命令模式 Command

1. Client创建一个ConcreteCommand对象并指定他的Receiver对象

2. 某个Invoker对象存储该ConcreteCommand对象

3. 该Invoker通过调用Command对象的Execute操作来提交一个请求。若该命令是可撤销的，ConcreteCommand就在执行Execute操作之前存储当前状态以用于取消该命令

4. ConcreteCommand对象对调用它的Receiver的一些操作以执行该请求

 

// Command.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <list>
#include <iostream>
using namespace std;

class Barbecur{
public:
    void bakefish(){
        cout<<"开始烤鱼"<<endl;
    }
    void bakemeat(){
        cout<<"开始烤肉"<<endl;
    }
};
class Command{
public:
    Command(Barbecur * p){
        m_p = p;
    }
    virtual void execcommand() = 0;
    virtual ~Command(){}
protected:
    Barbecur * m_p;
};

class BakeFishCommand:public Command{
public:
    BakeFishCommand(Barbecur * p):Command(p){}
    void execcommand(){
        this->m_p->bakefish();
    }
};

class BakeMeatCommand:public Command{
public:
    BakeMeatCommand(Barbecur *p):Command(p){}
    void execcommand(){
        this->m_p->bakemeat();
    }
};

class Waiter{
public:
    void addcommand(Command * p ){
        m_list.push_back(p);
    }

    void cancelcommand(Command * p){
        m_list.remove(p);
    }

    void notify(){
        list<Command * >::iterator it;
        for(it = m_list.begin();it!=m_list.end();it++){
            (*it)->execcommand();
        }
    }
private:
    list<Command *> m_list;
};
int main(int argc, char* argv[])
{
    Barbecur * cooker = new Barbecur;
    Command * pfish = new BakeFishCommand(cooker);
    Command * pmeat = new BakeMeatCommand(cooker);

    Waiter * pwaiter = new Waiter;
    pwaiter->addcommand(pfish);
    pwaiter->addcommand(pmeat);
    pwaiter->notify();

    pwaiter->cancelcommand(pfish);
    pwaiter->notify();

    delete cooker;
    delete pfish;
    delete pmeat;
    delete pwaiter;
    return 0;
}