策略模式（Strategy Pattern）

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flyfish

#include "stdafx.h"#include <iostream>#include <map>using namespace std;typedef enum StrategyType{    StrategyA,    StrategyB,    StrategyC}STRATEGYTYPE;class Strategy{public:    virtual void Interface() = 0;    virtual ~Strategy() = 0;};Strategy::~Strategy(){}class ConcreteStrategyA : public Strategy{public:    void Interface()    {        cout << "ConcreteStrategyA." << endl;    }    ~ConcreteStrategyA() {}};class ConcreteStrategyB : public Strategy{public:    void Interface()    {        cout << "ConcreteStrategyB." << endl;    }    ~ConcreteStrategyB() {}};class ConcreteStrategyC : public Strategy{public:    void Interface()    {        cout << "ConcreteStrategyC." << endl;    }    ~ConcreteStrategyC() {}};class Context{    typedef void (Context::*pFun)();public:    void Interface(int type)    {        auto it = m_pMessageMap.find(type);        if (it != m_pMessageMap.end())        {            (this->*(it->second))();        }    };private:    std::map<int, pFun>   m_pMessageMap{        std::make_pair(STRATEGYTYPE::StrategyA, &Context::InterfaceA),        std::make_pair(STRATEGYTYPE::StrategyB, &Context::InterfaceB),        std::make_pair(STRATEGYTYPE::StrategyC, &Context::InterfaceC)    };    void InterfaceA()    {        m_pStrategy = new ConcreteStrategyA;            m_pStrategy->Interface();    };    void InterfaceB()    {        m_pStrategy = new ConcreteStrategyB;        m_pStrategy->Interface();    };    void InterfaceC()    {        m_pStrategy = new ConcreteStrategyC;        m_pStrategy->Interface();    };private:    Strategy *m_pStrategy;};int main(){    Context* p = new Context();    p->Interface(STRATEGYTYPE::StrategyC);    if (p) delete p;    system("pause");}

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