设计模式之类对象结构型 — BRIDGE (桥接)模式

意图

将抽象部分与他的实现部分分离，使他们都可以独立的变化

实现

参考我的这篇文章（点这里），之前已经总结过了，就不重复了。
注意：之前仅仅是对代码依赖性的考虑，这次是在之前的基础上增加了控制不同实现的效果

代码示例

注意:这是完整的示例代码 vs2013编译通过

//windows.h 文件#pragma once#include <iostream>using namespace std;//使用声明式   降低耦合class WindowsImp;class Windows{public:    Windows();    virtual ~Windows();    virtual void paint(){};    virtual void drawContents(){};protected:    WindowsImp *getWindowImp();private:    WindowsImp *m_imp;};class IcoWindows:public Windows{public:    IcoWindows();    ~IcoWindows();    virtual void paint();    virtual void drawContents();private:    //  };class ButtonWindows :public Windows{public:    ButtonWindows();    ~ButtonWindows();    virtual void paint();    virtual void drawContents();private:    //};//windows.cpp 文件#include "Windows.h"#include "WindowsImp.h"#include "WindowsFactory.h"Windows::Windows():m_imp(NULL){}Windows::~Windows(){}WindowsImp * Windows::getWindowImp(){    if (m_imp==NULL)    {        m_imp = WindowsFactory::Instance()->getMicWinImp();    }    return m_imp;}IcoWindows::IcoWindows(){}IcoWindows::~IcoWindows(){}void IcoWindows::paint(){    cout << "我是IcoWindows   paint()" << endl;    //继承至父类，获取WindowsImp的实例    this->getWindowImp()->deviceRect();    return;}void IcoWindows::drawContents(){    cout << "我是IcoWindows   drawContents()" << endl;    this->getWindowImp()->paintBitmap();    return;}ButtonWindows::ButtonWindows(){}ButtonWindows::~ButtonWindows(){}void ButtonWindows::paint(){    cout << "我是ButtonWindows   paint()" << endl;    this->getWindowImp()->deviceRect();    return;}void ButtonWindows::drawContents(){    cout << "我是ButtonWindows   drawContents()" << endl;    this->getWindowImp()->paintBitmap();    return;}----------//windowsImp.h 文件#pragma once#include <iostream>using namespace std;/*Windows 类的实现类 */class WindowsImp{public:    virtual ~WindowsImp();    virtual void paintBitmap() = 0;    virtual void deviceRect() = 0;protected:    WindowsImp();};//微软的版本  class MicrosoftWindowsImp:public WindowsImp{public:    MicrosoftWindowsImp();    ~MicrosoftWindowsImp();    virtual void paintBitmap();    virtual void deviceRect();private:};//苹果系统的版本  class AppleWindowsImp:public WindowsImp{public:    AppleWindowsImp();    ~AppleWindowsImp();    virtual void paintBitmap();    virtual void deviceRect();private:};//windowsImp.cpp 文件#include "WindowsImp.h"WindowsImp::WindowsImp(){}WindowsImp::~WindowsImp(){}MicrosoftWindowsImp::MicrosoftWindowsImp(){}MicrosoftWindowsImp::~MicrosoftWindowsImp(){}void MicrosoftWindowsImp::paintBitmap(){    cout << "微软windows系统的  paintBitmap()" << endl;    return;}void MicrosoftWindowsImp::deviceRect(){    cout << "微软windows系统的  deviceRect()" << endl;}AppleWindowsImp::AppleWindowsImp(){}AppleWindowsImp::~AppleWindowsImp(){}void AppleWindowsImp::paintBitmap(){    cout << "苹果Mac系统的  paintBitmap()" << endl;    return;}void AppleWindowsImp::deviceRect(){    cout << "苹果Mac系统的  deviceRect()" << endl;    return;}----------//WindowsFactory.h文件#pragma once#include <iostream>using namespace std;class WindowsImp;class MicrosoftWindowsImp;class AppleWindowsImp;class WindowsFactory{public:    WindowsFactory();    ~WindowsFactory();     //工厂方法     WindowsImp * getMicWinImp();   //创建微软windows版本的实例    WindowsImp * getAppMacImp();   //创建苹果Mac版本的实例      /* 这里使用了 两个方法  来区分不同的系统版本对应的实现代码 */    /* 也可以通过宏定义 使用一个工厂方法就可以 自动的对应实现的代码 */    /* 也可以在创建Windows类的具体类的实例是 通过传入参数，来控制版本，总之方法很多  */    //单例模式       static WindowsFactory * Instance();private:    static WindowsFactory *m_win;    MicrosoftWindowsImp * m_micWin;    AppleWindowsImp * m_appWin;};//WindowsFactory.cpp文件#include "WindowsFactory.h"#include "WindowsImp.h"WindowsFactory::WindowsFactory():m_micWin(NULL), m_appWin(NULL){}WindowsFactory::~WindowsFactory(){}WindowsImp * WindowsFactory::getMicWinImp(){    if (m_micWin==NULL)    {        m_micWin = new MicrosoftWindowsImp();    }    return m_micWin;}WindowsImp * WindowsFactory::getAppMacImp(){    if (m_appWin==NULL)    {        m_appWin = new AppleWindowsImp();    }    return m_appWin;}WindowsFactory * WindowsFactory::Instance(){    if (m_win == NULL)    {        m_win = new WindowsFactory();    }    return m_win;}WindowsFactory * WindowsFactory::m_win=NULL;----------//main.cpp文件#include "Windows.h"int main(){    IcoWindows ico;    ico.drawContents();    ico.paint();    cout << "\n------------------------\n" << endl;    ButtonWindows butt;    butt.drawContents();    butt.paint();    getchar();    return 0;}

---

代码解析

• windows类是 窗口控件的抽象类 IcoWindows 类和 ButtonWIndows 类是他的具体子类，代表两种不同的控件
• windowsImp 类是 windows类的实现类 他的两个子类分别对应两个不同的实现版本
  使用 windowsImpFactory 类的工厂方法来实例化 windowsImp 的子类
  -windows类中的getWindowImp()方法来返回WindowsImp的实例
  windowsImpFactory 类使用了 单例模式

---

文件依赖图

效果

• 分离了接口及其实现部分，降低编译的依赖性
• 提高了可扩充性
• 隐藏了实现细节

---

我的个人网站 http://www.breeziness.cn/
我的CSDN http://blog.csdn.net/qq_33775402

转载请注明出处 小风code www.breeziness.cn