設計模式之命令模式（Command）

     命令模式（Command）把請求封裝成一個對象，使請求能夠存儲更多的信息擁有更多的能力。命令模式同樣能夠把請求的發送者和接收者解耦，但它不關心請求將以何種方式被處理。命令模式經常與職責鏈模式（Chain of Responsibility）和組合模式（Composite）一起使用：職責鏈模式處理命令模式封裝的對象，組合模式可以把簡單的命令對象組合成復雜的命令對象。

      本文舉了一個在飯店點菜的例子。（1）烤肉師傅負責在後台（廚房）做飯。（2）Command負責提供提供各種命令，相當於菜單。（3）服務員與客服打交道，負責記錄客戶點了哪些菜（把客戶的命令記下來），然後交給廚師去做。（4）客戶就負責點菜。

代碼：

#include <iostream>   
#include <vector>   
#include <string>   
using namespace std;  
  
  
class Command;  
class MakeChikenCmd;  
class MakeMuttonCmd;  
//烤肉師傅   
class RoastCook{   
    friend class MakeChikenCmd;  
    friend class MakeMuttonCmd;  
private:  
    void MakeMutton()   
    { cout << "烤羊肉"; }  
    void MakeChickenWing()   
    { cout << "烤雞翅膀"; }  
};  
  
//命令的接口，抽象類   
class Command{  
public:  
    Command(RoastCook* cook)  
    {  
        cooker = cook;  
    }  
    virtual ~Command(){}  
    virtual void Execute()=0;  
protected:  
    RoastCook *cooker;//包含了烤肉師傅的對象   
};  
  
//烤羊肉命令   
class MakeMuttonCmd : public Command{  
public:  
    MakeMuttonCmd(RoastCook *cook):Command(cook){}  
    void Execute()  
    {  
        cooker->MakeMutton();  
    }  
};  
//烤雞肉命令   
class MakeChikenCmd : public Command{  
public:  
    MakeChikenCmd(RoastCook *cook):Command(cook){}  
    void Execute()  
    {  
        cooker->MakeChickenWing();  
    }  
};  
  
//服務員類，負責與客服交互   
class Waiter{  
public:  
    Waiter(string _name)  
    {this->name = _name;}  
    void AddOder(Command* subOder)//加入客戶點的菜   
    {  
        oder.push_back(subOder);  
    }  
  
    void Notify()  
    {  
        vector<Command*>::iterator iter;  
        cout<<name<<" 通知烤肉師傅請做:"<<endl;  
        for(iter = oder.begin();iter!=oder.end();++iter){  
            cout<<"                   ";  
            (*iter)->Execute();  
            cout<<endl;  
        }  
    }  
  
    string getName()const  
    {return name;}  
private:  
    vector<Command*> oder;//點菜單   
    string name;//服務員名字   
};  
  
class Custmer{  
public:  
    Custmer(string myname)  
    {  
        this->name = myname;  
        this->w = NULL;  
    }  
  
    void CustmerOder(Command *cmd)  
    {  
        cout<<"顧客"<<name<<"點菜"<<endl;  
        w->AddOder(cmd);  
    }  
  
    void CallWaiter(Waiter *_w)  
    {  
        cout<<"顧客"<<name<<"呼叫服務員"<<endl;  
        this->w = _w;  
        cout<<"服務員"<<w->getName()<<"為您服務"<<endl;  
    }  
private:  
    string name;  
    Waiter *w;  
};  
  
int main()  
{  
    RoastCook *cooker = new RoastCook();  
    Command *cmd = new MakeChikenCmd(cooker);  
    Command *cmd1 = new MakeMuttonCmd(cooker);  
  
    Waiter waiter("sps");  
    Custmer cust("lsj");  
    cust.CallWaiter(&waiter);//呼叫服務員   
  
    cust.CustmerOder(cmd);//點菜   
    cust.CustmerOder(cmd1);//點菜   
  
    waiter.Notify();//服務員通知後台   
  
    system("pause");  
    return 0;  
}  

#include <iostream>
#include <vector>
#include <string>
using namespace std;


class Command;
class MakeChikenCmd;
class MakeMuttonCmd;
//烤肉師傅
class RoastCook{ 
	friend class MakeChikenCmd;
	friend class MakeMuttonCmd;
private:
	void MakeMutton() 
	{ cout << "烤羊肉"; }
	void MakeChickenWing() 
	{ cout << "烤雞翅膀"; }
};

//命令的接口，抽象類
class Command{
public:
	Command(RoastCook* cook)
	{
		cooker = cook;
	}
    virtual ~Command(){}
	virtual void Execute()=0;
protected:
	RoastCook *cooker;//包含了烤肉師傅的對象
};

//烤羊肉命令
class MakeMuttonCmd : public Command{
public:
	MakeMuttonCmd(RoastCook *cook):Command(cook){}
	void Execute()
	{
		cooker->MakeMutton();
	}
};
//烤雞肉命令
class MakeChikenCmd : public Command{
public:
	MakeChikenCmd(RoastCook *cook):Command(cook){}
	void Execute()
	{
		cooker->MakeChickenWing();
	}
};

//服務員類，負責與客服交互
class Waiter{
public:
	Waiter(string _name)
	{this->name = _name;}
	void AddOder(Command* subOder)//加入客戶點的菜
	{
		oder.push_back(subOder);
	}

	void Notify()
	{
		vector<Command*>::iterator iter;
		cout<<name<<" 通知烤肉師傅請做:"<<endl;
		for(iter = oder.begin();iter!=oder.end();++iter){
			cout<<"                   ";
			(*iter)->Execute();
			cout<<endl;
		}
	}

	string getName()const
	{return name;}
private:
	vector<Command*> oder;//點菜單
	string name;//服務員名字
};

class Custmer{
public:
	Custmer(string myname)
	{
		this->name = myname;
		this->w = NULL;
	}

	void CustmerOder(Command *cmd)
	{
		cout<<"顧客"<<name<<"點菜"<<endl;
		w->AddOder(cmd);
	}

	void CallWaiter(Waiter *_w)
	{
	    cout<<"顧客"<<name<<"呼叫服務員"<<endl;
		this->w = _w;
		cout<<"服務員"<<w->getName()<<"為您服務"<<endl;
	}
private:
	string name;
	Waiter *w;
};

int main()
{
	RoastCook *cooker = new RoastCook();
	Command *cmd = new MakeChikenCmd(cooker);
	Command *cmd1 = new MakeMuttonCmd(cooker);

    Waiter waiter("sps");
	Custmer cust("lsj");
    cust.CallWaiter(&waiter);//呼叫服務員

	cust.CustmerOder(cmd);//點菜
	cust.CustmerOder(cmd1);//點菜

	waiter.Notify();//服務員通知後台

	system("pause");
	return 0;
}