中介者模式（Mediator）:用一个中介对象来封装一系列的对象交互。中介者使对象不需要显式地相互引用，从而使其耦合松散，而且可以独立地改变他们之间的交互。

下面是中介者模式的UML图：

下面是C++实现的代码：

/*
 * Copyright (c) 2017 initm.com All rights reserved.
 * 作者: Stupid
 * 描述: 中介者模式
 * 完成时间: 2017-12-10 15:15
*/

#include <QCoreApplication>
#include <iostream>
#include <string>
#include <cstdlib>

class Colleague;

class Mediator
{
public:
    virtual void Send(const std::string& message, Colleague* colleague) = 0;

};

class Colleague
{
protected:
    Mediator* mediator;

public:
    Colleague(Mediator* mediator): mediator(mediator){}

};

class ConcreteColleague1: public Colleague
{
public:
    ConcreteColleague1(Mediator* mediator): Colleague(mediator){}
    void Send(const std::string& message){
        mediator->Send(message, this);
    }
    void Notify(const std::string& message){
        std::cout << "同事1收到消息: " << message << std::endl;
    }

};

class ConcreteColleague2: public Colleague
{
public:
    ConcreteColleague2(Mediator* mediator): Colleague(mediator){}
    void Send(const std::string& message){
        mediator->Send(message, this);
    }
    void Notify(const std::string& message){
        std::cout << "同事2收到消息: " << message << std::endl;
    }

};

class ConcreteMediator: public Mediator
{
private:
    ConcreteColleague1* concreteColleague1;
    ConcreteColleague2* concreteColleague2;

public:
    void SetConcreteColleague1(ConcreteColleague1* concreteColleague1){
        this->concreteColleague1 = concreteColleague1;
    }
    void SetConcreteColleague2(ConcreteColleague2* concreteColleague2){
        this->concreteColleague2 = concreteColleague2;
    }
    void Send(const std::string& message, Colleague* colleague){
        if(dynamic_cast<Colleague*>(concreteColleague1) == colleague){
            concreteColleague1->Notify(message);
        }else if(dynamic_cast<Colleague*>(concreteColleague2) == colleague){
            concreteColleague2->Notify(message);
        }
    }

};

int main(int argc, char *argv[])
{
    system("chcp 65001");
    QCoreApplication a(argc, argv);

    ConcreteMediator* concreteMediator = new ConcreteMediator;
    ConcreteColleague1* concreteColleague1 = new ConcreteColleague1(concreteMediator);
    ConcreteColleague2* concreteColleague2 = new ConcreteColleague2(concreteMediator);
    concreteMediator->SetConcreteColleague1(concreteColleague1);
    concreteMediator->SetConcreteColleague2(concreteColleague2);
    concreteColleague1->Send("你好，小李");
    concreteColleague2->Send("你好，老王");

    return a.exec();
}