设计模式学习——工厂模式（Factory Pattern）

1、有一个工厂，专门生产不同品牌的汽车。当有人需要从此工厂提货的时候，只需要告诉他，要什么品牌的，就可以了，并不关心这些车是怎么生产出来的。

2、以上方式，如果增加品牌的时候，也要修改工厂，有点麻烦。于是，把工厂也抽象了。

1的类图与实现：

首先，是通用的车

  ///
  /// @file    Car.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:10:31
  ///

 #ifndef __CAR_H__
 #define __CAR_H__

 #include <iostream>

 namespace marrs{

 using std::cout;
 using std::cerr;
 using std::endl;

 class Car
 {
     public:
         Car() : b_IsRunning(){}
         virtual ~Car(){};
     public:
         virtual void Run() = ;
         virtual void Stop() = ;
     protected:
         bool b_IsRunning;
 };

 }

 #endif //__CAR_H__

然后是不同品牌的车，继承自Car

  ///
  /// @file    Benz.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:20:54
  ///

 #ifndef __BENZ_H__
 #define __BENZ_H__

 #include "Car.h"

 namespace marrs{

 class Benz
 : public Car
 {
     public:
         ~Benz(){}
     public:
         void Run();
         void Stop();
 };

 }

 #endif //__BENZ_H__

  ///
  /// @file    Benz.cc
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:21:54
  ///

 #include "Benz.h"

 namespace marrs{

 void Benz::Run()
 {
     if (b_IsRunning)
     {
         cerr << "Benz is running!" << endl;
     }

     cout << "Benz is going to running!" << endl;
     b_IsRunning = true;
 }

 void Benz::Stop()
 {
     if (!b_IsRunning)
     {
         cerr << "Benz isn't running..." << endl;
     }

     cout << "Benz is going to stopping!" << endl;
     b_IsRunning = false;
 }

 }

  ///
  /// @file    Audi.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:20:54
  ///

 #ifndef __AUDI_H__
 #define __AUDI_H__

 #include "Car.h"

 namespace marrs{

 class Audi
 : public Car
 {
     public:
         ~Audi(){}
     public:
         void Run();
         void Stop();
 };

 }

 #endif//__AUDI_H__

  ///
  /// @file    Audi.cc
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:21:54
  ///

 #include "Audi.h"

 namespace marrs{

 void Audi::Run()
 {
     if (b_IsRunning)
     {
         cerr << "Audi is running!" << endl;
     }

     cout << "Audi is going to running!" << endl;
     b_IsRunning = true;
 }

 void Audi::Stop()
 {
     if (!b_IsRunning)
     {
         cerr << "Audi isn't running..." << endl;
     }

     cout << "Audi is going to stopping!" << endl;
     b_IsRunning = false;
 }

 }

  ///
  /// @file    Lamborghini.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:20:54
  ///

 #ifndef __LAMBORGHINI_H__
 #define __LAMBORGHINI_H__

 #include "Car.h"

 namespace marrs{

 class Lamborghini
 : public Car
 {
     public:
         ~Lamborghini(){}
     public:
         void Run();
         void Stop();
 };

 }

 #endif//__LAMBORGHINI_H__

  ///
  /// @file    Lamborghini.cc
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:21:54
  ///

 #include "Lamborghini.h"

 namespace marrs{

 void Lamborghini::Run()
 {
     if (b_IsRunning)
     {
         cerr << "Lamborghini is running!" << endl;
     }

     cout << "Lamborghini is going to running!" << endl;
     b_IsRunning = true;
 }

 void Lamborghini::Stop()
 {
     if (!b_IsRunning)
     {
         cerr << "Lamborghini isn't running..." << endl;
     }

     cout << "Lamborghini is going to stopping!" << endl;
     b_IsRunning = false;
 }

 }

接着，有个生产工厂

  ///
  /// @file    Factory.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:27:42
  ///

 #ifndef __FACTORY_H__
 #define __FACTORY_H__

 #include "Benz.h"
 #include "Audi.h"
 #include "Lamborghini.h"

 enum Brand
 {
     EN_BRAND_CAR_BANZ = ,
     EN_BRAND_CAR_AUDI,
     EN_BRAND_CAR_LAMBORGHINI,
 };

 namespace marrs{

 using std::cout;
 using std::endl;

 class Factory
 {
 public:
     Car * Produce(int int_brand);
     void Reclaim(Car * car_brand);
 };

 }

 #endif //__FACTORY_H__

  ///
  /// @file    Factory.cc
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:39:05
  ///

 #include "Factory.h" 

 namespace marrs{

 Car * Factory::Produce(int int_brand)
 {
     switch(int_brand)
     {
         case EN_BRAND_CAR_BANZ:
             return new Benz;
         case EN_BRAND_CAR_AUDI:
             return new Audi;
         case EN_BRAND_CAR_LAMBORGHINI:
             return new Lamborghini;
         default:break;
     }
     return NULL;
 }

 void Factory::Reclaim(Car * car_brand)
 {
     delete car_brand;
 }

 }

为了方便统一处理方式，我把车的销毁也放到工厂类里了。

  ///
  /// @file    main.cc
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:40:59
  ///

 #include "Factory.h"

 using namespace marrs;

 int main()
 {
     Factory factory;

     Car * car_first = factory.Produce(EN_BRAND_CAR_BANZ);
     car_first->Run();
     car_first->Stop();
     factory.Reclaim(car_first);

     Car * car_second = factory.Produce(EN_BRAND_CAR_AUDI);
     car_second->Run();
     car_second->Stop();
     factory.Reclaim(car_second);

     Car * car_third = factory.Produce(EN_BRAND_CAR_LAMBORGHINI);
     car_third->Run();
     car_third->Stop();
     factory.Reclaim(car_third);

 }

编译，运行

[ccx@ubuntu ~/object-oriented/Factory-Pattern]$>g++ * -o car_factory.exe
[ccx@ubuntu ~/object-oriented/Factory-Pattern]$>./car_factory.exe
Benz is going to running!
Benz is going to stopping!
Audi is going to running!
Audi is going to stopping!
Lamborghini is going to running!
Lamborghini is going to stopping!

2的类图与实现 （画图功底不行....略乱）

在1的基础之上，修改Factory

  ///
  /// @file    Factory.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:27:42
  ///

 #ifndef __FACTORY_H__
 #define __FACTORY_H__

 #include "Car.h"

 namespace marrs{

 using std::cout;
 using std::endl;

 class Factory
 {
     public:
         virtual ~Factory(){}
     public:
         virtual Car * Produce() = ;
         void Reclaim(Car * car_brand)
         {
             delete car_brand;
         }
 };

 }

 #endif //__FACTORY_H__

然后是不同的工厂

  ///
  /// @file    Benz_Factory.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 21:21:58
  ///

 #ifndef __BENZ_FACTORY_H__
 #define __BENZ_FACTORY_H__

 #include "Factory.h"
 #include "Benz.h"

 namespace marrs{

 class BenzFactory
 : public Factory
 {
     public:
         Car * Produce()
         {
             return new Benz;
         }
 };

 }

 #endif // __BENZ_FACTORY_H__

  ///
  /// @file    Audi_Factory.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 21:21:58
  ///

 #ifndef __AUDI_FACTORY_H__
 #define __AUDI_FACTORY_H__

 #include "Factory.h"
 #include "Audi.h"

 namespace marrs{

 class AudiFactory
 : public Factory
 {
     public:
         Car * Produce()
         {
             return new Audi;
         }
 };

 }

 #endif // __AUDI_FACTORY_H__

  ///
  /// @file    Lamborghini_Factory.h
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 21:21:58
  ///

 #ifndef __LAMBORGHINI_FACTORY_H__
 #define __LAMBORGHINI_FACTORY_H__

 #include "Factory.h"
 #include "Lamborghini.h"

 namespace marrs{

 class LamborghiniFactory
 : public Factory
 {
     public:
         Car * Produce()
         {
             return new Lamborghini;
         }
 };

 }

 #endif // __LAMBORGHINI_FACTORY_H__

最后修改main.cc

  ///
  /// @file    main.cc
  /// @author  marrs(chenchengxi993@gmail.com)
  /// @date    2017-08-12 20:40:59
  ///

 #include "Benz_Factory.h"
 #include "Audi_Factory.h"
 #include "Lamborghini_Factory.h"

 using namespace marrs;

 void BenzAction()
 {
     Factory * factory = new BenzFactory;
     Car * car_first = factory->Produce();
     car_first->Run();
     car_first->Stop();
     factory->Reclaim(car_first);
     delete factory;
 }

 void AudiAction()
 {
     Factory * factory = new AudiFactory;
     Car * car_first = factory->Produce();
     car_first->Run();
     car_first->Stop();
     factory->Reclaim(car_first);
     delete factory;
 }

 void LamborghiniAction()
 {
     Factory * factory = new LamborghiniFactory;
     Car * car_first = factory->Produce();
     car_first->Run();
     car_first->Stop();
     factory->Reclaim(car_first);
     delete factory;
 }

 int main()
 {
     BenzAction();
     AudiAction();
     LamborghiniAction();

     return ;
 }

编译，运行

[ccx@ubuntu ~/object-oriented/Factory-Pattern_2]$>g++ * -o car_Factory.exe
[ccx@ubuntu ~/object-oriented/Factory-Pattern_2]$>./car_Factory.exe
Benz is going to running!
Benz is going to stopping!
Audi is going to running!
Audi is going to stopping!
Lamborghini is going to running!
Lamborghini is going to stopping!