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。
实际应用
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、CGrape.h、CStrawberry.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_
/************************************************************************/
/* 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_
/************************************************************************/
/* 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、CGrapeGardener.h、CStrawberryGardener.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_
/************************************************************************/
/* 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_
/************************************************************************/
/* 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;
}
