c++ 门面模式(Facade)

门面模式是比较常用的一种设计模式，我们可能在无意中就会使用，门面模式就是用一个门面类来处理子系统的复杂关系，门面类简单的Api接口供客户端调用。用一个简单的演播室来表示。

#include <iostream>
using namespace std;

//class Camera;
//class Light;
//class Screen;
class Camera
{
public:
    Camera()
    {
    
    }
    ~Camera()
    {
    
    }
    void TrunOn()
    {
        cout << "摄像机打开!" << endl;
    }
    void TrunOff()
    {
        cout << "摄像机关闭!" << endl;
    }
    void Rotate(int degrees)
    {
        cout << "Rotate the camera by "<<degrees<< "degrees!" <<endl;
    }
};

class Light
{
public:
    Light()
    {
    
    }
    ~Light()
    {
    
    }
    void TrunOn()
    {
        cout << "灯光打开!" << endl;
    }
    void TrunOff()
    {
        cout << "灯光关闭!" << endl;
    }
};

class Screen
{
public:
    Screen()
    {
    
    }
    ~Screen()
    {
    
    }
    void TrunOn()
    {
        cout << "显示器打开!" << endl;
    }
    void TrunOff()
    {
        cout << "显示器关闭!" << endl;
    }
};

class Facade
{
public:
    Facade()
    {
        m_camera = new Camera();
        m_lights = new Light();
        m_Screen = new Screen();
    }
    ~Facade()
    {
        delete m_camera;
        delete m_lights;
        delete m_Screen;
    }
    void Activate()
    {
        cout<< "激活设备开始直播!"<<endl;
        m_camera->TrunOn();
        m_camera->Rotate(90);
        m_lights->TrunOn();
        m_Screen->TrunOn();

    }
    void Deactivate()
    {
        cout << "关闭设备!" << endl;
        m_camera->TrunOff();
        m_camera->Rotate(0);
        m_lights->TrunOff();
        m_Screen->TrunOff();
    }

private:
    Camera *m_camera;
    Light *m_lights;
    Screen *m_Screen;
};

主函数：

int main()
{
    Facade * m_facade = new Facade();
    m_facade->Activate();
    std::cout <<  "直播中!" << std::endl;
    m_facade->Deactivate();
    getchar();
    return 0;
}

输出结果：

激活设备开始直播!
摄像机打开!
Rotate the camera by 90degrees!
灯光打开!
显示器打开!
直播中!
关闭设备!
摄像机关闭!
Rotate the camera by 0degrees!
灯光关闭!
显示器关闭!

如果不使用门面类的话，每一个客户端都要直接去调用设备，会客户端的代码很复杂。可读性差。