[GoF设计模式]Adapter模式和Chain Of Responsibility模式的C++实现

【Adapter模式】

 Adapter适配器模式是为了解决这样的一个问题：我已经在应用程序中设计好了接口，但是这个接口和第三方提供的接口不一致，为了使得这些  接口不兼容的类可以在一起工作，Adapter模式将一个类的第三方的接口转化为应用程序需要调用的接口。

 Adapter模式的实现有两种途径，一种是利用类的继承，一种是利用类的组合(聚合)（直接调用）来实现。即“接口继承”和“实现继承"的区别，  接口继承是指通过子类获得了父类的接口，而实现继承是指通过继承，子类获得父类的实现。C++中public继承即是接口继承和实现继承，既  继承了父类的接口又获得了父类的实现。一般来说通过private继承只获得实现继承，而接口的继承在C++中是通过在基类中的纯虚函数  virtual、=0来实现的。

【图解】

 以笔记本电脑只能插USB鼠标为例，现有一个PS接口的鼠标，需要用一个PS/USB的Adapter来转换。

 

【程序】

/******************************************************************* * * DESCRIPTION: Notebook's USB Mouse Service(Abstract Class) * [笔记本只能提供外置的USB接口的鼠标服务] * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ #ifndef USBMOUSESERVICE_H_ #define USBMOUSESERVICE_H_ class UsbMouseService { public: UsbMouseService(){} virtual ~UsbMouseService(){} /*Interface Functions*/ virtual void ProvideUsbService()=0; }; #endif  

/******************************************************************* * * DESCRIPTION: PsToUsbAdpater Class[Adapter] * 将Ps转化成Usb接口的适配器 * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ #ifndef PSTOUSBADAPTER_H_ #define PSTOUSBADAPTER_H_ /** include files **/ #include <iostream> #include "PsMouse.h" #include "UsbMouseService.h" using namespace std; /** * 通过继承的方式使用Adaptee即PsMouse: 插上PsMouse以后的适配器 * * @author roy nee (2009-9-24) */ class PsToUsbClassAdapter:public UsbMouseService,private PsMouse /*private is enough for adpatee*/ { public: PsToUsbClassAdapter(){} virtual ~PsToUsbClassAdapter(){} /*Interface Implement*/ virtual void ProvideUsbService() { cout<<"PsToUsbClassAdapter|-->Now UsbMouse Service is being called......"<<endl; this->UseMouse(); return; } }; /** * 通过组合(聚合)的方式使用Adaptee即PsMouse： 插上PsMouse以后的适配器 * * @author roy nee (2009-9-24) */ class PsToUsbObjectAdapter:public UsbMouseService { public: PsToUsbObjectAdapter(PsMouse *psmouse) { this->_psmouse=psmouse; } virtual ~PsToUsbObjectAdapter(){} /*Interface Implement*/ virtual void ProvideUsbService() { cout<<"PsToUsbObjectAdapter|-->Now UsbMouse Service is being called......"<<endl; this->_psmouse->UseMouse(); return; } private: PsMouse *_psmouse; }; #endif  

/******************************************************************* * * DESCRIPTION:PS Interface Mouse (Concreate Class) * * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ #ifndef PSMOUSE_H_ #define PSMOUSE_H_ /** include files **/ #include <iostream> using namespace std; class PsMouse { public: PsMouse(){} virtual ~PsMouse(){} /*functions*/ virtual void UseMouse() { cout<<"PsMouse: I am being used!/n"<<endl; return; } }; #endif  

/******************************************************************* * * DESCRIPTION: Adapter Pattern[适配器模式] * 以PS口鼠标在只有USB口的笔记本上的使用， * 利用PS/Usb转化适配器为例子 * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ /** include files **/ #include <iostream> #include "PsMouse.h" #include "UsbMouseService.h" #include "PsToUsbAdapter.h" /*Two Class in it*/ using namespace std; int main (int argc, char *argv[]) { cout<<"/n~~~~Class Sytle Adapter......"<<endl; /*Use Class Pattern Adapter*/ UsbMouseService *usbmouseservice=new PsToUsbClassAdapter(); usbmouseservice->ProvideUsbService(); cout<<"/n~~~~Object Sytle Adapter......"<<endl; /*User Object Pattern Adapter*/ PsMouse *psmouse=new PsMouse(); usbmouseservice=new PsToUsbObjectAdapter(psmouse); usbmouseservice->ProvideUsbService(); return(0); }  

【输出】

 

【Chain Of Responsibility模式】

Chain Of Responsibility模式是为了将可能处理一个请求的对象链接成一个对象的链条，并将请求在这个链条上传递，知道有对象处理该请求。（可能需要提供一个默认出苦力所有请求的类，最后）。该模式最大的好处就是给系统降低耦合性，请求的发送者完全不知道该请求会被哪个对象处理，极大的降低了系统的耦合性。

【图解】

以医院系统为例，县级医院治不了的病，自动转院到市级医院，市级医院仍然解决不了的疑难杂症自动转到省级医院治疗。

一个病人到县级医院去看病的情况，而他的病情是疑难杂症，从县级医院转到市级医院最后转到了省级医院。县级医院的上级医院是市级医院，而市级医院的上级是省级医院。病人不必关心该县级医院是否能治，不能治的话直接有该医院转到挂靠的上级市医院。

【程序】

/******************************************************************* * * DESCRIPTION:Hospital Handler Class[医院抽象类] * * AUTHOR:Neesky,相当于是一个抽象的链表结点类 * * DATE:2009-9-24 * *******************************************************************/ #ifndef HOSPITALHANDLER_H_ #define HOSPITALHANDLER_H_ /*include files*/ #include <iostream> using namespace std; /** * 疾病等级 */ enum SickGrade { LITTLESICK=0, /*常见的病*/ MIDDLESICK=1, /*中等难度的病*/ BADSICK=2 /*疑难杂症*/ }; class HospitalHandler { public: /*constructor and destructor*/ HospitalHandler(HospitalHandler *higherhospital=NULL) { this->_higherhospital=higherhospital; } virtual ~HospitalHandler(){} /*concrete function*/ virtual void SetHigherHospital(HospitalHandler *higherhospital) { this->_higherhospital=higherhospital; return; } virtual HospitalHandler* GetHigherHospital() { return this->_higherhospital; } virtual void CurePatient(SickGrade sickgrade)=0; protected:/*Important*/ HospitalHandler *_higherhospital;/*上一级医院*/ }; #endif  

/******************************************************************* * * DESCRIPTION:County Hospital [县级医院,能处理常见病]--Concrete Handler * * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ #ifndef COUNTYHOSPITAL_H_ #define COUNTYHOSPITAL_H_ /** include files **/ #include "HospitalHandler.h" class CountyHospital:public HospitalHandler { public: /*constructor and destructor*/ CountyHospital(HospitalHandler *higherhospital):HospitalHandler(higherhospital) { } virtual ~CountyHospital(){} /*concrete functions*/ virtual void CurePatient(SickGrade sickgrade) { if(sickgrade!=LITTLESICK) { cout<<"/nCountyHospital|--->:OH! The patient's ill seems serious, we can not cure it![*He must be sent to higher hospital!*]"<<endl; this->_higherhospital->CurePatient(sickgrade); } else cout<<"/nCountyHospital|--->:OH! Here is a patient with little sick, we can cure it!"<<endl; return; } }; #endif  

/******************************************************************* * * DESCRIPTION: City Hospital Class[市一级的医院] * * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ #ifndef CITYHOSPITAL_H_ #define CITYHOSPITAL_H_ /** include files **/ class CityHospital:public HospitalHandler { public: CityHospital(HospitalHandler *higherhospital):HospitalHandler(higherhospital) { } virtual ~CityHospital(){} /*concrete functions*/ virtual void CurePatient(SickGrade sickgrade) { if(sickgrade!=MIDDLESICK) { cout<<"/nCityHospital|--->:OH! The patient's ill seems serious, we can not cure it![*He must be sent to higher hospital!*]"<<endl; this->_higherhospital->CurePatient(sickgrade); } else cout<<"/nCityHospital|--->:OH! Here is a patient with middle sick, we can cure it!"<<endl; return; } }; #endif  

/******************************************************************* * * DESCRIPTION: Province Hospital Class[省级的医院] * * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ #ifndef PROVINCEHOSPITAL_H_ #define PROVINCEHOSPITAL_H_ /** include files **/ class ProvinceHospital:public HospitalHandler { public: ProvinceHospital(){} virtual ~ProvinceHospital(){} /*concrete functions*/ virtual void CurePatient(SickGrade sickgrade) { if(sickgrade==BADSICK) cout<<"/nProvinceHospital|--->:OH! Here is a patient with serious sick, we can cure it!"<<endl; return; } }; #endif  

/******************************************************************* * * DESCRIPTION: ChainOfResponsibility Pattern[责任链模式] * [县级医院->市级医院->省级医院] * AUTHOR:Neesky * * DATE:2009-9-24 * *******************************************************************/ /** include files **/ #include <iostream> #include "HospitalHandler.h" #include "CountyHospital.h" #include "CityHospital.h" #include "ProvinceHospital.h" using namespace std; int main (int argc, char *argv[]) { /*Now New 3 Hospitals*/ HospitalHandler *provincehospital=new ProvinceHospital(); HospitalHandler *cityhospital=new CityHospital(provincehospital); HospitalHandler *countyhospital=new CountyHospital(cityhospital); /*Here comes a patient in countyhospital,his illness is BadIllness*/ countyhospital->CurePatient(BADSICK); return(0); }  

【输出】