设计模式——策略模式（Strategy）

定义好各个阶段的工作，然后按流程去走。

举一个例子：

文件操作有：打开，处理，关闭。

文件操作流程：打开——>处理——>关闭

CFileContext：操作的控制控制类

#include "IStrategy.h"class CFileContext{public:CFileContext(IStrategy* strategy);~CFileContext(void);void Operate();private:IStrategy *mp_strategy;};

CFileContext::CFileContext(IStrategy *strategy){mp_strategy = strategy;}CFileContext::~CFileContext(void){delete mp_strategy;}void CFileContext::Operate(){mp_strategy->Operate();}

IStrategy：各个操作的接口

#pragma onceclass IStrategy{public:IStrategy(void);virtual ~IStrategy(void);virtual void Operate() = 0;};

#include "IStrategy.h"IStrategy::IStrategy(void){}IStrategy::~IStrategy(void){}

CDealFileOpen，CDealFileWork，CDealFileClose

是对IStrategy的实现，分别实现打开，处理，关闭操作。

#pragma once#include "IStrategy.h"class CDealFileOpen : public IStrategy{public:CDealFileOpen(void);~CDealFileOpen(void);void Operate();};

<pre name="code" class="cpp">#pragma once#include "IStrategy.h"class CDealFileWork: public IStrategy{public:CDealFileWork(void);~CDealFileWork(void);void Operate();};

#pragma once#include "IStrategy.h"class CDealFileClose: public IStrategy{public:CDealFileClose(void);~CDealFileClose(void);void Operate();};

#include "DealFileOpen.h"#include <iostream>using std::cout;using std::endl;CDealFileOpen::CDealFileOpen(void){}CDealFileOpen::~CDealFileOpen(void){}void CDealFileOpen::Operate(){cout<<" Open File.\n "<<endl;}

程序运行结果：

 Open File.

Start to Work.

Close File.