[设计模式]<8>. C++与中介者模式(mediator pattern)

意图：用一个中介者对象封装一系列的对象交互。中介者使各对象不需要显式的相互引用，从而减小耦合。

原文：默默的EEer

地址：http://www.cnblogs.com/hebaichuanyeah/p/6091506.html

实际就是指，利用一个中介者对象来连接两个对象的操作。例如需求是，A对象更新/改变了，B对象也跟着相应的更新/改变，不通过直接调用B对象

一个例子，详见注释

#include <iostream>

using namespace std;

class Colleague;

//定义一个中介者接口，包含对象改变所需调用函数。
class Mediator
{
public :
    virtual ~Mediator()
    {

    }
    virtual void changed(Colleague *)=0;

};

//定义"同事"类接口，初始化需要一个中介者对象，并通过该类更新另外一个"同事"
class Colleague
{
public :
    //初始化中介者类对象
    Colleague(Mediator * mediator)
    {
        this->mediator =mediator;
    }
    //更新另外一个类
    virtual void changed()
    {
        mediator->changed(this);
    }
private:
    Mediator *mediator;
};

//具体的同事类1
class ConcreteColleague1 :public Colleague
{
public:
    ConcreteColleague1(Mediator * mediator):Colleague(mediator)
    {
    }
    void update()
    {
        cout<<"update ConcreteColleague1 from ConcreteColleague2"<<endl;
    }
};
//具体的同事类2
class ConcreteColleague2 :public Colleague
{
public :
    ConcreteColleague2(Mediator * mediator):Colleague(mediator)
    {
    }
    void update()
    {
        cout<<"update ConcreteColleague2 from ConcreteColleague1"<<endl;
    }
};

//具体的中介者类，实现更新函数changed。
class ConcreteMediator :public Mediator
{
private:
    ConcreteColleague1 * colleague1;
    ConcreteColleague2 * colleague2;
public:
    void setColleague1(ConcreteColleague1 * colleague)
    {
        colleague1 = colleague;
    }
    void setColleague2(ConcreteColleague2 * colleague)
    {
        colleague2 = colleague;
    }
    ConcreteMediator()
    {
        //colleague1 = new ConcreteColleague1(this);

    }
    ~ConcreteMediator()
    {

    }
    virtual void changed(Colleague* colleague)
    {
        if(colleague == colleague1)
        {
            colleague2->update();
        }
        else if(colleague == colleague2)
        {
            colleague1->update();
        }
        else;
    }

};
main()
{
    ConcreteMediator concreteMediator;
    ConcreteColleague1  colleague1(&concreteMediator);
    ConcreteColleague2  colleague2(&concreteMediator);
    concreteMediator.setColleague1(&colleague1);
    concreteMediator.setColleague2(&colleague2);
    //"同事1"通过中介者更新"同事2"
    colleague1.changed();
    //"同事2"通过中介者更新"同事1"
    colleague2.changed();

}