作用:
定義一個(gè)用于創(chuàng)建對(duì)象的接口，讓子類(lèi)決定實(shí)例化哪一個(gè)類(lèi)。Factory Method 使一個(gè)類(lèi)的實(shí)例化延遲到其子類(lèi)。
UML結(jié)構(gòu)圖:
抽象基類(lèi):
1)Product:創(chuàng)建出來(lái)的對(duì)象的抽象基類(lèi).
2)Factory創(chuàng)建對(duì)象的工廠方法的抽象基類(lèi).
接口函數(shù):
1)Creator::FactoryMethod:純虛函數(shù),由派生類(lèi)實(shí)現(xiàn),創(chuàng)建出對(duì)應(yīng)的Product.
解析:
在這個(gè)模式中,有兩個(gè)抽象基類(lèi),一個(gè)是Product為創(chuàng)建出來(lái)的對(duì)象的抽象基類(lèi),一個(gè)是Factory是工廠的抽象基類(lèi),在互相協(xié)作的時(shí)候都是由相應(yīng)的Factory派生類(lèi)來(lái)生成Product的派生類(lèi),也就是說(shuō)如果要新增一種Product那么也要對(duì)應(yīng)的新增一個(gè)Factory,創(chuàng)建的過(guò)程委托給了這個(gè)Factory.也就是說(shuō)一個(gè)Factory和一個(gè)Product是一一對(duì)應(yīng)的關(guān)系.
備注:
設(shè)計(jì)模式的演示圖上把Factory類(lèi)命名為Creator,下面的實(shí)現(xiàn)沿用了這個(gè)命名.
演示實(shí)現(xiàn):
1)Factory.h
/**//********************************************************************
????created:????2006/06/30
????filename:?????Factory.h
????author:????????李創(chuàng)
????????????????http://m.shnenglu.com/converse/
????purpose:????Factory模式的演示代碼
*********************************************************************/
#ifndef?FACTORY_H
#define?FACTORY_H
class?Product
{
public:
????Product(){}
????virtual?~Product(){}
};
class?ConcreateProduct
????:?public?Product
{
public:
????ConcreateProduct();
????virtual?~ConcreateProduct();
};
class?Creator
{
public:
????Creator(){}
????virtual?~Creator(){}
????void?AnOperation();
protected:
????virtual?Product*?FactoryMethod()?=?0;
};
class?ConcreateCreator
????:?public?Creator
{
public:
????ConcreateCreator();
????virtual?~ConcreateCreator();
protected:
????virtual?Product*?FactoryMethod();
};
#endif
2)Factory.cpp
/**//********************************************************************
????created:????2006/06/30
????filename:?????Factory.cpp
????author:????????李創(chuàng)
????????????????http://m.shnenglu.com/converse/
????purpose:????Factory模式的演示代碼
*********************************************************************/
#include?"Factory.h"
#include?<iostream>
using?namespace?std;
ConcreateProduct::ConcreateProduct()
{
????std::cout?<<?"construction?of?ConcreateProduct\n";
}
ConcreateProduct::~ConcreateProduct()
{
????std::cout?<<?"destruction?of?ConcreateProduct\n";
}
void?Creator::AnOperation()
{
????Product*?p?=?FactoryMethod();
????std::cout?<<?"an?operation?of?product\n";
}
ConcreateCreator::ConcreateCreator()
{
????std::cout?<<?"construction?of?ConcreateCreator\n";
}
ConcreateCreator::~ConcreateCreator()
{
????std::cout?<<?"destruction?of?ConcreateCreator\n";
}
Product*?ConcreateCreator::FactoryMethod()
{
????return?new?ConcreateProduct();
}
3)Main.cpp(測(cè)試代碼)
/**//********************************************************************
????created:????2006/06/30
????filename:?????Main.cpp
????author:????????李創(chuàng)
????????????????http://m.shnenglu.com/converse/
????purpose:????測(cè)試Factory模式的代碼
*********************************************************************/
#include?"Factory.h"
#include?<stdlib.h>
int?main(int?argc,char*?argv[])
{
????Creator?*p?=?new?ConcreateCreator();
????p->AnOperation();
????delete?p;
????system("pause");
????return?0;
}