工厂模式（Factory Pattern）笔记

[Wang-Shengyuan]

除了课上所讲的结构型模式和行为型模式外，OOP的设计模式还有创建型模式、并发型模式和线程池模式等。工厂模式属于创建型模式，分为三类：简单工厂模式、工厂方法模式、抽象工厂模式

!(https://img-blog.csdn.net/20140304233530984)

简单工厂
具体情形：有一个肥皂厂，生产各种肥皂，有舒肤佳，夏士莲，娜爱斯等。

#include <iostream>
using namespace std;
enum PRODUCTTYPE {SFJ,XSL,NAS};
class soapBase
{
	public:
	virtual ~soapBase(){};
	virtual void show() = 0;
};
 
class SFJSoap:public soapBase
{
	public:
	void show() {cout<<"SFJ Soap!"<<endl;}
};
 
class XSLSoap:public soapBase
{
	public:
	void show() {cout<<"XSL Soap!"<<endl;}
};
 
class NASSoap:public soapBase
{
	public:
	void show() {cout<<"NAS Soap!"<<endl;}
};
 
class Factory
{
	public:
	soapBase * creatSoap(PRODUCTTYPE type)
	{
		switch(type)
		{
			case SFJ: 
				return new SFJSoap();
				break;
			case XSL:
				return new XSLSoap();
				break;
			case NAS:
				return new NASSoap();
				break;
			default:break;
		}
		
	}
};
 
int main()
{
	Factory factory;
	soapBase* pSoap1 = factory.creatSoap(SFJ);
	pSoap1->show();
	soapBase* pSoap2 = factory.creatSoap(XSL);
	pSoap2->show();
	soapBase* pSoap3 = factory.creatSoap(NAS);
	pSoap3->show();
	delete pSoap1;
	delete pSoap2;
	delete pSoap3;
	return 0;
}

工厂方法模式
具体情形：独立每个生产线，每个生产线只生产一种肥皂。

#include <iostream>
using namespace std;
enum SOAPTYPE {SFJ,XSL,NAS};
 
class soapBase
{
	public:
	virtual ~soapBase(){};
	virtual void show() = 0;
};
 
class SFJSoap:public soapBase
{
	public:
	void show() {cout<<"SFJ Soap!"<<endl;}
};
 
class XSLSoap:public soapBase
{
	public:
	void show() {cout<<"XSL Soap!"<<endl;}
};
 
class NASSoap:public soapBase
{
	public:
	void show() {cout<<"NAS Soap!"<<endl;}
};
 
class FactoryBase
{
	public:
	virtual soapBase * creatSoap() = 0;
};
 
class SFJFactory:public FactoryBase
{
	public:
	soapBase * creatSoap()
	{
		return new SFJSoap();
	}
};
 
class XSLFactory:public FactoryBase
{
	public:
	soapBase * creatSoap()
	{
		return new XSLSoap();
	}
};
 
class NASFactory:public FactoryBase
{
	public:
	soapBase * creatSoap()
	{
		return new NASSoap();
	}
};
 
 
 
int main()
{
	SFJFactory factory1;
	soapBase* pSoap1 = factory1.creatSoap();
	pSoap1->show();
	XSLFactory factory2;
	soapBase* pSoap2 = factory2.creatSoap();
	pSoap2->show();
	NASFactory factory3;
	soapBase* pSoap3 = factory3.creatSoap();
	pSoap3->show();
	delete pSoap1;
	delete pSoap2;
	delete pSoap3;
	return 0;
}

抽象工厂模式
具体情形：这个肥皂厂发现搞牙膏也很赚钱，决定做牙膏。牙膏有高档低档，肥皂也是。现在搞两个厂房，一个生产低档的牙膏和肥皂，一个生产高档的牙膏和肥皂。比如，厂房一生产中华牙膏、娜爱斯肥皂，厂房二生产黑人牙膏和舒肤佳牙膏

#include <iostream>
using namespace std;
enum SOAPTYPE {SFJ,XSL,NAS};
enum TOOTHTYPE {HR,ZH};
 
class SoapBase
{
	public:
	virtual ~SoapBase(){};
	virtual void show() = 0;
};
 
class SFJSoap:public SoapBase
{
	public:
	void show() {cout<<"SFJ Soap!"<<endl;}
};
 
class NASSoap:public SoapBase
{
	public:
	void show() {cout<<"NAS Soap!"<<endl;}
};
 
class ToothBase
{
	public:
	virtual ~ToothBase(){};
	virtual void show() = 0;
};
 
class HRTooth:public ToothBase
{
	public:
	void show() {cout<<"Hei ren Toothpaste!"<<endl;}
};
 
class ChinaTooth:public ToothBase
{
	public:
	void show() {cout<<"China Toothpaste!"<<endl;}
};
 
class FactoryBase
{
	public:
	virtual SoapBase * creatSoap() = 0;
	virtual ToothBase * creatToothpaste() = 0;
};
 
class FactoryA :public FactoryBase
{
	public:
	SoapBase * creatSoap()
	{
		return new SFJSoap();
	}
	
	ToothBase * creatToothpaste()
	{
		return new HRTooth();
	}
};
 
class FactoryB :public FactoryBase
{
	public:
	SoapBase * creatSoap()
	{
		return new NASSoap();
	}
	
	ToothBase * creatToothpaste()
	{
		return new ChinaTooth();
	}
};
 
 
int main()
{
	FactoryA factory1;
	FactoryB factory2;
	SoapBase *pSoap1 = NULL;
	ToothBase *pToothpaste1 = NULL;
	pSoap1 = factory1.creatSoap();
	pToothpaste1 = factory1.creatToothpaste();
	pSoap1->show();
	pToothpaste1->show();
	
	SoapBase *pSoap2 = NULL;
	ToothBase *pToothpaste2 = NULL;
	pSoap2 = factory2.creatSoap();
	pToothpaste2 = factory2.creatToothpaste();
	pSoap2->show();
	pToothpaste2->show();
	
	delete pSoap1;
	delete pSoap2;
	delete pToothpaste1;
	delete pToothpaste2;
	
	return 0;
}

工厂模式的组成
1)抽象工厂角色：这是工厂方法模式的核心，它与应用程序无关。是具体工厂角色必须实现的接口或者必须继承的父类。
2)具体工厂角色：它含有和具体业务逻辑有关的代码。由应用程序调用以创建对应的具体产品的对象。
3)抽象产品角色：它是具体产品继承的父类或者是实现的接口。
4)具体产品角色：具体工厂角色所创建的对象就是此角色的实例。

适用场合

在程序中，需要创建的对象很多，导致对象的new操作多且杂时，需要使用简单工厂模式；
由于对象的创建过程是我们不需要去关心的，而我们注重的是对象的实际操作，所以，我们需要分离对象的创建和操作两部分，如此，方便后期的程序扩展和维护。

[Wang-Shengyuan]

第一幅UML图上传疑有问题，可点击链接查看