当DP遇见Py(十一) -- 抽象工厂模式

目录
  1. 定义：
  2. 类图：
  3. 类型：创建型
  4. 实例：
    1. C++ 实现
    2. Python 实现
  5. Tips:

定义：

提供一个创建一系列相关或相互依赖对象的接口，而无需指定它们的类。

类图：

类型：创建型

实例：

提供对不同的数据库访问的支持

C++ 实现

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#include <iostream>
#include <string>
using namespace std;

class IUser
{
public:
    virtual void getUser()=0;
    virtual void setUser()=0;
};

class SqlUser:public IUser
{
public:
    void getUser()
    {
        cout<<"在sql中返回user"<<endl;
    }
    void setUser()
    {
        cout<<"在sql中设置user"<<endl;
    }
};

class AccessUser:public IUser
{
public:
    void getUser()
    {
        cout<<"在Access中返回user"<<endl;
    }
    void setUser()
    {
        cout<<"在Access中设置user"<<endl;
    }
};

class IDepartment
{
public:
    virtual void getDepartment()=0;
    virtual void setDepartment()=0;
};

class SqlDepartment:public IDepartment
{
public:
    void getDepartment()
    {
        cout<<"在sql中返回Department"<<endl;
    }
    void setDepartment()
    {
        cout<<"在sql中设置Department"<<endl;
    }
};

class AccessDepartment:public IDepartment
{
public:
    void getDepartment()
    {
        cout<<"在Access中返回Department"<<endl;
    }
    void setDepartment()
    {
        cout<<"在Access中设置Department"<<endl;
    }
};

class IFactory
{
public:
    virtual IUser *createUser()=0;
    virtual IDepartment *createDepartment()=0;
};

class SqlFactory:public IFactory
{
public:
    IUser *createUser() 
    {
        return new SqlUser();
    }
    IDepartment *createDepartment() 
    {
        return new SqlDepartment();
    }
};

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

int main()
{
    IFactory *factory=new SqlFactory();
    IUser *user = user=factory->createUser();
    IDepartment * department = factory->createDepartment();
    
    user->getUser();
    user->setUser();
    department->getDepartment();
    department->setDepartment();

    return 0;
}

Python 实现

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# -*- coding=utf-8 -*-

class SqlUser:
    def getUser(self):
        print "在sql中返回user"
    def setUser(self):
        print "在sql中设置user"

class AccessUser:
    def getUser(self):
        print "在Access中返回user"
    def setUser(self):
        print "在Access中设置user"

class SqlDepartment:
    def getDepartment(self):
        print "在sql中返回Department"
    def setDepartment(self):
        print "在sql中设置Department"

class AccessDepartment:
    def getDepartment(self):
        print "在Access中返回Department"
    def setDepartment(self):
        print "在Access中设置Department"

class SqlFactory:
    def createUser(self):
        return SqlUser()
    def createDepartment(self):
        return SqlDepartment()

class AccessFactory:
    def createUser(self):
        return AccessUser()
    def createDepartment(self):
        return AccessDepartment()

if __name__ == '__main__':
    factory = SqlFactory()
    user = factory.createUser()
    department = factory.createDepartment()

    user.getUser()
    user.setUser()
    department.getDepartment()
    department.setDepartment()

Tips:

Python实现的抽象工厂模式相比与C++来说并没有什么显著特点。抽象工厂模式可以结合简单工厂加反射写出更简洁、灵活的客户端代码，有兴趣的同学自己尝试一下。

Python的抽象工厂模式实现比C++版本简洁了不少，这得益于Python的鸭子类型。有关鸭子类型详见：《当DP遇见Py(五) — 工厂方法模式》。

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