设计模式-行为-状态

#pragma once

#ifndef STATE_H 

#define STATE_H 

class State; 

class Context 
{ 
public: 
	Context(State* pState); 
	~Context(); 
	void Request(); 
	void ChangeState(State *pState); 

private: 
	State *m_pState; 
}; 

class State 
{ 
public: 
	virtual ~State(){} 
	virtual void Handle(Context* pContext) = 0; 
}; 

class ConcreateStateA : public State 
{ 
public: 
	void Handle(Context* pContext); 
}; 

class ConcreateStateB : public State 
{ 
public: 
	void Handle(Context* pContext); 
}; 

#endif 

#include "StdAfx.h"
#include "state_impl.h"

#include  

Context::Context(State* pState) 
: m_pState(pState) 
{ 
} 

Context::~Context() 
{ 
	delete m_pState; 
	m_pState = NULL; 
} 

void Context::Request() 
{ 
	if (NULL != m_pState) 
	{ 
		m_pState->Handle(this); 
	}
} 

void Context::ChangeState(State *pState) 
{ 
	if (NULL != m_pState) 
	{ 
		delete m_pState; 
		m_pState = NULL; 
	} 
	m_pState = pState; 
} 

void ConcreateStateA::Handle(Context* pContext) 
{ 
	std::cout