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notes/设计模式.md
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notes/设计模式.md
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<!-- GFM-TOC -->
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* [<EFBFBD><EFBFBD> 1 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD>](#<EFBFBD><EFBFBD>-1-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD>)
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* [<EFBFBD><EFBFBD> 2 <EFBFBD><EFBFBD> <20>۲<EFBFBD><DBB2><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-2-<EFBFBD><EFBFBD>-<2D>۲<EFBFBD><DBB2><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 3 <EFBFBD><EFBFBD> װ<><D7B0>ģʽ](#<EFBFBD><EFBFBD>-3-<EFBFBD><EFBFBD>-װ<><D7B0>ģʽ)
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* [<EFBFBD><EFBFBD> 4 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-4-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD>ģʽ)
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* [4.1 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>](#41-<EFBFBD><EFBFBD><EFBFBD><EFBFBD>)
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* [4.2 <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#42-<2D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [4.3 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#43-<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 5 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-5-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 6 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-6-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 7 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-7-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [7.1 <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#71-<2D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [7.2 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#72-<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 8 <EFBFBD><EFBFBD> ģ<>巽<EFBFBD><E5B7BD>ģʽ](#<EFBFBD><EFBFBD>-8-<EFBFBD><EFBFBD>-ģ<>巽<EFBFBD><E5B7BD>ģʽ)
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* [<EFBFBD><EFBFBD> 9 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-9-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [9.1 <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#91-<2D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [9.2 Java <EFBFBD><EFBFBD><EFBFBD>õĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>](#92-java-<EFBFBD><EFBFBD><EFBFBD>õĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>)
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* [9.3 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ](#93-<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 10 <EFBFBD><EFBFBD> ״̬ģʽ](#<EFBFBD><EFBFBD>-10-<EFBFBD><EFBFBD>-״̬ģʽ)
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* [<EFBFBD><EFBFBD> 11 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-11-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD>ģʽ)
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* [<EFBFBD><EFBFBD> 12 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-12-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD>ģʽ)
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* [第 1 章 设计模式入门](#第-1-章-设计模式入门)
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* [第 2 章 观察者模式](#第-2-章-观察者模式)
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* [第 3 章 装饰模式](#第-3-章-装饰模式)
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* [第 4 章 工厂模式](#第-4-章-工厂模式)
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* [4.1 简单工厂](#41-简单工厂)
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* [4.2 工厂方法模式](#42-工厂方法模式)
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* [4.3 抽象工厂模式](#43-抽象工厂模式)
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* [第 5 章 单件模式](#第-5-章-单件模式)
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* [第 6 章 命令模式](#第-6-章-命令模式)
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* [第 7 章 适配器模式与外观模式](#第-7-章-适配器模式与外观模式)
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* [7.1 适配器模式](#71-适配器模式)
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* [7.2 外观模式](#72-外观模式)
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* [第 8 章 模板方法模式](#第-8-章-模板方法模式)
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* [第 9 章 迭代器和组合模式](#第-9-章-迭代器和组合模式)
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* [9.1 迭代器模式](#91-迭代器模式)
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* [9.2 Java 内置的迭代器](#92-java-内置的迭代器)
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* [9.3 组合模式](#93-组合模式)
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* [第 10 章 状态模式](#第-10-章-状态模式)
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* [第 11 章 代理模式](#第-11-章-代理模式)
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* [第 12 章 复合模式](#第-12-章-复合模式)
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* [12.1 MVC](#121-mvc)
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* [<EFBFBD><EFBFBD> 13 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<C4A3>ദ](#<EFBFBD><EFBFBD>-13-<EFBFBD><EFBFBD>-<2D><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<C4A3>ദ)
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* [<EFBFBD><EFBFBD> 14 <EFBFBD><EFBFBD> ʣ<>µ<EFBFBD>ģʽ](#<EFBFBD><EFBFBD>-14-<EFBFBD><EFBFBD>-ʣ<>µ<EFBFBD>ģʽ)
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* [第 13 章 与设计模式相处](#第-13-章-与设计模式相处)
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* [第 14 章 剩下的模式](#第-14-章-剩下的模式)
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<!-- GFM-TOC -->
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# <20><> 1 <20><> <20><><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD>
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**1. <20><><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD>**
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# 第 1 章 设计模式入门
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD>Ǵ<EFBFBD><EFBFBD>룬<EFBFBD><EFBFBD><EFBFBD>ǽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ѧϰ<EFBFBD><EFBFBD><EFBFBD>е<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>鸴<EFBFBD>á<EFBFBD>
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**1. 设计模式概念**
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ӵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD>ʻ㣬<EFBFBD>ڹ<EFBFBD>ͨʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ø<EFBFBD><EFBFBD>ٵĴʻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ۣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҳ<EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD>˽<EFBFBD><EFBFBD>ײ<EFBFBD>ϸ<EFBFBD>ڡ<EFBFBD>
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设计模式不是代码，而是解决问题的方案，学习现有的设计模式可以做到经验复用。
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**2. <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
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拥有设计模式词汇，在沟通时就能用更少的词汇来讨论，并且不需要了解底层细节。
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<EFBFBD><EFBFBD><EFBFBD>Ʋ<EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ѽ<EFBFBD><EFBFBD>ӵ<EFBFBD>в<EFBFBD>ͬ<EFBFBD>Ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͷ<EFBFBD><EFBFBD>з<EFBFBD>ʽ<EFBFBD><EFBFBD>
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**2. 问题描述**
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**3. <20><><EFBFBD><EFBFBD>ʵ<EFBFBD>ַ<EFBFBD><D6B7><EFBFBD>**
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设计不同种类的鸭子拥有不同的叫声和飞行方式。
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ʹ<EFBFBD>ü̳еĽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>£<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ַ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ã<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ѽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD>ķ<EFBFBD><EFBFBD>з<EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ظ<EFBFBD><EFBFBD>Ĵ<EFBFBD><EFBFBD>롣
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**3. 简单实现方案**
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使用继承的解决方案如下，这种方案代码无法复用，如果两个鸭子类拥有同样的飞行方式，就有两份重复的代码。
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**4. <20><><EFBFBD><EFBFBD>ԭ<EFBFBD><D4AD>**
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**<EFBFBD><EFBFBD>װ<EFBFBD>仯**<2A><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>仯<EFBFBD><E4BBAF><EFBFBD><EFBFBD>Ѽ<EFBFBD>ӽкͷ<D0BA><CDB7>е<EFBFBD><D0B5><EFBFBD>Ϊ<EFBFBD><CEAA>ʽ<EFBFBD><CABD>
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**4. 设计原则**
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**<EFBFBD><EFBFBD><EFBFBD>Խӿڱ<EFBFBD><EFBFBD>̣<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ֱ<EFBFBD><EFBFBD><EFBFBD>** <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD>࣬<EFBFBD><E0A3AC><EFBFBD><EFBFBD><EFBFBD>Ǿ<EFBFBD><C7BE><EFBFBD><EFBFBD><EFBFBD>ij<EFBFBD><C4B3><EFBFBD><EFBFBD><EFBFBD>ࡣ<EFBFBD><E0A1A3><EFBFBD><EFBFBD><EFBFBD>еķ<D0B5><C4B7><EFBFBD>ʵ<EFBFBD>ֲ<EFBFBD><D6B2>ڸ<EFBFBD><DAB8>࣬<EFBFBD><E0A3AC><EFBFBD><EFBFBD><EFBFBD>ڸ<EFBFBD><DAB8><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ<EFBFBD><E0A1A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD>Զ<EFBFBD>̬<EFBFBD>ı<EFBFBD><C4B1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ָ<EFBFBD><D6B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>͡<EFBFBD>
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**封装变化**在这里变化的是鸭子叫和飞行的行为方式。
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һԭ<EFBFBD><EFBFBD><EFBFBD>кͷ<EFBFBD><EFBFBD>е<EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ֶ<EFBFBD><EFBFBD>ֲ<EFBFBD>ͬ<EFBFBD>Ľкͷ<EFBFBD><EFBFBD>е<EFBFBD><EFBFBD><EFBFBD><EFBFBD>࣬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȥʵ<EFBFBD>־<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľкͷ<EFBFBD><EFBFBD>з<EFBFBD>ʽ<EFBFBD><EFBFBD>
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**针对接口编程，而不是针对实现编程** 变量声明的类型为父类，而不是具体的某个子类。父类中的方法实现不在父类，而是在各个子类。程序在运行时可以动态改变变量所指向的子类类型。
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运用这一原则，将叫和飞行的行为抽象出来，实现多种不同的叫和飞行的子类，让子类去实现具体的叫和飞行方式。
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**<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ü̳<EFBFBD>** <20><><EFBFBD><EFBFBD>Ҳ<EFBFBD><D2B2><EFBFBD><EFBFBD> has-a <20><>ϵ<EFBFBD><CFB5>ͨ<EFBFBD><CDA8><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD><CFA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><CAB1>̬<EFBFBD>ı<EFBFBD>ʵ<EFBFBD>֣<EFBFBD>ֻҪͨ<D2AA><CDA8><EFBFBD>ı丸<C4B1><E4B8B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ָ<EFBFBD><D6B8><EFBFBD>ĸ<EFBFBD><C4B8><EFBFBD><EFBFBD>༴<EFBFBD>ɡ<EFBFBD><C9A1><EFBFBD><EFBFBD>̳оͲ<D0BE><CDB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><D0A9><EFBFBD>̳<EFBFBD><CCB3><EFBFBD>ϵ<EFBFBD>ڴ<EFBFBD><DAB4><EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD>Ѿ<EFBFBD>ȷ<EFBFBD><C8B7><EFBFBD><EFBFBD>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һԭ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Duck <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> FlyBehavior <20><> QuackBehavior <20>࣬performQuack() <20><> performFly() <20><><EFBFBD><EFBFBD>ί<EFBFBD>и<EFBFBD><D0B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȥ<EFBFBD><C8A5><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><CDA8><EFBFBD><EFBFBD><EFBFBD>ַ<EFBFBD>ʽ<EFBFBD><CABD>һ<EFBFBD><D2BB> Duck <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ը<EFBFBD><D4B8><EFBFBD><EFBFBD><EFBFBD>Ҫȥʵ<C8A5><CAB5><EFBFBD><EFBFBD> FlyBehavior <20><> QuackBehavior <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><F3A3ACB2><EFBFBD>Ҳ<EFBFBD><D2B2><EFBFBD>Զ<EFBFBD>̬<EFBFBD>ؽ<EFBFBD><D8BD>иı䡣
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**多用组合，少用继承** 组合也就是 has-a 关系，通过组合，可以在运行时动态改变实现，只要通过改变父类对象具体指向哪个子类即可。而继承就不能做到这些，继承体系在创建类时就已经确定。
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运用这一原则，在 Duck 类中组合 FlyBehavior 和 QuackBehavior 类，performQuack() 和 performFly() 方法委托给这两个类去处理。通过这种方式，一个 Duck 子类可以根据需要去实例化 FlyBehavior 和 QuackBehavior 的子类对象，并且也可以动态地进行改变。
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**5. <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
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**5. 整体设计图**
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**6. ģʽ<C4A3><CABD><EFBFBD><EFBFBD>**
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**<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ** <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>㷨<EFBFBD>壬<EFBFBD>ֱ<EFBFBD><D6B1><EFBFBD>װ<EFBFBD><D7B0><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>֮<EFBFBD><D6AE><EFBFBD><EFBFBD><EFBFBD>Ի<EFBFBD><D4BB><EFBFBD><EFBFBD>滻<EFBFBD><E6BBBB><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD>㷨<EFBFBD>ı仯<C4B1><E4BBAF><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9><EFBFBD>㷨<EFBFBD>Ŀͻ<C4BF><CDBB><EFBFBD>
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**6. 模式定义**
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**7. ʵ<>ִ<EFBFBD><D6B4><EFBFBD>**
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**策略模式** ：定义了算法族，分别封装起来，让它们之间可以互相替换，此模式让算法的变化独立于使用算法的客户。
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**7. 实现代码**
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```java
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public abstract class Duck {
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@ -162,42 +163,42 @@ public class MiniDuckSimulator {
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}
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}
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```
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ִ<EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
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执行结果
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```html
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QuackBehavior.Quack
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FlyBehavior.FlyWithWings
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FlyBehavior.FlyNoWay
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```
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# <EFBFBD><EFBFBD> 2 <EFBFBD><EFBFBD> <20>۲<EFBFBD><DBB2><EFBFBD>ģʽ
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# 第 2 章 观察者模式
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**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
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**1. 模式定义**
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>˶<EFBFBD><EFBFBD><EFBFBD>֮<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD>Զ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı<EFBFBD>״̬ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߶<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ܵ<EFBFBD>֪ͨ<EFBFBD><EFBFBD><EFBFBD>Զ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>¡<EFBFBD><EFBFBD><EFBFBD><EFBFBD>⣨Subject<EFBFBD><EFBFBD><EFBFBD>DZ<EFBFBD><EFBFBD>۲<EFBFBD><EFBFBD>Ķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ߣ<EFBFBD>Observer<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD>۲<EFBFBD><EFBFBD>ߡ<EFBFBD>
|
||||
定义了对象之间的一对多依赖，当一个对象改变状态时，它的所有依赖者都会受到通知并自动更新。主题（Subject）是被观察的对象，而其所有依赖者（Observer）成为观察者。
|
||||
|
||||
|
||||
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>о<EFBFBD><EFBFBD><EFBFBD>ע<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ƴ<EFBFBD><EFBFBD>۲<EFBFBD><EFBFBD>ߣ<EFBFBD><EFBFBD><EFBFBD>֪ͨ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ע<EFBFBD><EFBFBD><EFBFBD>ߵĹ<EFBFBD><EFBFBD>ܣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD>ά<EFBFBD><EFBFBD>һ<EFBFBD>Ź۲<EFBFBD><EFBFBD><EFBFBD><EFBFBD>б<EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ġ<EFBFBD>
|
||||
主题中具有注册和移除观察者，并通知所有注册者的功能，主题是通过维护一张观察者列表来实现这些操作的。
|
||||
|
||||
<EFBFBD>۲<EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ã<EFBFBD><EFBFBD><EFBFBD>Ϊע<EFBFBD>ᡢ<EFBFBD>Ƴ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>У<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD><EFBFBD>ܡ<EFBFBD>
|
||||
观察者拥有一个主题对象的引用，因为注册、移除还有数据都在主题当中，必须通过操作主题才能完成相应功能。
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**3. 问题描述**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݲ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı<EFBFBD>ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ж<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӡ<EFBFBD>
|
||||
天气数据布告板会在天气信息发生改变时更新其内容，布告板有多个，并且在将来会继续增加。
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**
|
||||
**5. 设计原则**
|
||||
|
||||
**Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>֮<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ƶ<EFBFBD>Ŭ<EFBFBD><EFBFBD>** <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>֮<EFBFBD><D6AE><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD><CFA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ȼ<EFBFBD><C8BB><EFBFBD>Խ<EFBFBD><D4BD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Dz<EFBFBD>̫<EFBFBD><CCAB><EFBFBD><EFBFBD><EFBFBD>˴˵<CBB4>ϸ<EFBFBD>ڡ<EFBFBD><DAA1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵ<EFBFBD><CFB5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>֮<EFBFBD>以<EFBFBD><E4BBA5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>̶Ⱥܵͣ<DCB5><CDA3><EFBFBD><EFBFBD><EFBFBD>ϵͳ<CFB5><CDB3><EFBFBD>е<EFBFBD><D0B5>ԣ<EFBFBD><D4A3>ܹ<EFBFBD>Ӧ<EFBFBD>Ա仯<D4B1><E4BBAF>
|
||||
**为交互对象之间的松耦合设计而努力** 当两个对象之间松耦合，它们依然可以交互，但是不太清楚彼此的细节。由于松耦合的两个对象之间互相依赖程度很低，因此系统具有弹性，能够应对变化。
|
||||
|
||||
**6. ʵ<EFBFBD>ִ<EFBFBD><EFBFBD><EFBFBD>**
|
||||
**6. 实现代码**
|
||||
|
||||
```java
|
||||
public interface Subject {
|
||||
@ -295,7 +296,7 @@ public class WeatherStation {
|
||||
}
|
||||
}
|
||||
```
|
||||
ִ<EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
执行结果
|
||||
```html
|
||||
CurrentConditionsDisplay.update:0.0 0.0 0.0
|
||||
StatisticsDisplay.update:0.0 0.0 0.0
|
||||
@ -303,39 +304,39 @@ CurrentConditionsDisplay.update:1.0 1.0 1.0
|
||||
StatisticsDisplay.update:1.0 1.0 1.0
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 3 <EFBFBD><EFBFBD> װ<><D7B0>ģʽ
|
||||
# 第 3 章 装饰模式
|
||||
|
||||
**1. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 问题描述**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>Ʋ<EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ͽ<EFBFBD><EFBFBD>Զ<EFBFBD>̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>µIJ<EFBFBD><EFBFBD>ϣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ţ<EFBFBD>̡<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵļ۸<EFBFBD><EFBFBD><EFBFBD>
|
||||
设计不同种类的饮料，并且每种饮料可以动态添加新的材料，比如可以添加牛奶。计算一种饮料的价格。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**2. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD>̬<EFBFBD>ؽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>θ<EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϡ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>չ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ṩ<EFBFBD>˱ȼ̳и<EFBFBD><EFBFBD>е<EFBFBD><EFBFBD>Ե<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
动态地将责任附加到对象上。在扩展功能上，装饰者提供了比继承更有弹性的替代方案。
|
||||
|
||||
<EFBFBD><EFBFBD>ͼ<EFBFBD><EFBFBD> DarkRoast <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Mocha <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Mocha <20><><EFBFBD><EFBFBD><EFBFBD>ֱ<EFBFBD> Whip <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ƕ<EFBFBD><C7B6>̳<EFBFBD><CCB3><EFBFBD><EFBFBD><EFBFBD>ͬ<EFBFBD><CDAC><EFBFBD>࣬<EFBFBD><E0A3AC><EFBFBD><EFBFBD> cost() <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> cost() <20><><EFBFBD><EFBFBD>ʵ<EFBFBD>ֵ<EFBFBD><D6B5><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڲ<EFBFBD><DAB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> cost() <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ˣ<EFBFBD><CBA3><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA> DarkRoast <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Mocha<68><61><EFBFBD><EFBFBD>ôֻ<C3B4><D6BB>Ҫ<EFBFBD><D2AA> Mocha <EFBFBD><EFBFBD><EFBFBD><EFBFBD> DarkRoast<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ Whip <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Whip <EFBFBD><EFBFBD><EFBFBD><EFBFBD> Mocha<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> cost() <20><><EFBFBD><EFBFBD><EFBFBD>ܰ<EFBFBD><DCB0><EFBFBD><EFBFBD>ֶ<EFBFBD><D6B6><EFBFBD><EFBFBD>ļ۸<DBB8><F1B6BCB0><EFBFBD><EFBFBD><EFBFBD>ȥ<EFBFBD><C8A5>
|
||||
下图中 DarkRoast 对象被 Mocha 包裹，Mocha 对象又被 Whip 包裹，并且他们都继承自相同父类，都有 cost() 方法，但是外层对象的 cost() 方法实现调用了内层对象的 cost() 方法。因此，如果要在 DarkRoast 上添加 Mocha，那么只需要用 Mocha 包裹 DarkRoast，如果还需要 Whip ，就用 Whip 包裹 Mocha，最后调用 cost() 方法能把三种对象的价格都包含进去。
|
||||
|
||||
|
||||
|
||||
|
||||
**3. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**3. 模式类图**
|
||||
|
||||
װ<EFBFBD><EFBFBD><EFBFBD>ߺ;<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>̳<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>о<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ķ<EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ֲ<EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ͷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߾<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>νװ<EFBFBD>Σ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ǰ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڱ<EFBFBD>װ<EFBFBD>εĶ<EFBFBD><EFBFBD><EFBFBD>֮<EFBFBD>⣬<EFBFBD>Ӷ<EFBFBD><EFBFBD><EFBFBD>̬<EFBFBD><EFBFBD>չ<EFBFBD><EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD>ߵĹ<EFBFBD><EFBFBD>ܡ<EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD>ߵķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD><EFBFBD>ģ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĺ<EFBFBD><EFBFBD>ܣ<EFBFBD>Ȼ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ñ<EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD>ߵķ<EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>֣<EFBFBD><EFBFBD>Ӷ<EFBFBD>Ҳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>˱<EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD>ߵĹ<EFBFBD><EFBFBD>ܡ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Կ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>װ<EFBFBD>β<EFBFBD><EFBFBD>ε<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ͳ㣬<EFBFBD><EFBFBD>Ϊֻ<EFBFBD>о<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֱ<EFBFBD><EFBFBD>ʵ<EFBFBD>ֶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫί<EFBFBD>и<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȥ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
装饰者和具体组件都继承自组件类型，其中具体组件的方法实现不需要依赖于其它对象，而装饰者拥有一个组件类型对象，这样它可以装饰其它装饰者或者具体组件。所谓装饰，就是把这个装饰者套在被装饰的对象之外，从而动态扩展被装饰者的功能。装饰者的方法有一部分是自己的，这属于它的功能，然后调用被装饰者的方法实现，从而也保留了被装饰者的功能。可以看到，具体组件应当是装饰层次的最低层，因为只有具体组件有直接实现而不需要委托给其它对象去处理。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 问题解决方案的类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**
|
||||
**5. 设计原则**
|
||||
|
||||
**<EFBFBD><EFBFBD>Ӧ<EFBFBD>ö<EFBFBD><EFBFBD><EFBFBD>չ<EFBFBD><EFBFBD><EFBFBD>ţ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĺرա<EFBFBD>** Ҳ<><D2B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>¹<EFBFBD><C2B9><EFBFBD>ʱ<EFBFBD><CAB1><EFBFBD><EFBFBD>Ҫ<EFBFBD>Ĵ<DEB8><C4B4>롣<EFBFBD>ڱ<EFBFBD><DAB1><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>и<EFBFBD>ԭ<EFBFBD><D4AD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڣ<EFBFBD><DAA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>µIJ<C2B5><C4B2>ϣ<EFBFBD><CFA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫȥ<D2AA><EFBFBD><DEB8><EFBFBD><EFBFBD>ϵĴ<CFB5><C4B4>롣<EFBFBD>۲<EFBFBD><DBB2><EFBFBD>ģʽҲ<CABD><D2B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD><F2A1A3B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><E0B6BC>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><D4AD><EFBFBD><EFBFBD>Ӧ<EFBFBD><D3A6><EFBFBD>Ѹ<EFBFBD>ԭ<EFBFBD><D4AD>Ӧ<EFBFBD><D3A6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>п<EFBFBD><D0BF>ܸı<DCB8><C4B1>ĵط<C4B5><D8B7><EFBFBD>
|
||||
**类应该对扩展开放，对修改关闭。** 也就是添加新功能时不需要修改代码。在本章问题中该原则体现在，在饮料中添加新的材料，而不需要去修改饮料的代码。观察则模式也符合这个原则。不可能所有类都能实现这个原则，应当把该原则应用于设计中最有可能改变的地方。
|
||||
|
||||
**6. Java I/O <EFBFBD>е<EFBFBD>װ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ**
|
||||
**6. Java I/O 中的装饰者模式**
|
||||
|
||||
|
||||
|
||||
|
||||
**7. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**7. 代码实现**
|
||||
|
||||
```java
|
||||
public interface Beverage {
|
||||
@ -400,32 +401,32 @@ public class StartbuzzCoffee {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
输出
|
||||
|
||||
```html
|
||||
3.0
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 4 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 4 章 工厂模式
|
||||
|
||||
## 4.1 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
## 4.1 简单工厂
|
||||
|
||||
**1. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 问题描述**
|
||||
|
||||
<EFBFBD>в<EFBFBD>ͬ<EFBFBD><EFBFBD> Pizza<7A><61><EFBFBD><EFBFBD><EFBFBD>ݲ<EFBFBD>ͬ<EFBFBD><CDAC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ò<EFBFBD>ͬ<EFBFBD><CDAC><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> Pizza <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
有不同的 Pizza，根据不同的情况用不同的子类实例化一个 Pizza 对象。
|
||||
|
||||
**2. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**2. 定义**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD>ֱ<EFBFBD><EFBFBD><EFBFBD>ϰ<EFBFBD>ߡ<EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ķ<EFBFBD><EFBFBD><EFBFBD>ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD>ݾ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD>ĸ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>£<EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>IJ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ŵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>У<EFBFBD><EFBFBD>ù<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ĸ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ѿͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>;<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ֽ<EFBFBD><EFBFBD><EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ֪<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ĸ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ<EFBFBD><EFBFBD>Ϊ<EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ж<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD>ü<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ô<EFBFBD><EFBFBD><EFBFBD>еĿͻ<EFBFBD><EFBFBD>Ҫ֪<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϸ<EFBFBD>ڣ<EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı䣬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>࣬<EFBFBD><EFBFBD>ô<EFBFBD><EFBFBD><EFBFBD>еĿͻ<EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı䡣
|
||||
简单工厂不是设计模式，更像是一种编程习惯。在实例化一个超类的对象时，可以用它的所有子类来进行实例化，要根据具体需求来决定使用哪个子类。在这种情况下，把实例化的操作放到工厂来中，让工厂类来决定应该用哪个子类来实例化。这样做把客户对象和具体子类的实现解耦，客户对象不再需要知道有哪些子类以及实例化哪个子类。因为客户类往往有多个，如果不使用简单工厂，那么所有的客户类都要知道所有子类的细节，一旦子类发生改变，例如增加子类，那么所有的客户类都要发生改变。
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**3. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**4. 代码实现**
|
||||
|
||||
```java
|
||||
public interface Pizza {
|
||||
@ -471,35 +472,35 @@ public class PizzaStore {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
|
||||
```java
|
||||
CheesePizza
|
||||
```
|
||||
|
||||
## 4.2 <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
## 4.2 工厂方法模式
|
||||
|
||||
**1. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 问题描述**
|
||||
|
||||
ÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Pizza <20><><EFBFBD><EFBFBD>Ȼ<EFBFBD><C8BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͬ<EFBFBD><CDAC><EFBFBD><EFBFBD><EFBFBD>Ƕ<EFBFBD><C7B6><EFBFBD><EFBFBD>Լ<EFBFBD><D4BC>ķ<EFBFBD>ζ<EFBFBD><CEB6><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>֡<EFBFBD><D6A1><EFBFBD><EFBFBD>磬һ<E7A3AC><D2BB><EFBFBD>ͻ<EFBFBD><CDBB><EFBFBD><EFBFBD><EFBFBD>ŦԼ<C5A6><D4BC> cheese <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Pizza <EFBFBD><EFBFBD><EFBFBD><EFBFBD>֥<EFBFBD>Ӹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Pizza <20>Dz<EFBFBD>ͬ<EFBFBD>ġ<EFBFBD>
|
||||
每个地区的 Pizza 店虽然种类相同，但是都有自己的风味，需要单独区分。例如，一个客户点了纽约的 cheese 种类的 Pizza 和在芝加哥点的相同种类的 Pizza 是不同的。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**2. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľӿڣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ƴٵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ
|
||||
定义了一个创建对象的接口，但由子类决定要实例化的类是哪一个。工厂方法让类把实例化推迟到子类。
|
||||
|
||||
**3. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**3. 模式类图**
|
||||
|
||||
<EFBFBD>ڼ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>У<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>࣬<EFBFBD><EFBFBD><EFBFBD>ڹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>У<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ<EFBFBD>У<EFBFBD>Creator <EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD> anOperation() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD>õ<EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ʒ<EFBFBD>࣬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ʒ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
在简单工厂中，创建对象的是另一个类，而在工厂方法中，是由子类来创建对象。下图中，Creator 有一个 anOperation() 方法，这个方法需要用到一组产品类，这组产品类由每个子类来创建。
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ഴ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ļ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ÿһ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ʒ<EFBFBD>࣬<EFBFBD><EFBFBD><EFBFBD>ǰѼ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>д<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ŵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ŀ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Dz<EFBFBD>Ʒ<EFBFBD>࣬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ô<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
可以为每个子类创建单独的简单工厂来创建每一个产品类，但是把简单工厂中创建对象的代码放到子类中来可以减少类的数目，因为子类不算是产品类，因此完全可以这么做。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**5. 代码实现**
|
||||
|
||||
```java
|
||||
public interface Pizza {
|
||||
@ -588,36 +589,36 @@ public class PizzaTestDrive {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
|
||||
```html
|
||||
NYStyleCheesePizza is making..
|
||||
ChicagoStyleCheesePizza is making..
|
||||
```
|
||||
|
||||
## 4.3 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
## 4.3 抽象工厂模式
|
||||
|
||||
**1. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**
|
||||
**1. 设计原则**
|
||||
|
||||
**<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**<2A><>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ<EFBFBD><E0A1A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Խӿڱ<D3BF><DAB1>̣<EFBFBD><CCA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ֱ<EFBFBD><D6B1>̣<EFBFBD><CCA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><D4AD>˵<EFBFBD><CBB5><EFBFBD>ˣ<EFBFBD><CBA3><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ø߲<C3B8><DFB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ײ<EFBFBD><D7B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ң<EFBFBD><D2A3><EFBFBD><EFBFBD>ܸ߲<DCB8><DFB2><EFBFBD><EFBFBD>ײ<EFBFBD><D7B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߶<EFBFBD>Ӧ<EFBFBD><D3A6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڳ<EFBFBD><DAB3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>磬<EFBFBD><E7A3AC>ͼ<EFBFBD><CDBC> PizzaStore <20><><EFBFBD>ڸ߲<DAB8><DFB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Pizza <20>ij<EFBFBD><C4B3><EFBFBD><EFBFBD>࣬<EFBFBD><E0A3AC><EFBFBD><EFBFBD><EFBFBD>Ϳ<EFBFBD><CDBF>Բ<EFBFBD><D4B2>ù<EFBFBD><C3B9><EFBFBD> Pizza <20>ľ<EFBFBD><C4BE><EFBFBD>ʵ<EFBFBD><CAB5>ϸ<EFBFBD>ڡ<EFBFBD>
|
||||
**依赖倒置原则**：要依赖抽象，不要依赖具体类。听起来像是针对接口编程，不针对实现编程，但是这个原则说明了：不能让高层组件依赖底层组件，而且，不管高层或底层组件，两者都应该依赖于抽象。例如，下图中 PizzaStore 属于高层组件，它依赖的是 Pizza 的抽象类，这样就可以不用关心 Pizza 的具体实现细节。
|
||||
|
||||
|
||||
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**2. 模式定义**
|
||||
|
||||
<EFBFBD>ṩһ<EFBFBD><EFBFBD><EFBFBD>ӿڣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڴ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ػ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ļ<EFBFBD><EFBFBD>壬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD>ȷָ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ
|
||||
提供一个接口，用于创建相关或依赖对象的家族，而不需要明确指定具体类。
|
||||
|
||||
**3. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**3. 模式类图**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ƕ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>壬Ҳ<EFBFBD><EFBFBD><EFBFBD>Ǻܶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>صģ<EFBFBD>Ҳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>˵<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽֻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڴ<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͳ<EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD>кܴ<EFBFBD><EFBFBD><EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ң<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽҲ<EFBFBD>õ<EFBFBD><EFBFBD>˹<EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ<EFBFBD><EFBFBD>AbstractFactory <EFBFBD>е<EFBFBD> CreateProductA <EFBFBD><EFBFBD> CreateProductB <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>֣<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڴ<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϲ<EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD>Ķ<EFBFBD><EFBFBD>塣<EFBFBD><EFBFBD><EFBFBD>ڴ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ļ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Client <EFBFBD><EFBFBD><EFBFBD>֣<EFBFBD>Client Ҫͨ<EFBFBD><EFBFBD> AbstractFactory ͬʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>кܴ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԣ<EFBFBD>Client <20><>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Э<EFBFBD><D0AD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӹ߲<D3B8><DFB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD><CFA3><EFBFBD> Cilent <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> AbstractFactory <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽʹ<EFBFBD><EFBFBD><EFBFBD>˼̳С<EFBFBD>
|
||||
抽象工厂模式创建的是对象家族，也就是很多对象而不是一个对象，并且这些对象是相关的，也就是说必须一起创建出来。而工厂模式只是用于创建一个对象，这和抽象工厂模式有很大不同。并且，抽象工厂模式也用到了工厂模式来创建单一对象，在类图左部，AbstractFactory 中的 CreateProductA 和 CreateProductB 方法都是让子类来实现，这两个方法单独来看就是在创建一个对象，这符合工厂模式的定义。至于创建对象的家族这一概念是在 Client 体现，Client 要通过 AbstractFactory 同时调用两个方法来创建出两个对象，在这里这两个对象就有很大的相关性，Client 需要这两个对象的协作才能完成任务。从高层次来看，抽象工厂使用了组合，即 Cilent 组合了 AbstractFactory ，而工厂模式使用了继承。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**5. 代码实现**
|
||||
|
||||
```java
|
||||
public interface Dough {
|
||||
@ -719,28 +720,28 @@ public class NYPizzaStoreTestDrive {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
|
||||
```html
|
||||
ThickCrustDough
|
||||
MarinaraSauce
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 5 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 5 章 单件模式
|
||||
|
||||
**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 模式定义**
|
||||
|
||||
ȷ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֻ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ṩ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>ȫ<EFBFBD>ַ<EFBFBD><EFBFBD>ʵ㡣
|
||||
确保一个类只有一个实例，并提供了一个全局访问点。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD> Java ʵ<><CAB5><EFBFBD><EFBFBD>һ<EFBFBD><D2BB>˽<EFBFBD>й<EFBFBD><D0B9><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB>˽<EFBFBD>о<EFBFBD>̬<EFBFBD><CCAC><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD><EFBFBD>о<EFBFBD>̬<EFBFBD><CCAC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ú<EFBFBD><C3BA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>˽<EFBFBD>б<EFBFBD><D0B1><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><CDA8><EFBFBD>ú<EFBFBD><C3BA><EFBFBD><EFBFBD><EFBFBD>ȡ<EFBFBD>Ķ<EFBFBD><C4B6><EFBFBD><EFBFBD><EFBFBD>ָ<EFBFBD><D6B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ψһ<CEA8><D2BB>˽<EFBFBD>о<EFBFBD>̬<EFBFBD><CCAC><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
单件模式的 Java 实现用一个私有构造器、一个私有静态变量以及一个公有静态函数，该函数返回私有变量，使得所有通过该函数获取的对象都指向这个唯一的私有静态变量。
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**3. 经典实现**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD>У<EFBFBD>˽<EFBFBD>о<EFBFBD>̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӳٻ<EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ĺô<EFBFBD><EFBFBD>ǣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>û<EFBFBD><EFBFBD><EFBFBD>õ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>࣬<EFBFBD><EFBFBD>ô<EFBFBD>Ͳ<EFBFBD><EFBFBD>ᴴ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>˽<EFBFBD>о<EFBFBD>̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӷ<EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD><EFBFBD>Դ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD>ڶ<EFBFBD><EFBFBD>̻߳<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Dz<EFBFBD><EFBFBD><EFBFBD>ȫ<EFBFBD>ģ<EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߳<EFBFBD><EFBFBD>ܹ<EFBFBD>ͬʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD> if(uniqueInstance == null) <EFBFBD>ڵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>飬<EFBFBD><EFBFBD>ô<EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD> uniqueInstance ˽<EFBFBD>о<EFBFBD>̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
以下实现中，私有静态变量被延迟化实例化，这样做的好处是，如果没有用到该类，那么就不会创建该私有静态变量，从而节约资源。这个实现在多线程环境下是不安全的，因为多个线程能够同时进入 if(uniqueInstance == null) 内的语句块，那么就会多次实例化 uniqueInstance 私有静态变量。
|
||||
|
||||
```java
|
||||
public class Singleton {
|
||||
@ -759,9 +760,9 @@ public class Singleton {
|
||||
}
|
||||
```
|
||||
|
||||
**4. <EFBFBD>̲߳<EFBFBD><EFBFBD><EFBFBD>ȫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ**
|
||||
**4. 线程不安全问题的解决方案一**
|
||||
|
||||
ֻ<EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD> getUniqueInstance() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ø÷<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>ֻ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>̷߳<EFBFBD><EFBFBD>ʣ<EFBFBD><EFBFBD>Ӷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>˶<EFBFBD> uniqueInstance <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ж<EFBFBD><D0B6><EFBFBD>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>⡣<EFBFBD><E2A1A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB>ֻ<EFBFBD><D6BB>һ<EFBFBD><D2BB><EFBFBD>߳̽<DFB3><CCBD>룬<EFBFBD><EBA3AC><EFBFBD><EFBFBD><EFBFBD>ϻ<EFBFBD><CFBB><EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD><EFBFBD>˷ѡ<CBB7>
|
||||
只需要对 getUniqueInstance() 方法加锁，就能让该方法一次只能一个线程访问，从而避免了对 uniqueInstance 变量进行多次实例化的问题。但是这样有一个问题是一次只能一个线程进入，性能上会有一定的浪费。
|
||||
|
||||
```java
|
||||
public static synchronized Singleton getUniqueInstance() {
|
||||
@ -772,17 +773,17 @@ public class Singleton {
|
||||
}
|
||||
```
|
||||
|
||||
**5. <EFBFBD>̲߳<EFBFBD><EFBFBD><EFBFBD>ȫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**5. 线程不安全问题的解决方案二**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӳ<EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֱ<EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
不用延迟实例化，采用直接实例化。
|
||||
|
||||
```java
|
||||
private static Singleton uniqueInstance = new Singleton();
|
||||
```
|
||||
|
||||
**6. <EFBFBD>̲߳<EFBFBD><EFBFBD><EFBFBD>ȫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**6. 线程不安全问题的解决方案三**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>ǵ<EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֱ<EFBFBD>Ӷ<EFBFBD> getUniqueInstance() <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>м<EFBFBD><D0BC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD>ֻ<EFBFBD><D6BB>Ҫ<EFBFBD><D2AA> uniqueInstance = new Singleton(); <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ɡ<EFBFBD>ʹ<EFBFBD><CAB9><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ж<EFBFBD> uniqueInstance <20>Ƿ<EFBFBD><C7B7>Ѿ<EFBFBD>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>û<EFBFBD><C3BB>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
考虑第一个解决方案，它是直接对 getUniqueInstance() 方法进行加锁，而实际上只需要对 uniqueInstance = new Singleton(); 这条语句加锁即可。使用两个条件语句来判断 uniqueInstance 是否已经实例化，如果没有实例化才需要加锁。
|
||||
|
||||
```java
|
||||
public class Singleton {
|
||||
@ -805,31 +806,31 @@ public class Singleton {
|
||||
}
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 6 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 6 章 命令模式
|
||||
|
||||
**1. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 问题描述**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>ң<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>кܶఴť<EFBFBD><EFBFBD>ÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ť<EFBFBD><EFBFBD><EFBFBD>Է<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>ҵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>зdz<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ļҵ磬<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӽҵ硣
|
||||
设计一个遥控器，它有很多按钮，每个按钮可以发起一个命令，让一个家电完成相应操作。有非常多的家电，并且也会增加家电。
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**2. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>װ<EFBFBD>ɶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ա<EFBFBD>ʹ<EFBFBD>ò<EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
将命令封装成对象，以便使用不同的命令来参数化其它对象。
|
||||
|
||||
**3. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**3. 模式类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
Invoker <EFBFBD><EFBFBD>ң<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ҵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> execute() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Receiver <EFBFBD>ǵ<EFBFBD><EFBFBD>ƣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ִ<EFBFBD><EFBFBD><EFBFBD>ߡ<EFBFBD>ConcreteCommand <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> Receiver <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ִ<EFBFBD><D6B4>ί<EFBFBD>и<EFBFBD> Receiver <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҳ<EFBFBD><D2B2><EFBFBD><EFBFBD> LightOnCommand <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> excute <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ί<EFBFBD>и<EFBFBD> Light <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Light <20><><EFBFBD><EFBFBD>ͨ<EFBFBD><CDA8><EFBFBD><EFBFBD><EFBFBD><EFBFBD> on() <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ɲ<EFBFBD><C9B2><EFBFBD><EFBFBD><EFBFBD>Invoker <EFBFBD><EFBFBD><EFBFBD><EFBFBD> Client <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Invoker <20><><EFBFBD><EFBFBD><EFBFBD>ɵģ<C9B5><C4A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Client <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><D0A9><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
Invoker 是遥控器，它可以设置命令，并且调用命令对象的 execute() 方法。Receiver 是电灯，是命令真正的执行者。ConcreteCommand 类组合了一个 Receiver 对象，命令的执行委托给 Receiver 对象来处理，也就是 LightOnCommand 命令的 excute 方法委托给 Light 对象来处理，Light 对象通过调用 on() 方法来完成操作。Invoker 不是 Client 对象，是因为命令的创建不是在 Invoker 中完成的，因此需要额外的 Client 对象来处理这些操作。
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**5. 代码实现**
|
||||
|
||||
```java
|
||||
public interface Command {
|
||||
@ -864,7 +865,7 @@ public class LightOnCommand implements Command{
|
||||
```
|
||||
```java
|
||||
/**
|
||||
* ң<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
* 遥控器类
|
||||
*/
|
||||
public class SimpleRemoteControl {
|
||||
Command slot;
|
||||
@ -895,39 +896,39 @@ public class RemoteLoader {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
输出
|
||||
|
||||
```html
|
||||
Light is on!
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 7 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<C4A3><CABD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 7 章 适配器模式与外观模式
|
||||
|
||||
## 7.1 <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
## 7.1 适配器模式
|
||||
|
||||
**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľӿڣ<EFBFBD>ת<EFBFBD><EFBFBD>Ϊ<EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>ӿڡ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ժ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>䡣
|
||||
将一个类的接口，转换为客户期望的另一个接口。适配器让原本不兼容的类可以合作无间。
|
||||
|
||||
|
||||
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD>ʵ<EFBFBD>֣<EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>Ƕ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࣨAdapter<EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Adaptee<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD>Ĵ<EFBFBD><EFBFBD><EFBFBD>ί<EFBFBD>и<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ<EFBFBD>õ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ؼ̳У<EFBFBD>Adapter <EFBFBD><EFBFBD><EFBFBD>Կ<EFBFBD><EFBFBD><EFBFBD> Target <EFBFBD><EFBFBD> Adaptee <EFBFBD><EFBFBD><EFBFBD>ͣ<EFBFBD><EFBFBD>Ȱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Adaptee <20><><EFBFBD><EFBFBD>Ȼ<EFBFBD><C8BB>ʵ<EFBFBD><CAB5><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> Adapter <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ٰ<EFBFBD><D9B0><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Target <20><><EFBFBD>͵ģ<CDB5><C4A3><EFBFBD><EFBFBD><EFBFBD> Client <20>Ϳ<EFBFBD><CDBF><EFBFBD><D4B0><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Target <20>Ķ<EFBFBD><C4B6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
有两种适配器模式的实现，一种是对象方式，一种是类方式。对象方式是通过组合的方法，让适配器类（Adapter）拥有一个待适配的对象（Adaptee），从而把相应的处理委托给待适配的对象。类方式用到多重继承，Adapter 可以看成 Target 和 Adaptee 类型，先把它当成 Adaptee 类型然后实例化一个 Adapter 对象，再把它当成 Target 类型的，这样 Client 就可以把这个对象当成 Target 的对象来处理。
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**3. 问题描述**
|
||||
|
||||
<EFBFBD><EFBFBD>Ѽ<EFBFBD>ӣ<EFBFBD>Duck<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Turkey<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Duck <EFBFBD><EFBFBD> quack() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Turkey ֻ<EFBFBD><EFBFBD> gobble() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD> Turkey Ҳ<EFBFBD><EFBFBD> Duck <EFBFBD><EFBFBD> quack() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
让鸭子（Duck）适配火鸡（Turkey），Duck 有 quack() 方法，而 Turkey 只有 gobble() 方法。也就是要让 Turkey 也有 Duck 的 quack() 方法。
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**5. 代码实现**
|
||||
|
||||
```java
|
||||
public interface Duck {
|
||||
@ -984,69 +985,69 @@ public class DuckTestDrive {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
```html
|
||||
gobble!
|
||||
fly!
|
||||
```
|
||||
|
||||
## 7.2 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
## 7.2 外观模式
|
||||
|
||||
**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 模式定义**
|
||||
|
||||
<EFBFBD>ṩ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>ͳһ<EFBFBD>Ľӿڣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵͳ<EFBFBD>е<EFBFBD>һȺ<EFBFBD>ӿڡ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>۶<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>߲<EFBFBD><EFBFBD>ӿڣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵͳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD>á<EFBFBD>
|
||||
提供了一个统一的接口，用来访问子系统中的一群接口。外观定义了一个高层接口，让子系统更容易使用。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**3. 问题描述**
|
||||
|
||||
<EFBFBD><EFBFBD>ͥӰԺ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD>йۿ<EFBFBD><EFBFBD><EFBFBD>Ӱʱ<EFBFBD><EFBFBD>Ҫ<EFBFBD>Ժܶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>в<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD>ü<EFBFBD>ͥӰԺ<EFBFBD><EFBFBD>ֻ<EFBFBD>ṩһ<EFBFBD><EFBFBD><EFBFBD>Ľӿڣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ṩһ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӱ<EFBFBD>Ľӿڶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>þ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
家庭影院中有众多电器，当要进行观看电影时需要对很多电器进行操作。要求简化这些操作，使得家庭影院类只提供一个简化的接口，例如提供一个看电影的接口而不用具体操作众多电器。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**
|
||||
**5. 设计原则**
|
||||
|
||||
**<EFBFBD><EFBFBD><EFBFBD><EFBFBD>֪ʶԭ<EFBFBD><EFBFBD>**<2A><>ֻ<EFBFBD><D6BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD≯<EFBFBD><CCB8><EFBFBD><EFBFBD>Ҳ<EFBFBD><D2B2><EFBFBD><EFBFBD>Ӧ<EFBFBD><D3A6>ʹ<EFBFBD>ÿͻ<C3BF><CDBB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><EFBFBD>Ķ<EFBFBD><C4B6><EFBFBD>Ӧ<EFBFBD><D3A6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>١<EFBFBD>
|
||||
**最少知识原则**：只和你的密友谈话。也就是应当使得客户对象所需要交互的对象应当尽可能少。
|
||||
|
||||
# <EFBFBD><EFBFBD> 8 <EFBFBD><EFBFBD> ģ<>巽<EFBFBD><E5B7BD>ģʽ
|
||||
# 第 8 章 模板方法模式
|
||||
|
||||
**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ж<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>㷨<EFBFBD>ĹǼܣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һЩ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӳٵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>С<EFBFBD>
|
||||
在一个方法中定义一个算法的骨架，而将一些步骤延迟到子类中。
|
||||
|
||||
ģ<EFBFBD>巽<EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڲ<EFBFBD><EFBFBD>ı<EFBFBD><EFBFBD>㷨<EFBFBD>ṹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>£<EFBFBD><EFBFBD><EFBFBD><EFBFBD>¶<EFBFBD><EFBFBD><EFBFBD><EFBFBD>㷨<EFBFBD>е<EFBFBD>ijЩ<EFBFBD><EFBFBD><EFBFBD>衣
|
||||
模板方法使得子类可以在不改变算法结构的情况下，重新定义算法中的某些步骤。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
ģ<EFBFBD>巽<EFBFBD><EFBFBD> templateMethod() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>㷨<EFBFBD>ĹǼܣ<EFBFBD>ȷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD> primitiveOperation1() <EFBFBD><EFBFBD> primitiveOperation2() <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ִ<EFBFBD>е<EFBFBD>˳<EFBFBD><EFBFBD> primitiveOperation1() <EFBFBD><EFBFBD> primitiveOperation2() <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȥ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>֡<EFBFBD>
|
||||
模板方法 templateMethod() 定义了算法的骨架，确定了 primitiveOperation1() 和 primitiveOperation2() 方法执行的顺序，而 primitiveOperation1() 和 primitiveOperation2() 让子类去具体实现。
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**3. 问题描述**
|
||||
|
||||
<EFBFBD>忧<EFBFBD>Ⱥͳ<EFBFBD><EFBFBD>趼<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ƶ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>̣<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ijЩ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>е㲻һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
冲咖啡和冲茶都有类似的流程，但是某些步骤会有点不一样。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ**
|
||||
**4. 解决方案类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**5. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**
|
||||
**5. 设计原则**
|
||||
|
||||
**<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**<2A><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ã<EFBFBD><C3A3><EFBFBD><EFBFBD>绰<EFBFBD><E7BBB0><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ǣ<EFBFBD><C7A3><EFBFBD><EFBFBD>ǻ<EFBFBD><C7BB><EFBFBD><EFBFBD>ã<EFBFBD><C3A3><EFBFBD><EFBFBD>绰<EFBFBD><E7BBB0><EFBFBD><EFBFBD><EFBFBD>㡣<EFBFBD><E3A1A3>һԭ<D2BB><D4AD><EFBFBD><EFBFBD><EFBFBD>Է<EFBFBD>ֹ<EFBFBD><D6B9><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ܣ<EFBFBD><DCA3><EFBFBD><EFBFBD><EFBFBD>ֹ<EFBFBD>߲<EFBFBD><DFB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ײ<EFBFBD><D7B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ײ<EFBFBD><D7B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߲<EFBFBD><DFB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><D4AD><EFBFBD><EFBFBD>ģ<EFBFBD>巽<EFBFBD><E5B7BD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA>ֻ<EFBFBD>и<EFBFBD><D0B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>࣬<EFBFBD><E0A3AC><EFBFBD><EFBFBD><E0B2BB><EFBFBD><EFBFBD><EFBFBD>ø<EFBFBD><C3B8>ࡣ
|
||||
**好莱坞原则**：别调用（打电话给）我们，我们会调用（打电话给）你。这一原则可以防止依赖腐败，即防止高层组件依赖底层组件，底层组件又依赖高层组件。该原则在模板方法的体现为，只有父类会调用子类，子类不会调用父类。
|
||||
|
||||
**6. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**6. 钩子**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>ӣ<EFBFBD>hock<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ijЩ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڲ<EFBFBD>ͬʵ<EFBFBD><EFBFBD><EFBFBD>п<EFBFBD><EFBFBD>п<EFBFBD><EFBFBD>ޣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ȶ<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>ʲô<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD>ģ<EFBFBD>巽<EFBFBD><EFBFBD> templteMethod() <20>У<EFBFBD><D0A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ<EFBFBD><D2AA><EFBFBD><EFBFBD><CDB8><EFBFBD>Ĭ<EFBFBD><C4AC>ʵ<EFBFBD>ֲ<EFBFBD><D6B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD><D4BC><EFBFBD>ʵ<EFBFBD>֡<EFBFBD>
|
||||
钩子（hock）：某些步骤在不同实现中可有可无，可以先定义一个什么都不做的方法，把它加到模板方法 templteMethod() 中，如果子类需要它就覆盖默认实现并加上自己的实现。
|
||||
|
||||
**7. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**7. 代码实现**
|
||||
|
||||
```java
|
||||
public abstract class CaffeineBeverage {
|
||||
@ -1109,7 +1110,7 @@ public class CaffeineBeverageTestDrive {
|
||||
}
|
||||
```
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
|
||||
```html
|
||||
boilWater
|
||||
@ -1123,21 +1124,21 @@ pourInCup
|
||||
Tea.addCondiments
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 9 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 9 章 迭代器和组合模式
|
||||
|
||||
## 9.1 <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
## 9.1 迭代器模式
|
||||
|
||||
**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 模式定义**
|
||||
|
||||
<EFBFBD>ṩһ<EFBFBD><EFBFBD>˳<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>ۺ϶<EFBFBD><EFBFBD><EFBFBD><EFBFBD>еĸ<EFBFBD><EFBFBD><EFBFBD>Ԫ<EFBFBD>صķ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֲ<EFBFBD><EFBFBD><EFBFBD>¶<EFBFBD><EFBFBD><EFBFBD>ڲ<EFBFBD><EFBFBD>ı<EFBFBD>ʾ<EFBFBD><EFBFBD>
|
||||
提供一种顺序访问一个聚合对象中的各个元素的方法，而又不暴露其内部的表示。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
<EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD>ۺ϶<EFBFBD><EFBFBD><EFBFBD><EFBFBD>͵<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ǿۺ϶<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ɵġ<EFBFBD>ֻ<EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ƶ<EFBFBD><EFBFBD>IJ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>þۺ϶<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ܹ<EFBFBD>˳<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
客户类拥有一个聚合对象和迭代器对象，迭代器对象是聚合对象生成的。只需要迭代器定义好移动的操作，就可以让聚合对象能够顺序遍历。
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**3. 代码实现**
|
||||
|
||||
```java
|
||||
public class Aggregate {
|
||||
@ -1195,7 +1196,7 @@ public class Client {
|
||||
}
|
||||
}
|
||||
```
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
```html
|
||||
0
|
||||
1
|
||||
@ -1209,13 +1210,13 @@ public class Client {
|
||||
9
|
||||
```
|
||||
|
||||
## 9.2 Java <EFBFBD><EFBFBD><EFBFBD>õĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
## 9.2 Java 内置的迭代器
|
||||
|
||||
**1. ʵ<EFBFBD>ֽӿ<EFBFBD>**
|
||||
**1. 实现接口**
|
||||
|
||||
Java <EFBFBD><EFBFBD><EFBFBD>Ѿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> Iterator <EFBFBD>ӿڣ<EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD> Java ʵ<><CAB5>ʱ<EFBFBD><CAB1><EFBFBD><EFBFBD>Ҫ<EFBFBD>þۺ϶<DBBA><CFB6><EFBFBD>ʵ<EFBFBD><CAB5> Iterable <20>ӿڣ<D3BF><DAA3>ýӿ<C3BD><D3BF><EFBFBD>һ<EFBFBD><D2BB> iterator() <20><><EFBFBD><EFBFBD><EFBFBD>᷵<EFBFBD><E1B7B5>һ<EFBFBD><D2BB> Iterator <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9> Java <20><><EFBFBD>õĵ<C3B5><C4B5><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>֣<EFBFBD><D6A3>ͻ<EFBFBD><CDBB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><CAB9> foreach ѭ<><D1AD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ۺ϶<DBBA><CFB6><EFBFBD><EFBFBD>е<EFBFBD>ÿ<EFBFBD><C3BF>Ԫ<EFBFBD>ء<EFBFBD>
|
||||
Java 中已经有了 Iterator 接口，在使用 Java 实现时，需要让聚合对象实现 Iterable 接口，该接口有一个 iterator() 方法会返回一个 Iterator 对象。使用 Java 内置的迭代器实现，客户对象可以使用 foreach 循环来遍历聚合对象中的每个元素。
|
||||
|
||||
**2. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**2. 代码实现**
|
||||
|
||||
```java
|
||||
import java.util.Iterator;
|
||||
@ -1271,25 +1272,25 @@ public class Client {
|
||||
}
|
||||
```
|
||||
|
||||
## 9.3 <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ
|
||||
## 9.3 组合模式
|
||||
|
||||
**1. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD>**
|
||||
**1. 设计原则**
|
||||
|
||||
һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD>ֻ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı<EFBFBD><EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
一个类应该只有一个引起改变的原因。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**2. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϳ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>νṹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>֡<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> / <20><><EFBFBD>֡<EFBFBD><D6A1><EFBFBD><EFBFBD>νṹ<CEBD><E1B9B9>
|
||||
允许将对象组合成树形结构来表现“整体 / 部分”层次结构。
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ÿͻ<EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD>µķ<EFBFBD>ʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϡ<EFBFBD>
|
||||
组合能让客户以一致的方式处理个别对象以及对象组合。
|
||||
|
||||
**3. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**3. 模式类图**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϣ<EFBFBD>Composite<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Component<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>϶<EFBFBD><EFBFBD><EFBFBD>λ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>νṹ<EFBFBD><EFBFBD><EFBFBD>м䣬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Լ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>͡<EFBFBD>
|
||||
由于组合（Composite）类拥有一个组件（Component）对象，因此组合对象位于树形结构的中间，它还可以继续操作这个组件对象，并忽略组件对象的具体类型。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**4. 代码实现**
|
||||
|
||||
```java
|
||||
public abstract class Component {
|
||||
@ -1316,7 +1317,7 @@ public class Leaf extends Component {
|
||||
|
||||
@Override
|
||||
public void addChild(Component component) {
|
||||
throw new UnsupportedOperationException(); // <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ի<EFBFBD>ȡ<EFBFBD><EFBFBD>һְ<EFBFBD><EFBFBD>ԭ<EFBFBD><EFBFBD> , <20><><EFBFBD><EFBFBD><EFBFBD>Ͳ<EFBFBD><CDB2>ÿ<EFBFBD><C3BF><EFBFBD><EFBFBD><EFBFBD>Ҷ<EFBFBD>ӽڵ㻹<DAB5><E3BBB9><EFBFBD><EFBFBD><EFBFBD>Ͻڵ<CFBD>
|
||||
throw new UnsupportedOperationException(); // 牺牲透明性换取单一职责原则 , 这样就不用考虑是叶子节点还是组合节点
|
||||
}
|
||||
|
||||
@Override
|
||||
@ -1378,7 +1379,7 @@ public class Client {
|
||||
}
|
||||
}
|
||||
```
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
|
||||
```html
|
||||
Composite:root
|
||||
@ -1390,56 +1391,56 @@ Composite:root
|
||||
--left:3
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 10 <EFBFBD><EFBFBD> ״̬ģʽ
|
||||
# 第 10 章 状态模式
|
||||
|
||||
**1. ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**1. 模式定义**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڲ<EFBFBD>״̬<EFBFBD>ı<EFBFBD>ʱ<EFBFBD>ı<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ࡣ
|
||||
允许对象在内部状态改变时改变它的行为，对象看起来好像修改了它的类。
|
||||
|
||||
״̬ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͼ<EFBFBD>Ͳ<EFBFBD><EFBFBD><EFBFBD>ģʽһ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ܹ<EFBFBD><EFBFBD><EFBFBD>̬<EFBFBD>ı<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>״̬ģʽ<EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>״̬ת<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı<EFBFBD><EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵ<EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵIJ<EFBFBD><EFBFBD>Զ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>磬״̬ģʽ<EFBFBD>£<EFBFBD><EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ί<EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ô״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>п<EFBFBD><EFBFBD>ܷ<EFBFBD><EFBFBD><EFBFBD>״̬ת<EFBFBD>ƣ<EFBFBD>ʹ<EFBFBD>ÿͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ӵ<EFBFBD>е<EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı䡣״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>˿ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>״̬ת<EFBFBD><EFBFBD><EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͨ<EFBFBD><EFBFBD><EFBFBD>ı<EFBFBD><EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ϵ<EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD>ֵġ<EFBFBD>
|
||||
状态模式的类图和策略模式一样，并且都是能够动态改变对象的行为。但是状态模式是通过状态对象的状态转移来改变客户对象组合的状态对象，而策略模式是通过客户对象本身的决策来改变组合的策略对象。例如，状态模式下，客户对象委托状态对象进行一个处理操作，那么状态对象有可能发生状态转移，使得客户对象拥有的状态对象发生改变。状态对象组合了客户对象，状态转移是状态对象通过改变客户对象所组合的状态对象实现的。
|
||||
|
||||
**2. ģʽ<EFBFBD><EFBFBD>ͼ**
|
||||
**2. 模式类图**
|
||||
|
||||
|
||||
|
||||
|
||||
**3. <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**3. 问题描述**
|
||||
|
||||
<EFBFBD>ǹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ۻ<EFBFBD><EFBFBD>ж<EFBFBD><EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD>ÿ<EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ۻ<EFBFBD><EFBFBD>в<EFBFBD>ͬ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD>Է<EFBFBD><EFBFBD><EFBFBD>ת<EFBFBD>ƣ<EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ۻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ΪҲ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ı䡣
|
||||
糖果销售机有多种状态，每种状态下销售机有不同的行为，状态可以发生转移，使得销售机的行为也发生改变。
|
||||
|
||||
|
||||
|
||||
|
||||
**4. ֱ<EFBFBD>ӽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**4. 直接解决方案**
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>ǹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>棬<EFBFBD>жϵ<EFBFBD>ǰ<EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݲ<EFBFBD>ͬ<EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD>в<EFBFBD>ͬ<EFBFBD>Ĵ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ҷ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ͬ<EFBFBD><EFBFBD>״̬ת<EFBFBD>ơ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>е<EFBFBD>ʵ<EFBFBD><EFBFBD>ϸ<EFBFBD>ڶ<EFBFBD><EFBFBD>ŵ<EFBFBD><EFBFBD>ͻ<EFBFBD><EFBFBD>࣬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>״̬<EFBFBD><EFBFBD>ʱ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫȥ<EFBFBD>Ŀͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ĵ<EFBFBD><EFBFBD>롣
|
||||
在糖果机的每个操作函数里面，判断当前的状态，根据不同的状态进行不同的处理，并且发生不同的状态转移。这种解决方案把所有的实现细节都放到客户类，这样在新增状态的时候就要去修改客户类的代码。
|
||||
|
||||
|
||||
|
||||
|
||||
**5. ʹ<EFBFBD><EFBFBD>״̬ģʽ<EFBFBD>Ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**
|
||||
**5. 使用状态模式的解决方案**
|
||||
|
||||
״̬<EFBFBD><EFBFBD>ת<EFBFBD>Ʊ<EFBFBD><EFBFBD>Ƶ<EFBFBD>״̬<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>棬<EFBFBD>ͻ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ÿ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֻ<EFBFBD><EFBFBD>Ҫί<EFBFBD>и<EFBFBD>״̬<EFBFBD>༴<EFBFBD>ɣ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫ֪<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ǰ<EFBFBD><EFBFBD>ʲô״̬<EFBFBD>Լ<EFBFBD>״̬ʱ<EFBFBD><EFBFBD><EFBFBD>ν<EFBFBD><EFBFBD><EFBFBD>ת<EFBFBD>Ƶġ<EFBFBD>
|
||||
状态的转移被移到状态类里面，客户类的每个操作只需要委托给状态类即可，而不需要知道当前是什么状态以及状态时如何进行转移的。
|
||||
|
||||
|
||||
**6. <EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʵ<EFBFBD><EFBFBD>**
|
||||
**6. 代码实现**
|
||||
|
||||
```java
|
||||
public interface State {
|
||||
/**
|
||||
* Ͷ<EFBFBD><EFBFBD>25 <20><>Ǯ
|
||||
* 投入25 分钱
|
||||
*/
|
||||
void insertQuarter();
|
||||
|
||||
/**
|
||||
* <EFBFBD>˻<EFBFBD>25 <20><>Ǯ
|
||||
* 退回25 分钱
|
||||
*/
|
||||
void ejectQuarter();
|
||||
|
||||
/**
|
||||
* ת<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
* 转动曲柄
|
||||
*/
|
||||
void turnCrank();
|
||||
|
||||
/**
|
||||
* <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ǹ<EFBFBD>
|
||||
* 发放糖果
|
||||
*/
|
||||
void dispense();
|
||||
}
|
||||
@ -1667,7 +1668,7 @@ public class GumballMachineTestDrive {
|
||||
}
|
||||
}
|
||||
```
|
||||
<EFBFBD><EFBFBD><EFBFBD>н<EFBFBD><EFBFBD><EFBFBD>
|
||||
运行结果
|
||||
```html
|
||||
You insert a quarter
|
||||
You turned...
|
||||
@ -1696,34 +1697,34 @@ You turned, but there are no gumballs
|
||||
No gumball dispensed
|
||||
```
|
||||
|
||||
# <EFBFBD><EFBFBD> 11 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 11 章 代理模式
|
||||
|
||||
# <EFBFBD><EFBFBD> 12 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD>ģʽ
|
||||
# 第 12 章 复合模式
|
||||
|
||||
## 12.1 MVC
|
||||
|
||||
**<EFBFBD><EFBFBD>ͳ MVC**
|
||||
**传统 MVC**
|
||||
|
||||
<EFBFBD><EFBFBD>ͼʹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD>ģ<EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD>˹۲<EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD>˲<EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD>
|
||||
视图使用组合模式，模型使用了观察者模式，控制器使用了策略模式。
|
||||
|
||||
|
||||
|
||||
|
||||
**Web <EFBFBD>е<EFBFBD> MVC**
|
||||
**Web 中的 MVC**
|
||||
|
||||
ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD>ù۲<EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD>
|
||||
模式不再使用观察者模式。
|
||||
|
||||
|
||||
|
||||
|
||||
# <EFBFBD><EFBFBD> 13 <EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<C4A3>ദ
|
||||
# 第 13 章 与设计模式相处
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD>壺<EFBFBD><EFBFBD>ij **<EFBFBD>龳** <20>£<EFBFBD><C2A3><EFBFBD><EFBFBD><EFBFBD>ij **<EFBFBD><EFBFBD><EFBFBD><EFBFBD>** <20><>ij<EFBFBD><C4B3> **<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>**<2A><>
|
||||
定义：在某 **情境** 下，针对某 **问题** 的某种 **解决方案**。
|
||||
|
||||
<EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD>ܵ<EFBFBD><EFBFBD>´<EFBFBD><EFBFBD>뱻<EFBFBD><EFBFBD><EFBFBD>ȹ<EFBFBD><EFBFBD>̻<EFBFBD><EFBFBD><EFBFBD>Ӧ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ľ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ɹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ҫģʽ<EFBFBD>ĵط<EFBFBD><EFBFBD><EFBFBD>ʹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
过度使用设计模式可能导致代码被过度工程化，应该总是用最简单的解决方案完成工作，并在真正需要模式的地方才使用它。
|
||||
|
||||
<EFBFBD><EFBFBD>ģʽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>õĽ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>⡣<EFBFBD><EFBFBD>Ҫ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ<EFBFBD>˾<EFBFBD><EFBFBD>治Ҫʹ<EFBFBD><EFBFBD><EFBFBD><EFBFBD>Щ<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
|
||||
反模式：不好的解决方案来解决一个问题。主要作用是为了警告不要使用这些解决方案。
|
||||
|
||||
ģʽ<EFBFBD><EFBFBD><EFBFBD>ࣺ
|
||||
模式分类：
|
||||
|
||||
|
||||
|
||||
|
||||
# <EFBFBD><EFBFBD> 14 <EFBFBD><EFBFBD> ʣ<>µ<EFBFBD>ģʽ
|
||||
# 第 14 章 剩下的模式
|
||||
|
||||
Reference in New Issue
Block a user