Strategy模式C++实现

作用:
定义一系列的算法,把它们一个个封装起来, 并且使它们可相互替换.本模式使得算法可独立于使用它的客户而变化.

UML结构图:

 

实现:
1)Strategy.h

/**//********************************************************************
    created:    2006/08/06
    filename:     Strategy.h
    author:        李创
                http://www.cppblog.com/converse/

    purpose:    Strategy模式的演示代码
*********************************************************************/

#ifndef STRATEGY_H
#define STRATEGY_H

class Strategy;

class Context
{
public:
    Context(Strategy *pStrategy);
    ~Context();

    void ContextInterface();
private:
    Strategy* m_pStrategy;
};

class Strategy
{
public:
    virtual ~Strategy(){}

    virtual void AlgorithmInterface() = 0;
};

class ConcreateStrategyA
    : public Strategy
{
public:
    virtual ~ConcreateStrategyA(){}

    virtual void AlgorithmInterface();
};

#endif

2)Strategy.cpp

/**//********************************************************************
    created:    2006/08/06
    filename:     Strategy.cpp
    author:        李创
                http://www.cppblog.com/converse/

    purpose:    Strategy模式的演示代码
*********************************************************************/

#include <iostream>
#include "Strategy.h"

Context::Context(Strategy *pStrategy)
    : m_pStrategy(pStrategy)
{
}

Context::~Context()
{
    delete m_pStrategy;
    m_pStrategy = NULL;
}

void Context::ContextInterface()
{
    if (NULL != m_pStrategy)
    {
        m_pStrategy->AlgorithmInterface();
    }
}

void ConcreateStrategyA::AlgorithmInterface()
{
    std::cout << "AlgorithmInterface Implemented by ConcreateStrategyA\n";
}

3)Main.cpp

/**//********************************************************************
    created:    2006/08/06
    filename:     Main.cpp
    author:        李创
                http://www.cppblog.com/converse/

    purpose:    Strategy模式的测试代码
*********************************************************************/

#include "Strategy.h"

int main()
{
    Strategy* pStrategy = new ConcreateStrategyA();
    Context*  pContext  = new Context(pStrategy);

    pContext->ContextInterface();

    delete pContext;

    return 0;
}