设计模式之中介者模式(Mediator)

优点：允许我们公开一个统一的接口，系统的不同部分可以通过该接口进行通信，而不需要显示的相互作用；
适用场景：一个系统的各个组件之间看起来有太多的直接关系，这个时候则需要一个中心控制点，以便各个组件可以通过这个中心控制点进行通信；

#include 
#include 
using namespace std;

class Mediator;

class Person
{
public:
    virtual void setMediator(Mediator *mediator) = 0;
    virtual void sendMessage(string) = 0;
    virtual void getMessage(string) = 0;
protected:
    Mediator *_mediator;
};

class Mediator
{
public:
    virtual void send(string &, Person *person) = 0;
    virtual void setA(Person *) = 0;
    virtual void setB(Person *) = 0;
};

class Rental : public Person
{
public:
    void setMediator(Mediator *mediator)
    {
        _mediator = mediator;
    }

    void sendMessage(string data)
    {
        _mediator->send(data,this);
    }

    void getMessage(string data)
    {
        cout << "Rental get Message:" << data << endl;
    }
};

class Landlord : public Person
{
public:
    void setMediator(Mediator *mediator)
    {
        _mediator = mediator;
    }

    void sendMessage(string data)
    {
        _mediator->send(data,this);
    }

    void getMessage(string data)
    {
        cout << "Landlord get Message:" << data << endl;
    }
};

class HouseMediator : public Mediator
{
public:
    HouseMediator()
    {
        _personA = NULL;
        _personB = NULL;
    }

    void setA(Person *a)
    {
        _personA = a;
    }

    void setB(Person *b)
    {
        _personB = b;
    }

    void send(string &data, Person *person)
    {
        if(_personA == person)
            _personB->getMessage(data);
        else
            _personA->getMessage(data);
    }

private:
    Person *_personA;
    Person *_personB;
};

int main()
{
    Mediator *mediator = new HouseMediator;
    Person *person1 = new Rental;
    Person *person2 = new Landlord;
    mediator->setA(person1);
    mediator->setB(person2);
    person1->setMediator(mediator);
    person2->setMediator(mediator);

    person1->sendMessage("I want get house");
    person2->sendMessage("I want sell house");

    return 0;
}