设计模式之中介者模式

中介者模式用一个中介对象封装一系列的对象交互。中介者使各对象不需要显式地相互引用，从而使其耦合松散,而且可独立改变它们之间的交互。

如果具体中介者维护的具体的对象繁多时，维护可能比较麻烦。
代码如下：

class Colleague
{
protected:
    Mediator *m_pMediator;
public:
    Colleague( Mediator* __m )
    {
        if ( __m != NULL )
        {
            m_pMediator = __m;
        }
    }
    ~Colleague(){}
};
class ColleagueOne : public Colleague
{
public:
    ColleagueOne( Mediator* __m):Colleague( __m ){}
    ~ColleagueOne(){}

    void Send( string& strMessage )
    {
        m_pMediator->Send(strMessage,this);
    }

    void Notify( string& strMessage )
    {
        printf("ColleagueOne get information:%s\n", strMessage.c_str() );
    }
};
class ColleagueTwo : public Colleague
{
public:
    ColleagueTwo( Mediator* __m):Colleague( __m ){}
    ~ColleagueTwo(){}

    void Send( string& strMessage )
    {
        m_pMediator->Send(strMessage,this);
    }

    void Notify( string& strMessage )
    {
        printf("ColleagueTwo get information:%s\n", strMessage.c_str() );
    }
};

class Mediator
{
public:
    virtual void Send( string &message, Colleague * pCol ){};
};
class ConcreteMediator: public Mediator
{
private:
    ColleagueOne * m_pColOne;
    ColleagueTwo * m_pColTwo;
public:
    void SetColleagueOne(ColleagueOne* pColOne)
    {
        if ( pColOne != NULL )
        {
            m_pColOne = pColOne ;
        }
    }

    void SetColleagueTwo(ColleagueTwo* pColTwo)
    {
        if ( pColTwo != NULL )
        {
            m_pColTwo = pColTwo ;
        }
    }

    virtual void Send( string &message, Colleague * pCol )
    {
        if ( pCol == m_pColOne )
        {
            m_pColTwo->Notify( message );
        } 
        else
        {
            m_pColOne->Notify( message );
        }
    }
};

//客户端代码
int main(   )
{
    ConcreteMediator *pMediator = new ConcreteMediator();

    ColleagueOne* pColOne = new ColleagueOne( pMediator );
    ColleagueTwo* pColTwo = new ColleagueTwo( pMediator );

    pMediator->SetColleagueOne(pColOne );
    pMediator->SetColleagueTwo(pColTwo );

    pColOne->Send(string("Have lunch?"));
    pColTwo->Send(string("Not yet. Is it your pleaure?") );

    if ( pMediator )
    {
        delete pMediator ;
        pMediator = NULL ;
    }

    if ( pColOne )
    {
        delete pColOne ;
        pColOne = NULL ;
    }

    if ( pColTwo )
    {
        delete pColTwo ;
        pColTwo = NULL ;
    }

    return 0;
}

运行结果如下：