设计模式：mediator模式

目的：解决多组件之间的通信问题，使得组件之间的通信变得简单

核心：提供一个管理类，用来处理组件之间的通信，所有的组件只和管理类通信，组件彼此之间不在单独通信

例子：

class Mediator
{
public:
    virtual void Send(string &message, Person *person) = 0;
    virtual void SetRenter(Person *renter) = 0;
    virtual void SetLandlord(Person *landlord) = 0;
};

class Person
{
public:
    virtual void SetMediator(Mediator *mediator) = 0;
    virtual void SendMessage(string message) = 0;
    virtual void GetMessage(string message) = 0;
protected:
    Mediator *p_mediator;    
};

class Renter: public Person
{
public:
    void SetMediator(Mediator *mediator)
	{
		p_mediator = mediator;
	}
    void SendMessage(string message)
	{ 
		p_mediator->Send(message, this);
	}
    void GetMessage(string message)
	{
		cout << "租房者收到房东发来的消息："<< message << endl;
	}
};

class Landlord: public Person
{
public:
    void SetMediator(Mediator *mediator)
	{
		p_mediator = mediator;
	}
    void SendMessage(string message)
	{ 
		p_mediator->Send(message,this);
	}
    void GetMessage(string message)
	{
		cout << "房东收到租客发来的消息：" << message << endl;
	}
};

class HouseMediator: public Mediator
{
private:
    Person *p_renter;
    Person *p_landlord;
	
public:
    HouseMediator(): p_renter(NULL), p_landlord(NULL)
	{
	}
    void SetRenter(Person *renter)
	{
		p_renter = renter;
	}
    void SetLandlord(Person *landlord)
	{
		p_landlord = landlord;
	}
    void Send(string &message, Person *person) //消息的处理函数
    {
        if(person == p_renter)
            p_landlord->GetMessage(message);
        else
            p_renter->GetMessage(message);
    }
};

int main() 
{
	Renter* r = new Renter();
	Landlord* l = new Landlord();
	HouseMediator* hm = new HouseMediator();
	r->SetMediator(hm);
	l->SetMediator(hm);
	hm->SetRenter(r);
	hm->SetLandlord(l);
	
	r->SendMessage(string("东西坏了，房东快来修理!"));
	l->SendMessage(string("到时间了，该叫房租了!"));
	
	return 0;
}