中介者模式（行为模式）

概念:
用一个中介对象来封装一系列的对象交互，中介者使用各对象不需要显示相互引用，从而降低耦合，而且可以独立地改变他们之间的交互。
适用于：用一个中介对象，封装一系列对象的交换，中介者是各个对象不需要显示的相互作用，从而实现了耦合松散，而且可以独立的改变他们之间的交换。
模式有点：
1.将系统按照功能分割成更小的对象，符合类的最小设计原则，
2，对关联对象的集中控制
结构图：

需求：
现有男孩和女孩，男孩通过中介者发送“I Love My Girl”，女孩收到后通过中介者回复“I Love You Too”
实现;

class Person;
class Mediator{
private:
    Person *pboy;
    Person *pgirl;
public:
void set(Person *pb, Person *pg){
this->pboy = pb;
this->pgirl = pg;
    }
void send(string msg, Person *t);
};
class Person{
protected:
    Mediator *mediator;
public:
void set(Mediator *m){
this->mediator = m;
    }
virtual void send(string msg) = 0;
virtual void receive(string msg)=0;
};
class Boy :public Person{
public:
void send(string msg){
        cout << "男孩发送：" << msg << endl;
        mediator->send(msg, this);
    }
virtual void receive(string msg){
        cout << "男孩收到：" << msg << endl;
    }
};
class Girl :public Person{
public:
void send(string msg){
        cout << "女孩发送：" << msg << endl;
        mediator->send(msg, this);
    }
virtual void receive(string msg){
        cout << "女孩收到：" << msg << endl;
    }
};
void Mediator::send(string msg, Person *t){
if (t != pboy){
        pboy->receive(msg);
    }
else{
        pgirl->receive(msg);
    }
}

客户端;

int main(void){
    Mediator *mediator = new Mediator();
    Boy *boy = new Boy();
    Girl *girl = new Girl();
    boy->set(mediator);
    girl->set(mediator);
    mediator->set(boy, girl);
    boy->send("I Love My Girl");
    girl->send("I Love You Too");
    system("pause");
return 0;
}

运行结果;