第15章抽象工厂模式

一概念

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，而无需指定它们具体的类。

二包含的角色

抽象工厂：它里面应该包含所有的产品创建的抽象方法
具体工厂：具体工厂，创建具有特定实现的产品对象
抽象产品：他们都有可能有两种不同的实现
具体产品

三优势

抽象工厂模式是对工厂方法模式的改进。用于处理产品不只有一类的情况（工厂方法模式下，产品只有User这一类，而抽象工厂模式下，产品包括User和Department两类）。

四 C++代码实现

#include "pch.h"
#include <iostream>
#include <string>
using namespace std;

//数据库表项：User 与工厂模式无关
class User
{
public:
    void SetId(const int id)
    {
        this->_id = id;
    }
    int GetId()
    {
        return this->_id;
    }
    void SetName(const string name)
    {
        this->_name = name;
    }
    string GetName()
    {
        return this->_name;
    }
private:
    int _id;
    string _name;
};

//数据库表项 Department 与工厂模式无关
class Department
{
public:
    void SetId(const int id)
    {
        this->_id = id;
    }
    int GetId()
    {
        return this->_id;
    }
    void SetName(const string name)
    {
        this->_deptName = name;
    }
    string GetName()
    {
        return this->_deptName;
    }
private:
    int _id;
    string _deptName;
};

//抽象产品A: IUser
class IUser
{
public:
    virtual void Insert(User user) = 0;
    virtual User* GetUser(int id) = 0;
};
//具体产品A1 SqlserverUser
class SqlserverUser : public IUser
{
public:
    void Insert(User user)
    {
        cout << "在SQL server中给User表增加一条记录" << endl;
    }
    User* GetUser(int id)
    {
        cout << "在SQL server中根据ID得到User表一条记录" << endl;
        return NULL;
    }
};
//具体产品A2 AccessUser
class AccessUser : public IUser 
{
public:
    void Insert(User user)
    {
        cout << "在Access 中给User表增加一条记录" << endl;
    }
    User* GetUser(int id)
    {
        cout << "在Access 中根据ID得到User表一条记录" << endl;
        return NULL;
    }
};


//抽象产品B: IDepartment
class IDepartment
{
public:
    virtual void Insert(Department department) = 0;
    virtual Department* GetUser(int id) = 0;
};

//具体产品B1 SqlserverDepartment
class SqlserverDepartment : public IDepartment
{
public:
    void Insert(Department department)
    {
        cout << "在SQL server中给Department表增加一条记录" << endl;
    }
    Department* GetUser(int id)
    {
        cout << "在SQL server中根据ID得到Department表一条记录" << endl;
        return NULL;
    }
};
//具体产品B2 AccessDepartment
class AccessDepartment : public IDepartment
{
public:
    void Insert(Department department)
    {
        cout << "在Access 中给Department表增加一条记录" << endl;
    }
    Department* GetUser(int id)
    {
        cout << "在Access 中根据ID得到Department表一条记录" << endl;
        return NULL;
    }
};

//抽象工厂 
//抽象工厂接口,它里面应该包含所有的产品创建的抽象方法
class IFactory
{
public:
    virtual IUser* createUser() = 0;
    virtual IDepartment* createDepartment() = 0;

};

//具体工厂1，创建具有特定实现的产品对象
class SqlServerFactory : public IFactory
{
public:
    IUser* createUser()
    {
        IUser* puser;
        puser = new SqlserverUser();
        return puser;
    }
    IDepartment* createDepartment()
    {
        IDepartment* pdepartment;
        pdepartment = new SqlserverDepartment();
        return pdepartment;
    }
};

class AccessFactory : public IFactory
{
public:
    IUser* createUser()
    {
        IUser* puser;
        puser = new AccessUser();
        return puser;
    }
    IDepartment* createDepartment()
    {
        IDepartment* pdepartment;
        pdepartment = new AccessDepartment();
        return pdepartment;
    }
};

int main()
{
    User user;
    Department department;

    //只需要确定实例化哪一个数据库访问对象给factory
    IFactory* factory = new AccessFactory;

    //则此时已与具体的数据库访问解除了依赖
    IUser* iu = factory->createUser();

    iu->Insert(user);
    iu->GetUser(1);

    //则此时已与具体的数据库访问解除了依赖
    IDepartment* id = factory->createDepartment();
    id->Insert(department);
    id->GetUser(1);

    return 0;
}

参考资料：
1 《大话设计模式C++实现-第15章-抽象工厂模式》 https://blog.csdn.net/xiqingnian/article/details/41181995
2 《大话设计模式》程杰著

第15章抽象工厂模式

猜你喜欢