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 once

class 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.