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#ifndef __STRATEGY_H__
#define __STRATEGY_H__
//策略模式(Strategy):它定义了一系列的算法,并将每一个算法封装起来,而且使它们还可以相互替换。策略模式让算法的变化不会影响到使用算法的客户。
//策略模式是很简单的设计模式,就是面向对象编程中多态的完整体现。
//我们可以看到客户端在使用的时候,使用哪种策略是由客户端决定的。
//抽象算法接口
class iStrategy
{
public:
virtual void algorithm(int a, int b) = 0;
};
//策略A
class StrategyA : public iStrategy
{
public:
virtual void algorithm(int a, int b);
};
//策略B
class StrategyB : public iStrategy
{
public:
virtual void algorithm(int a, int b);
};
//策略C
class StrategyC : public iStrategy
{
public:
virtual void algorithm(int a, int b);
};
//上下文类,定义客户端使用的接口并维护一个具体策略的实例
class Context
{
public:
Context(iStrategy *sgy);
virtual ~Context();
void execute(int a, int b);
private:
iStrategy *m_sgy;
};
void TestStrategy();
#endif
#include <stdio.h>
#include "Strategy.h"
void StrategyA::algorithm(int a, int b)
{
printf("a + b = %d \n", a+b);
}
void StrategyB::algorithm(int a, int b)
{
printf("a - b = %d \n", a-b);
}
void StrategyC::algorithm(int a, int b)
{
printf("a * b = %d \n", a*b);
}
Context::Context(iStrategy *sgy)
{
m_sgy = sgy;
}
Context::~Context()
{
}
void Context::execute(int a, int b)
{
m_sgy->algorithm(a,b);
}
void TestStrategy()
{
iStrategy * sgy1 = new StrategyA();
Context *con1 = new Context(sgy1);
con1->execute(5,3);
iStrategy * sgy2 = new StrategyC();
Context * con2 = new Context(sgy2);
con2->execute(5,3);
}