設計模式之命令模式

命令模式將一個請求封裝爲一個對象，從而使你可用不同的請求對客戶進行參數化，對請求排隊或記錄請求日誌，以及支持可撤銷的操作。
命令模式的UML圖如下所示：

代碼如下：

class Barbecuer
{
public:
    Barbecuer() {}
    ~Barbecuer() {}

    void BakeMutton()
    {
        printf("Barbecuer yang rou\n");
    }

    void BakeChickenWing()
    {
        printf("Barbecuer ji chi\n");
    }
};

class Command
{
protected:
    Barbecuer *m_pReceive;
public:
    Command(Barbecuer * __b ) : m_pReceive(__b)
    {

    }
    virtual ~Command() {}

    virtual void ExcuteCommand(){ }
    virtual std::string  CommandBehavior() 
    {
        return "";
    }
};

class BakeMuttonCommand : public Command
{
public:
    BakeMuttonCommand(Barbecuer * __b) : Command(__b)
    {

    }
    ~BakeMuttonCommand() {}

    virtual void ExcuteCommand() 
    {
        m_pReceive->BakeMutton();
    }

    virtual std::string  CommandBehavior()
    {
        return "BakeMuttonCommand";
    }
};

class BakeChickenWingCommand : public Command
{
public:
    BakeChickenWingCommand(Barbecuer * __b) : Command(__b)
    {

    }
    ~BakeChickenWingCommand() {}

    virtual void ExcuteCommand()
    {
        m_pReceive->BakeChickenWing();
    }

    virtual std::string  CommandBehavior()
    {
        return "BakeChickenWingCommand";
    }
};

string getTime()
 {
     time_t timep;
     time(&timep);
     char tmp[64];
     strftime(tmp, sizeof(tmp), "%Y-%m-%d %H:%M:%S", localtime(&timep));
     return tmp;
 }

class Waiter
{
private:
    list<Command*> m_coms;
public:

    Waiter() {}
    ~Waiter() 
    {
        for each (Command* pCom in m_coms)
        {
            if (pCom)
            {
                delete pCom;
                pCom = NULL ;
            }
        }
    }
    void SetOrder(Command* __c)
    {
        if (NULL == __c)
        {
            cout << "Have not something to eat" << endl;
        }
        else
        {
            m_coms.push_back(__c);
            cout << "Add order:" <<__c->CommandBehavior() << "  Current Time:" << getTime()<<endl;

        }
    }

    void CancelOrder(Command* __c)
    {
        m_coms.remove(__c);
        cout << "Cancel order:" << __c->CommandBehavior() << "  Current Time:" << getTime()<<endl;
    }

    void Notify()
    {
        for each (Command* pCom in m_coms)
        {
            pCom->ExcuteCommand();
        }
    }
};

//客戶端代碼
int _tmain(int argc, TCHAR* argv[])
{
    Barbecuer *__b = new Barbecuer() ;
    Command * pCom1 = new BakeMuttonCommand(__b);
    Command * pCom2 = new BakeMuttonCommand(__b);
    Command * pCom3 = new BakeChickenWingCommand(__b);

    Waiter *pWaiter = new Waiter();
    pWaiter->SetOrder(pCom1);
    pWaiter->SetOrder(pCom2);
    pWaiter->SetOrder(pCom3);
    pWaiter->SetOrder(NULL);

    pWaiter->Notify();

    cout << "=============" << endl;
    pWaiter->CancelOrder(pCom2);
    pWaiter->Notify();

    if (__b)
    {
        delete __b;
        __b = NULL;
    }

    if (pWaiter)
    {
        delete pWaiter;
        pWaiter = NULL;
    }
    return 0;
}

運行結果：