策略模式

#ifndef STRATEGY_H

#define STRATEGY_H

#include <iostream>

class Strategy//策略基类

{

public:

Strategy();

virtual ~Strategy(){std::cout << "~~\n";}

virtual void fun() = 0;

};

#endif // STRATEGY_H 
#include "strategy.h"
Strategy::Strategy()
{
}
#ifndef STRATEGYA_H
#define STRATEGYA_H
#include "strategy.h"
class StrategyA : public Strategy
{
public:
StrategyA();
~StrategyA(){}
void fun();
};
#endif // STRATEGYA_H
#include "strategya.h"
StrategyA::StrategyA()
{
}
void StrategyA::fun()
{
std::cout << "策略A！走为上" <<'\n';
}
#ifndef STRATEGYB_H
#define STRATEGYB_H
#include "strategy.h"
class StrategyB : public Strategy
{
public:
StrategyB();
~StrategyB(){}
void fun();
};
#endif // STRATEGYB_H
#include "strategyb.h"
StrategyB::StrategyB()
{
}
void StrategyB::fun()
{
std::cout << "策略B！老婆天下第一，逛街去" <<'\n';
}
#ifndef STRATEGYC_H
#define STRATEGYC_H
#include "strategy.h"
class StrategyC : public Strategy
{
public:
StrategyC();
~StrategyC(){}
void fun();
};
#endif // STRATEGYC_H
#include "strategyc.h"
StrategyC::StrategyC()
{
}
void StrategyC::fun()
{
std::cout << "策略C！金蝉脱壳" <<'\n';
}
#ifndef CONTEXT_H
#define CONTEXT_H
#include "strategy.h"
class Context//应用的上下文类
{
public:
Context();
Context(Strategy *p);
~Context(){delete p_stratery;}
void setStratery(Strategy *p) {delete p_stratery;p_stratery = p;}
void useStratery() const {if(p_stratery != 0)p_stratery->fun();}
private:
Strategy *p_stratery;
};
#endif // CONTEXT_H
#include "context.h"
Context::Context():p_stratery(0)
{
}
Context::Context(Strategy *p):p_stratery(p)
{
}
#include <iostream>
using namespace std;
#include "context.h"
#include "strategya.h"
#include "strategyb.h"
#include "strategyc.h"
int main()
{
cout << "老班让加班！策略A..." << '\n';
Context me(new StrategyA);
me.useStratery();
cout << "老婆让逛街！策略B..." << '\n';
me.setStratery(new StrategyB);
me.useStratery();
cout << "兄弟叫喝酒！可老婆让早点回家！策略C..." << '\n';
me.setStratery(new StrategyC);
me.useStratery();
return 0;
}
最后来张运行图