15 大话设计模式C++实现之抽象工厂模式

/*
抽象工厂模式：
提供一个创建一系列相关或相互依赖对象的接口，而无需指定他们具体的类
*/

/*
实例：不同客户的数据库管理采用不同的数据库完成，不同的数据库在语法上存在差异，因此需要
解除用户和具体数据库之间的耦合（即业务逻辑与数据访问的解耦）,避免向不同类型的客户提供支持时的代码复用
*/

#include<iostream>
#include<string>

using namespace std;

//IDepartment接口，用于客户端访问，解除与具体数据库的访问的耦合
class IDepartment
{
public:
virtual void Insert(IDepartment* department) = 0;
virtual IDepartment* GetDepartment(int id) = 0;
};

//SqlseverDepartment类，用于访问SQL sever的Department
class SqlServerDepartment : public IDepartment
{
public:
   virtual void Insert(IDepartment* department)
   {
       cout << "在SQL Server中给Department增加一条记录" << endl;
   }
   IDepartment* GetDepartment(int id)
   {
       cout << "在SQL Server中根据ID得到的Department记录" << endl;
       return NULL;
   }
};

//AccessDepartment类，用于访问Access的Department
class AccessDepartment : public IDepartment
{
public:
   virtual void Insert(IDepartment* department)
   {
       cout << "在Access中给Department表增加一条记录" << endl;
   }
   virtual IDepartment* GetDepartment(int id)
   {
       cout << "在Access中根据ID得到Department表一条记录" << endl;
       return NULL;
   }
};

//IUer接口，用于客户端访问，解除与具体数据库访问的耦合
class IUser
{
public:
virtual void Insert(IUser* user) = 0;
virtual IUser* GetUser(int id) = 0;
};

class SqlseverUser : public IUser
{
public:
   virtual void Insert(IUser* user)
   {
       cout << "在SQL中给User增加一条记录！" << endl;
   }
   virtual IUser* GetUser(int id)
   {
       IUser *sq = new SqlseverUser;
       return sq;
   }
};

class AccessUser : public IUser
{
public:
   AccessUser()
   {
       cout << "AccessUser构造函数" << endl;
   }
   virtual void Insert(IUser* user)
   {
       cout << "在ACESS中给User增加一条记录！" << endl;
   }
   virtual IUser* GetUser(int id)
   {
       cout << "在ACESS中根据ID得到一条user表记录" << endl;
       IUser *sa = new AccessUser;
       return sa;
   }
};

//定义工厂类接口
//工厂方法模式是定义一个用于创建对象的接口，让子类决定具体实例化哪一个对象，可以利用父类指针指向子类对象
class IFactory
{
public:
virtual IUser* CreateUser() = 0;
virtual IDepartment* CreateDepartment() = 0;
};

class SqlseverFactory : public IFactory
{
public:
   virtual IUser* CreateUser()
   {
       return new SqlseverUser;
   }
   virtual IDepartment* CreateDepartment()
   {
       return new SqlServerDepartment;
   }
};

class AccessFactory : public IFactory
{
public:
   AccessFactory()
   {
       cout << "创建accessfactory对象" << endl;
   }
   virtual IUser* CreateUser()
   {
       cout << "创建AccessUser对象" << endl;
       return new AccessUser;
   }
   virtual IDepartment* CreateDepartment()
   {
       cout << "创建AccessDepartment对象" << endl;
       return new AccessDepartment;
   }
};

void Client()
{
   IUser *user = NULL;
   IDepartment * dept = NULL;
   IFactory *fac = new AccessFactory();
   IUser *iu = fac->CreateUser(); //iu指向accessuser对象
   iu->Insert(user);
   iu->GetUser(1);

   IDepartment *id = fac->CreateDepartment();
   id->Insert(dept);
   id->GetDepartment(1);
   if (iu != NULL)
   {
       free(iu);
       iu = NULL;
   }
   if (fac != NULL)
   {
       free(fac);
       fac = NULL;
   }
}

int main()
{
   Client();
   system("pause");
   return 0;
}

15 大话设计模式C++实现之抽象工厂模式

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