设计模式C++实现十一：抽象工厂模式

抽象工厂模式（Abstract Factory）：提供一个创建一系列相关或者相互依赖对象的接口，而无需指定他们具体的类。

优点：便于交换产品系统，由于具体工厂类，在一个应用中只需要初始化的时候出现一次，这就使得改变一个应用的具体工厂变得非常容易，只需要改变具体工厂即可以使用不同的产品配置。它让具体的创建实例过程与客户端分离，客户端是通过他们的抽象接口操作实例，产品的具体类名也被具体工厂实现分离，不会出现在客户端代码中。

#ifndef ABSTRACTFACTORY_H
#define ABSTRACTFACTORY_H
#include<iostream>
#include<string>
using namespace std;

class IDepartment
{
	int id;
	string depname;
public:
	virtual void Insert(IDepartment * dp)=0;
	virtual IDepartment * GetDepartment(int id)=0;
};

class SqlserverDepartment :public IDepartment
{
public:
	void Insert(IDepartment * dp) ;
	IDepartment * GetDepartment(int id) ;
};

void SqlserverDepartment::Insert(IDepartment * dp)
{
	cout << "在SQL Server 中给Department表增加一条记录。\n";
}
IDepartment * SqlserverDepartment::GetDepartment(int id)
{
	cout << "在SQL Server 中根据ID得到Department表的一条记录。\n";
	return NULL;
}
class AccessDepartment :public IDepartment
{
public:
	void Insert(IDepartment * dp);
	IDepartment * GetDepartment(int id);
};
void AccessDepartment::Insert(IDepartment * dp)
{
	cout << "在Access 中给Department表增加一条记录。\n";
}
IDepartment * AccessDepartment::GetDepartment(int id)
{
	cout << "在Access 中根据ID得到Department表的一条记录。\n";
	return NULL;
}
class IUser
{
public:
	virtual void Insert(IUser *) = 0;
	virtual IUser * GetUser(int id) = 0;
};
class SqlserverUser :public IUser
{
public:
	void Insert(IUser *);
	IUser * GetUser(int id);
};
void SqlserverUser::Insert(IUser * in)
{
	cout << "在SQL Server中给User表增加一条记录。\n";
}

IUser * SqlserverUser::GetUser(int id)
{
	cout << "在SQL Server 中根据ID得到User表中的一条记录。\n";
	return NULL;
}

class AccessUser :public IUser
{
public:
	void Insert(IUser *);
	IUser * GetUser(int id);
};
void AccessUser::Insert(IUser * in)
{
	cout << "在Access给User表增加一条记录。\n";
}

IUser * AccessUser::GetUser(int id)
{
	cout << "在Access中根据ID得到User表中的一条记录。\n";
	return NULL;
}
class IFactory
{
public:
	virtual IUser * CreateUser() = 0;
	virtual IDepartment * CreateDepartment() = 0;
};

class SqlserverFactory :public IFactory
{
public:
	IUser * CreateUser();
	IDepartment * CreateDepartment();
};
IUser * SqlserverFactory::CreateUser()
{
	return new SqlserverUser;
}
IDepartment * SqlserverFactory::CreateDepartment()
{
	return new SqlserverDepartment;
}
class AccessFactory :public IFactory
{
public:
	IUser * CreateUser();
	IDepartment * CreateDepartment();
};
IUser * AccessFactory::CreateUser()
{
	return new AccessUser;
}
IDepartment * AccessFactory::CreateDepartment()
{
	return new AccessDepartment;
}
#endif

#include"AbstractFactory.h"
int main()
{
	IUser * userI = new SqlserverUser;
	IDepartment * dptI = new SqlserverDepartment;

	IFactory * factory = new SqlserverFactory;

	IUser * user = factory->CreateUser();
	//IDepartment * dpt = factory->CreateDepartment();
	user->Insert(userI);
	user->GetUser(1);

	IDepartment * dpt = factory->CreateDepartment();
	dpt->Insert(dptI);
	dpt->GetDepartment(1);

	IDepartment * AdptI = new AccessDepartment;

	IFactory * Afactory = new AccessFactory;
	IDepartment * IDf=Afactory->CreateDepartment();
	IDf->Insert(AdptI);
	IDf->GetDepartment(1);

	IUser *AuserI = new AccessUser;
	IUser * AUf = Afactory->CreateUser();
	AUf->Insert(AuserI);
	AUf->GetUser(1);
	return 0;
}