Strategy模式C++实现

说明：将《Head First设计模式》中策略模式，用C++来实现。

飞翔行为FlyBehavior.h：

#pragma once

#include <iostream>

using namespace std;

class IFlyBehavior

{

public:

virtual ~IFlyBehavior(){}

virtual void Fly() = 0;

};

class CFlyWithWings : public IFlyBehavior

{

public:

void Fly()

{

cout<<"I'm flying"<<endl;

}

};

class CFlyNoWay : public IFlyBehavior

{

public:

void Fly()

{

cout<<"I can't fly"<<endl;

}

};

class CFlyRocketPowered : public IFlyBehavior

{

public:

void Fly()

{

cout<<"I'm flying with a rocket!"<<endl;

}

};

鸣叫行为QuackBehavior.h：

#pragma once

#include <iostream>

using namespace std;

class IQuackBehavior

{

public:

virtual ~IQuackBehavior(){}

virtual void Quack() = 0;

};

class CQuack : public IQuackBehavior

{

public:

void Quack()

{

cout<<"Quack"<<endl;

}

};

class CMuteQuack : public IQuackBehavior

{

public:

void Quack()

{

cout<<"Silence"<<endl;

}

};

class CSqueak : public IQuackBehavior

{

public:

void Quack()

{

cout<<"Squeak"<<endl;

}

};

鸭子类：

#pragma once

#include "FlyBehavior.h"

#include "QuackBehavior.h"

class CDuck

{

public:

CDuck()

: m_pFly(NULL)

, m_pQuack(NULL)

{

}

virtual ~CDuck(){}

virtual void Display() = 0;

void SetFlyBehavior(IFlyBehavior* pFly)

{

m_pFly = pFly;

}

void SetQuackBehavior(IQuackBehavior* pQuack)

{

m_pQuack = pQuack;

}

void PerformFly()

{

if (NULL == m_pFly)

{

return;

}

m_pFly->Fly();

}

void PerformQuack()

{

if (NULL == m_pQuack)

{

return;

}

m_pQuack->Quack();

}

protected:

IFlyBehavior* m_pFly;

IQuackBehavior* m_pQuack;

};

class CMallardDuck : public CDuck

{

public:

CMallardDuck()

{

m_pFly = new CFlyWithWings();

m_pQuack = new CQuack();

}

void Display()

{

cout<<"I'm a real Mallard duck"<<endl;

}

};

class CModelDuck : public CDuck

{

public:

CModelDuck()

{

m_pFly = new CFlyNoWay();

m_pQuack = new CQuack();

}

void Display()

{

cout<<"I'm a model duck"<<endl;

}

};

调用方法：

int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])

{

int nRetCode = 0;

// initialize MFC and print and error on failure

if (!AfxWinInit(::GetModuleHandle(NULL), NULL, ::GetCommandLine(), 0))

{

// TODO: change error code to suit your needs

_tprintf(_T("Fatal Error: MFC initialization failed\n"));

return 1;

}

CDuck* pMallard = new CMallardDuck();

pMallard->PerformQuack();

pMallard->PerformFly();

delete pMallard;

pMallard = NULL;

CDuck* pModel = new CModelDuck();

pModel->PerformFly();

pModel->SetFlyBehavior(new CFlyRocketPowered());

pModel->PerformFly();

delete pModel;

pModel = NULL;

return nRetCode;

}