06 一月 2023Neusoft Computer Science and Technology Department copy right1106 一月 2023Neusoft Computer Science and Technology Department copy right12Class diagram:Condiments06 一月

6、 2023Neusoft Computer Science and Technology Department copy right13Class diagram:complete06 一月 2023Neusoft Computer Science and Technology Department copy right14The Decorator PatternlThe Decorator Pattern attaches additional responsibilities to an object dynamically.Decorators provide a flexible a

7、lternative to subclassing for extending functionality.Class diagram for Decorator06 一月 2023Neusoft Computer Science and Technology Department copy right15oComponent（被装饰对象基类）（被装饰对象基类）n 定义对象的接口，可以给这些对象动态增加职责；oConcreteComponent（具体被装饰对象）（具体被装饰对象）n定义具体的对象，Decorator可以给它增加额外的职责；oDecorator（装饰者抽象类）（装饰者抽象类）n维

8、护一个指向Component实例的引用，并且定义了与Component一致的接口；oConcreteDecorator（具体装饰者）（具体装饰者）n具体的装饰对象，给内部持有的具体被装饰对象增加具体的职责；06 一月 2023Neusoft Computer Science and Technology Department copy right16顺序图06 一月 2023Neusoft Computer Science and Technology Department copy right17咖啡的类图06 一月 2023Neusoft Computer Science and Technology Department copy right1806 一月 2023Neusoft Computer Science and Technology Department copy right19Class is overCongratulations!