中介者模式

抽象中介者（Mediator）：抽象中介者角色定义统一的接口，用于各同事角色之间的通信。

抽象同事类（Colleague ）：每一个同事角色都知道中介者角色，而且与其它的同事角色通信的时候，一定要通过中介者角色协作。每个同事类的行为分两种：一种是同事本身行为，比如改变对象本身的状态，处理自己的行为等，这种行为叫做自发行为，与其它同事类或者中介者没有任何依赖；第二种是必须依赖中介者才能完成的行为，叫做依赖方法。

具体中介者类（Concrete Mediator）：具体中介者角色通过协调各同事角色实现协作行为，因此它必须依赖于各个同事角色。

具体同事类（Concrete Colleague）：这里以ConcreteColleague1为例，ConcreteColleague2不再赘述。

代码：

#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;
    }
};


int 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();

    getchar();
    return 0;
}

输出：

pdate ConcreteColleague2 from ConcreteColleague1
update ConcreteColleague1 from ConcreteColleague2

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参考：

https://www.guyuehome.com/38376