[结构型模式] head first 设计模式之外观模式(Facade)

╰+攻爆jí腚メ 2022-04-11 05:28 185阅读 0赞

1 目的  
\[color=red\]为子系统中的一组接口提供一个一致的界面，Facade模式定义了一个高层接口，这个接口使得这一子系统更加容易使用。外观模式的意图是简化接口。\[/color\]  
  
2 优点  
\[color=red\]a) 它对客户屏蔽子系统组件，因而减少了客户处理对的数目并使得子系统使用起来更加方便。  
b) 它实现了子系统与客户之间的松耦合关系，而子系统内部的功能组件往往是紧耦合的。  
c) 如果应用需要，它并不现在它们使用子系统类，因此你可以在系统易用性和通用性之间加以选择。\[/color\]  
  
\[img\]http://t25-1.yunpan.360.cn/p/800-600.f3dfc11f1812c21b78494acdaf71ad4e95d6378b.661428.jpg?t=7f39af56fd4daeef611a2c8707d9ce5b&d=20130822\[/img\]

//Facade
    //
    class Amplifier;
    class Tuner;
    class DvdPlayer;
    class CdPlayer;
    class Projector;
    class TheaterLights;
    class Screen;
    class PopcornPopper;
    //
    class HomeThreaterFacade
    {
       
    public:
        HomeThreaterFacade(Amplifier* amplifier, Tuner* tuner,
        DvdPlayer* dvdPlayer, CdPlayer* cdPlayer, Projector* projector, 
        TheaterLights* theaterLights, Screen* screen, PopcornPopper* popcornPopper)
        {
       
            m_Amplifier = amplifier;
            m_Tuner = tuner;
            m_DvdPlayer = dvdPlayer;
            m_CdPlayer = cdPlayer;
            m_Projector = projector;
            m_TheaterLights = theaterLights;
            m_Screen = screen;
            m_PopcornPopper = popcornPopper;
        }
    
        void watchMovie(string movie)
        {
       
            cout << "Get ready to watch a movie..."  << endl;
    //         m_PopcornPopper->on();
    //         m_PopcornPopper->pop();
    //         m_TheaterLights->dim(10);
    //         m_Screen->down();
    //         m_Projector->on();
    //         m_Projector->wideScreenMode();
    //         m_Amplifier->on();
    //         m_Amplifier->setDvd(m_DvdPlayer);
    //         m_Amplifier->setSurroundSound();
    //         m_Amplifier->setVolume(5);
    //         m_DvdPlayer->on();
    //         m_DvdPlayer->play();
        }
    
        void endMovie(string movie)
        {
       
            cout << "Shtting movie theater down..."  << endl;
    
    //         m_PopcornPopper->off();
    //         m_TheaterLights->on();
    //         m_Screen->up();
    //         m_Projector->off();
    //         m_Amplifier->off();
    //         m_DvdPlayer->stop();
    //         m_DvdPlayer->eject();
    //         m_DvdPlayer->off();
    
        }
    private:
        Amplifier*     m_Amplifier;
        Tuner*         m_Tuner;
        DvdPlayer*     m_DvdPlayer;
        CdPlayer*      m_CdPlayer;
        Projector*     m_Projector;
        TheaterLights* m_TheaterLights;
        Screen*        m_Screen;
        PopcornPopper* m_PopcornPopper;
    };
    
    //
    class HomeThreaterTestDrive
    {
       
    public:
        void run()
        {
       
    //         HomeThreaterFacade* homeTheater = new HomeThreaterFacade();
    //         homeTheater->watchMovie("Raiders of the Lost Ark");
    //         homeTheater->endMovie();
        }
    };

标准示例

#include <iostream>
    using namespace std;
    
    class Subsystem1
    {
       
    public:
        Subsystem1(){}
        ~Subsystem1(){}
    
        void Operation()
        {
       
            cout<<"Subsystem1 operation."<<endl;
        }
    };
    
    class Subsystem2
    {
       
    public:
        Subsystem2(){}
        ~Subsystem2(){}
    
        void Operation()
        {
       
            cout<<"Subsystem2 operation."<<endl;
        }
    };
    
    class Facade
    {
       
    public:
        Facade()
        {
       
            this->_subs1 = new Subsystem1();
            this->_subs2 = new Subsystem2();
        }
    
        ~Facade()
        {
       
            delete _subs1;
            delete _subs2;
        }
    
        void OperationWrapper()
        {
       
            this->_subs1->Operation();
            this->_subs2->Operation();
        }
    
    private:
        Subsystem1 *_subs1;
        Subsystem2 *_subs2;
    };
    
    int main(int argc, char *argv[])
    {
       
    	Facade *f = new Facade();
    	f->OperationWrapper();
    
    	return 0;
    }