【C++】Chapter5：工厂方法模式
先说下简单工厂和工厂方法的区别：
简单工厂模式的最大优点在于工厂类中包含了必要的逻辑判断，根据客户端的选择条件动态实例化相关的类，对于客户端来说，去除了与具体产品的依赖。
工厂方法模式（Factory Method），定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到其子类。
工厂方法模式实现时，客户端需要决定实例化哪一个工厂来实现产品类，选择判断的问题还是存在的，也就是说，工厂方法把简单工厂的内部逻辑判断移到了客户端代码来进行。想要加功能，本来是改工厂类的，而现在是修改客户端。
工程结构：
（1）抽象产品类
IFruit.h
（2）抽象工厂类
IFruitGardener.h
（3）具体产品类
CApple.h
CGrape.h
CStrawberry.h
（4）具体工厂类
CAppleGardener.h
CGrapeGardener.h
CStrawberryGardener.h
（5）客户端
FactoryMethodApplication.cpp
（1）抽象产品类
IFruit.h
/************************************************************************/ /* 抽象水果类(abstract Product) */ /************************************************************************/ #ifndef _IFRUIT_H_ #define _IFRUIT_H_ #include <string> #include <iostream> using namespace std; class IFruit { public: virtual void grow() = 0; virtual void harvest() = 0; virtual void plant() = 0; }; #endif _IFRUIT_H_
（2）抽象工厂类
IFruitGardener.h
/************************************************************************/ /* 抽象水果园丁类(abstract Factory) */ /************************************************************************/ #ifndef _IFRUIT_GARDENER_H_ #define _IFRUIT_GARDENER_H_ #include "IFruit.h" class IFruitGardener { public: virtual IFruit* Factory() = 0; }; #endif _IFRUIT_GARDENER_H_
（3）具体产品类
CApple.h
/************************************************************************/ /* 具体的苹果类(Concrete Product) */ /************************************************************************/ #ifndef _APPLE_H_ #define _APPLE_H_ #include "IFruit.h" class CApple : public IFruit { public: void grow() { cout << "Apple is growing..." << endl; }; void harvest() { cout << "Apple has been harvested." << endl; }; void plant() { cout << "Apple has been planted." << endl; }; int GetTreeAge() { return m_iAppleTreeAge; }; void SetTreeAge(const int iAge) { m_iAppleTreeAge = iAge; } private: int m_iAppleTreeAge; }; #endif _APPLE_H_
CGrape.h
/************************************************************************/ /* 具体的葡萄类(Concrete Product) */ /************************************************************************/ #ifndef _GRAPE_H_ #define _GRAPE_H_ #include "IFruit.h" class CGrape : public IFruit { public: void grow() { cout << "Grape is growing..." << endl; }; void harvest() { cout << "Grape has been harvested." << endl; }; void plant() { cout << "Grape has been planted." << endl; }; bool GetSeedless() { return m_bSeedless; }; void SetSeedless(const bool bSeedless) { m_bSeedless = bSeedless; }; private: bool m_bSeedless; }; #endif _GRAPE_H_
CStrawberry.h
/************************************************************************/ /* 具体的草莓类(Concrete Product) */ /************************************************************************/ #ifndef _STRAWBERRY_H_ #define _STRAWBERRY_H_ #include "IFruit.h" class CStrawberry : public IFruit { public: void grow() { cout << "Strawberry is growing..." << endl; }; void harvest() { cout << "Strawberry has been harvested." << endl; }; void plant() { cout << "Strawberry has been planted." << endl; }; }; #endif _STRAWBERRY_H_
（4）具体工厂类
CAppleGardener.h
/************************************************************************/ /* 具体的苹果园丁类(Concrete Factory) */ /************************************************************************/ #ifndef _APPLE_GARDENER_H_ #define _APPLE_GARDENER_H_ #include "IFruitGardener.h" #include "CApple.h" class CAppleGardener : public IFruitGardener { public: CAppleGardener():m_pApple(NULL){}; IFruit* Factory() { if (NULL == m_pApple) { m_pApple = new CApple(); } return m_pApple; }; private: CApple* m_pApple; }; #endif _APPLE_GARDENER_H_
CGrapeGardener.h
/************************************************************************/ /* 具体的葡萄园丁类(Concrete Factory) */ /************************************************************************/ #ifndef _GRAPE_GARDENER_H_ #define _GRAPE_GARDENER_H_ #include "IFruitGardener.h" #include "CGrape.h" class CGrapeGardener : public IFruitGardener { public: CGrapeGardener():m_pGrape(NULL){}; IFruit* Factory() { if (NULL == m_pGrape) { m_pGrape = new CGrape(); } return m_pGrape; }; private: CGrape* m_pGrape; }; #endif _GRAPE_GARDENER_H_
CStrawberryGardener.h
/************************************************************************/ /* 具体的草莓园丁类(Concrete Factory) */ /************************************************************************/ #ifndef _STRAWBERRY_GARDENER_H_ #define _STRAWBERRY_GARDENER_H_ #include "IFruitGardener.h" #include "CStrawberry.h" class CStrawberryGardener : public IFruitGardener { public: CStrawberryGardener():m_pStrawberry(NULL){}; IFruit* Factory() { if (NULL == m_pStrawberry) { m_pStrawberry = new CStrawberry(); } return m_pStrawberry; }; private: CStrawberry* m_pStrawberry; }; #endif _STRAWBERRY_GARDENER_H_
（5）客户端
FactoryMethodApplication.cpp
// FactoryMethodApplication.cpp : 定义控制台应用程序的入口点。 // #include "stdafx.h" #include <Windows.h> #include "IFruitGardener.h" #include "CAppleGardener.h" #include "CGrapeGardener.h" #include "CStrawberryGardener.h" int _tmain(int argc, _TCHAR* argv[]) { static IFruitGardener* pFruitFactory1 = NULL; static IFruitGardener* pFruitFactory2 = NULL; static IFruit* pFruit1 = NULL; static IFruit* pFruit2 = NULL; pFruitFactory1 = new CAppleGardener(); if (NULL != pFruitFactory1) { pFruit1 = pFruitFactory1->Factory(); if (NULL != pFruit1) { pFruit1->grow(); pFruit1->harvest(); pFruit1->plant(); } } pFruitFactory2 = new CGrapeGardener(); if (NULL != pFruitFactory2) { pFruit2 = pFruitFactory2->Factory(); if (NULL != pFruit2) { pFruit2->grow(); pFruit2->harvest(); pFruit2->plant(); } } Sleep(10000); return 0; }