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;
}