抽象工厂模式程序示例—C++

我就是我 2022-05-30 00:54 116阅读 0赞

抽象工厂-提供一个接口，用于创建相关或从属对象的family，而不指定具体的类。  
抽象工厂模式允许类推迟实例化到子类。

如果我们想创建一个Mac风格的滚动条，我们可以写这样的代码：

ScrollBar *sb = new MacScrollBar;

但是，如果我们要使它在任何平台上工作，我们应该编写一个类似于此的代码：

ScrollBar *sb = guiFactory->createScrollBar();

因为guifactory是macfactory类的一个实例，该createscrollbar返回Mac风格的滚动条的一个新实例。  
macFactory本身是一个GUIFactory的抽象类，子类组件的通用接口。  
所以，这里的工厂产品对象是widgets(Button scrollBar等)。

实例变量guifactory初始化为：

GUIFactory *guiFactory = new MacFactory;

程序示例：

#include <iostream>
    using namespace std;
    
    // Button class
    class Button
    {
    public:
        virtual void paint() = 0;
    };
    
    // WindowsButton
    class WindowsButton : public Button
    {
    public:
        void paint()
        {
            cout << "Windows Button" << endl;
        }
    };
    
    // MacButton
    class MacButton : public Button
    {
    public:
        void paint()
        {
            cout << "Mac Button" << endl;
        }
    };
    
    
    // ScrollBar
    class ScrollBar
    {
    public:
        virtual void paint() = 0;
    };
    
    // Windows ScrollBar
    class WindowsScrollBar : public ScrollBar
    {
    public:
        void paint()
        {
            std::cout << "Windows ScrollBar \n";
        }
    };
    
    // Mac ScrollBar
    class MacScrollBar : public ScrollBar 
    {
    public:
        void paint()
        {
            std::cout << "Mac ScrollBar \n";
        }
    };
    
    
    // GUIFactory
    class GUIFactory
    {
    public:
        virtual Button* createButton() = 0;
        virtual ScrollBar* createScrollBar() = 0;
    };
    
    
    // WindowsFactory
    class WindowsFactory : public GUIFactory
    {
    public:
        Button* createButton()
        {
            return new WindowsButton;
        };
    
        ScrollBar* createScrollBar()
        {
            return new WindowsScrollBar;
        }
    };
    
    // MacFactory
    class MacFactory : public GUIFactory
    {
    public:
        Button* createButton()
        {
            return new MacButton;
        };
    
        ScrollBar* createScrollBar()
        {
            return new MacScrollBar;
        }
    };
    
    int main(int argc, char* argv[])
    {
        GUIFactory* guiFactory;
        Button* button;
        ScrollBar* scrollBar;
    
        // windows
        guiFactory = new WindowsFactory;
        button = guiFactory->createButton();
        button->paint();
        scrollBar = guiFactory->createScrollBar();
        scrollBar->paint();
    
        // mac
        guiFactory = new MacFactory;
        button = guiFactory->createButton();
        button->paint();
        scrollBar = guiFactory->createScrollBar();
        scrollBar->paint();
    
        getchar();
        return 0;
    }
    
    /*
    Windows Button
    Windows ScrollBar
    Mac Button
    Mac ScrollBar
    */

--------------------

/* 
    如果我们想添加iPhone风格的窗口样式，我们需要添加什么代码呢？
    // IPhoneButton
    class IPhoneButton : public Button
    {
    public:
        void paint()
        {
            cout << "iPhone Button" << endl;
        }
    };
    
    // iPhone ScrollBar
    class IPhoneScrollBar : public ScrollBar
    {
    public:
        void paint()
        {
            std::cout << "iPhone ScrollBar \n";
        }
    };
    
    // iPhoneFactory
    class IPhoneFactory : public GUIFactory
    {
    public:
        Button* createButton()
        {
            return new IPhoneButton;
        };
    
        ScrollBar* createScrollBar()
        {
            return new IPhoneScrollBar;
        }
    };
    
    main函数里面添加：
    // iphone
    guiFactory = new IPhoneFactory;
    button = guiFactory->createButton();
    button->paint();
    scrollBar = guiFactory->createScrollBar();
    scrollBar->paint();
    */

--------------------

原文地址：  
[http://www.bogotobogo.com/DesignPatterns/abstractfactorymethod.php][http_www.bogotobogo.com_DesignPatterns_abstractfactorymethod.php]

[http_www.bogotobogo.com_DesignPatterns_abstractfactorymethod.php]: http://www.bogotobogo.com/DesignPatterns/abstractfactorymethod.php