行为模式：Command模式

Command模式通过将请求封装到一个对象（command）中，并将请求的接受者存放到具体的ConcreteCommand类中（Receiver）中，从而实现调用操作的对象和操作的具体实现者的解耦。

场景应用：windows下的画图软件，画笔的undo/redo操作。

//Reciever.h
#ifndef _RECIEVER_H_
#define _RECIEVER_H_

class Reciever 
{ 
public: 
	Reciever();
	~Reciever();
	void Action();

protected:
private:
};

#endif //~_RECIEVER_H_

//Reciever.cpp
#include "Reciever.h"
#include <iostream>
Reciever::Reciever()
{
}

Reciever::~Reciever() 
{
}

void Reciever::Action() 
{ 
	std::cout<<"Reciever action......."<<std::endl;
}

//Command.h
#ifndef _COMMAND_H_ 
#define _COMMAND_H_
class Reciever;

class Command 
{ 
public: 
	virtual ~Command();
	virtual void Excute() = 0;

protected: 
	Command();

private:
	
};

class ConcreteCommand : public Command 
{ 
public:
	ConcreteCommand(Reciever* rev);
	~ConcreteCommand();
	void Excute();

protected:

private:
	Reciever* _rev;
};

#endif //~_COMMAND_H_

//Command.cpp
#include "Command.h"
#include "Reciever.h"
#include <iostream>
Command::Command() 
{
}

Command::~Command() 
{
}

void Command::Excute() 
{
}

ConcreteCommand::ConcreteCommand(Reciever* rev) 
{ 
	this->_rev = rev;
}

ConcreteCommand::~ConcreteCommand() 
{ 
	delete this->_rev; 
}

void ConcreteCommand::Excute() 
{ 
	_rev->Action();

	std::cout<<"ConcreteCommand..."<<std::endl; 
}

//Invoker.h
#ifndef _INVOKER_H_
#define _INVOKER_H_

class Command;

class Invoker 
{ 
public:
	Invoker(Command* cmd);
	~Invoker();
	void Invoke();

protected:

private: 
	Command* _cmd; 
};

#endif //~_INVOKER_H_

//Invoker.cpp
#include "Invoker.h"
#include "Command.h"
#include <iostream>

Invoker::Invoker(Command* cmd) 
{ 
	_cmd = cmd;
}

Invoker::~Invoker() 
{ 
	delete _cmd;
}

void Invoker::Invoke() 
{ 
	_cmd->Excute();
}

//main.cpp
#include "Command.h"
#include "Invoker.h" 
#include "Reciever.h"
#include <iostream> 

using namespace std;

int main(int argc,char* argv[]) 
{ 
	Reciever* rev = new Reciever();
	Command* cmd = new ConcreteCommand(rev);
	Invoker* inv = new Invoker(cmd);
	inv->Invoke();

	system("pause");
	return 0;
}