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Chapter14—中介者模式

news 2025/10/31 7:38:18

中介者模式

1 概念

用一个中介对象来封装一系列的对象交互，中介者使各对象不需要显示地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。中介者模式又称为调停者模式，它是一种对象行为型模式。

2 意图(Intent)

用一个中介对象来封装一系列对象交互。中介者使各对象不需要相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。

3 动机(Motivate)

在软件构建过程中，经常会出现多个对象互相关联交互的情况，对象之间常常会维持一种复杂的引用关系，如果遇到一些需求的更改，这种直接的引用关系将面临不断的变化。在这种情况下，我们可使用一个“中介对象”来管理对象间的关联关系，避免相互交互的对象之间的紧耦合引用关系，从而更好地抵御变化。

4 类图结构

在这里插入图片描述

5 角色定义

Mediator（抽象中介者）：抽象中介者用于定义一个接口，该接口用于与各同事对象之间的通信。
ConcreteMediator（具体中介者）：具体中介者是抽象中介者的子类，通过协调各个同事对象来实现协作行为，了解并维护它对各个同事对象的引用。在通用的中介者模式类图中，具体中介者与各个具体同事类之间有关联关系，在实现时为了保证系统的扩展性，可以根据需要将该引用关联关系建立在抽象层，即具体中介者中定义的是抽象同事角色。
Colleague（抽象同事类）：抽象同事类定义各同事的公用方法。
ConcreteColleague（具体同事类）：具体同事类是抽象同事类的子类，每一个同事对象都引用一个中介者对象；每一个同事对象在需要和其他同事对象通信时，先与中介者通信，通过中介者来间接完成与其他同事类的通信；在具体同事类中实现了在抽象同事类中声明的抽象方法。

6 程序示例

中介者示例

抽象中介者

class Mediator
{
public:Mediator() = default;virtual ~Mediator() = default;public:virtual void DoActionFromAtoB() = 0;virtual void DoActionFromBtoA() = 0;
};

抽象同事类

class Colleage
{
public:Colleage() = default;virtual ~Colleage() = default;Colleage(Mediator* pMediator);public:virtual void Aciton() = 0;void SetState(const string& strState);string GetState();protected:Mediator* m_pMediator;string m_strState;
};Colleage::Colleage(Mediator *pMediator) : m_pMediator(pMediator)
{// ...
}void Colleage::SetState(const string &strState)
{m_strState = strState;
}string Colleage::GetState()
{return m_strState;
}

具体同事类A

class ConcreteColleageA: public Colleage
{
public:ConcreteColleageA() = default;virtual ~ConcreteColleageA() = default;ConcreteColleageA(Mediator* pMediator);public:void Aciton();
};ConcreteColleageA::ConcreteColleageA(Mediator *pMediator) : Colleage(pMediator)
{// ...
}void ConcreteColleageA::Aciton()
{m_pMediator->DoActionFromAtoB();qDebug() << "State of ConcreteColleageA:" << this->GetState().c_str();
}

具体同事类B

class ConcreteColleageB: public Colleage
{
public:ConcreteColleageB() = default;virtual ~ConcreteColleageB() = default;ConcreteColleageB(Mediator* pMediator);public:void Aciton();
};ConcreteColleageB::ConcreteColleageB(Mediator *pMediator) : Colleage(pMediator)
{// ...
}void ConcreteColleageB::Aciton()
{m_pMediator->DoActionFromBtoA();qDebug() << "State of ConcreteColleageB:" << this->GetState().c_str();
}

具体中介者类

class ConcreteMediator: public Mediator
{
public:ConcreteMediator() = default;~ConcreteMediator() = default;ConcreteMediator(Colleage* pColleageA, Colleage* pColleageB);public:void SetConcreteColleageA(Colleage* pColleageA);void SetConcreteColleageB(Colleage* pColleageB);Colleage* GetConcreteColleageA();Colleage* GetConcreteColleageB();void IntroColleage(Colleage* pColleageA, Colleage* pColleageB);void DoActionFromAtoB();void DoActionFromBtoA();private:Colleage* m_pColleageA;Colleage* m_pColleageB;
};ConcreteMediator::ConcreteMediator(Colleage *pColleageA, Colleage *pColleageB):m_pColleageA(), m_pColleageB(pColleageB)
{// ...
}void ConcreteMediator::SetConcreteColleageA(Colleage *pColleageA)
{m_pColleageA = pColleageA;
}void ConcreteMediator::SetConcreteColleageB(Colleage *pColleageB)
{m_pColleageB = pColleageB;
}Colleage *ConcreteMediator::GetConcreteColleageA()
{return m_pColleageA;
}Colleage *ConcreteMediator::GetConcreteColleageB()
{return m_pColleageB;
}void ConcreteMediator::IntroColleage(Colleage *pColleageA, Colleage *pColleageB)
{m_pColleageA = pColleageA;m_pColleageB = pColleageB;
}void ConcreteMediator::DoActionFromAtoB()
{m_pColleageB->SetState(m_pColleageA->GetState());
}void ConcreteMediator::DoActionFromBtoA()
{m_pColleageA->SetState(m_pColleageB->GetState());
}

测试函数类

void ClientTest()
{ConcreteMediator* pConcreteMediator = new ConcreteMediator();ConcreteColleageA* pColleageA = new ConcreteColleageA(pConcreteMediator);ConcreteColleageB* pColleageB = new ConcreteColleageB(pConcreteMediator);pConcreteMediator->IntroColleage(pColleageA, pColleageB);pColleageA->SetState("old");pColleageB->SetState("old");pColleageA->Aciton();pColleageB->Aciton();pColleageA->SetState("new");pColleageA->Aciton();pColleageB->Aciton();pColleageB->SetState("old");pColleageB->Aciton();pColleageA->Aciton();delete pConcreteMediator;delete pColleageA;delete pColleageB;
}

虚拟聊天室示例

示例类图

在这里插入图片描述

抽象中介者类 AbstractChatroom (抽象聊天室类)

class Member;/*** @brief 抽象中介者类 AbstractChatroom (抽象聊天室类)*/
class AbstractChatroom
{
public:AbstractChatroom() = default;virtual ~AbstractChatroom() = default;public:virtual void Rergister(Member* pMember) = 0;virtual void SendText(const string& strFrom, const string& strTo, const string& strMessage) = 0;virtual void SendImage(const string& strFrom, const string& strTo, const string& strImage) = 0;
};

抽象同事类 Member (抽象会员类)

/*** @brief 抽象同事类 Member (抽象会员类)*/
class Member
{
public:Member(const string& strName);virtual ~Member() = default;public:void SetName(const string& strName);string GetName();void SetChatroom(AbstractChatroom* pChatroom);AbstractChatroom* GetChatroom();void ReceiveText(const string& strFrom, const string& strMessage);void ReceiveImage(const string& strFrom, const string& strImage);virtual void SendText(const string& strTo, const string& strMessage) = 0;virtual void SendImage(const string& strTo, const string& strImage) = 0;protected:AbstractChatroom* m_pChatroom;string m_strName;
};Member::Member(const string &strName): m_strName(strName)
{// ...
}void Member::SetName(const string &strName)
{m_strName = strName;
}string Member::GetName()
{return m_strName;
}void Member::SetChatroom(AbstractChatroom *pChatroom)
{m_pChatroom = pChatroom;
}AbstractChatroom *Member::GetChatroom()
{return m_pChatroom;
}void Member::ReceiveText(const string &strFrom, const string &strMessage)
{qDebug() << strFrom.c_str() << "发送文本给" << m_strName.c_str() << "，内容为：" << strMessage.c_str();
}void Member::ReceiveImage(const string &strFrom, const string &strImage)
{qDebug() << strFrom.c_str() << "发送图片给" << m_strName.c_str() << "，内容为：" << strImage.c_str();
}

具体中介者类 ChatGroup (具体聊天室类)

/*** @brief 具体中介者类 ChatGroup (具体聊天室类)*/
class ChatGroup: public AbstractChatroom
{
public:ChatGroup() = default;~ChatGroup() = default;public:void Rergister(Member* pMember) override;void SendText(const string& strFrom, const string& strTo, const string& strMessage) override;void SendImage(const string& strFrom, const string& strTo, const string& strImage) override;private:map<string, Member*> m_MapName2Member;
};void ChatGroup::Rergister(Member *pMember)
{m_MapName2Member[pMember->GetName()] = pMember;pMember->SetChatroom(this);
}void ChatGroup::SendText(const string &strFrom, const string &strTo, const string &strMessage)
{Member* pMember = m_MapName2Member[strTo];pMember->ReceiveText(strFrom, strMessage);
}void ChatGroup::SendImage(const string &strFrom, const string &strTo, const string &strImage)
{Member* pMember = m_MapName2Member[strTo];if (strImage.length() > 10){qDebug() << "图片太大，发送失败！";}else{pMember->ReceiveImage(strFrom, strImage);}
}

具体同事类 CommonMember(普通会员类)

/*** @brief 具体同事类 CommonMember(普通会员类)*/
class CommonMember: public Member
{
public:CommonMember(const string& strName);~CommonMember() = default;public:void SendText(const string& strTo, const string& strMessage) override;void SendImage(const string& strTo, const string& strImage) override;
};CommonMember::CommonMember(const string &strName): Member(strName)
{// ...
}void CommonMember::SendText(const string &strTo, const string &strMessage)
{qDebug() << "普通会员发送信息：";m_pChatroom->SendText(m_strName, strTo, strMessage);    // 发送文本
}void CommonMember::SendImage(const string &strTo, const string &strImage)
{qDebug() << "普通会员不能发送图片！";
}

具体同事类 DiamondMember(钻石会员类)

/*** @brief 具体同事类 DiamondMember(钻石会员类)*/
class DiamondMember: public Member
{
public:DiamondMember(const string& strName);~DiamondMember() = default;public:void SendText(const string& strTo, const string& strMessage) override;void SendImage(const string& strTo, const string& strImage) override;
};DiamondMember::DiamondMember(const string &strName): Member(strName)
{// ...
}void DiamondMember::SendText(const string &strTo, const string &strMessage)
{qDebug() << "钻石会员发送信息：";m_pChatroom->SendText(m_strName, strTo, strMessage);    // 发送文本
}void DiamondMember::SendImage(const string &strTo, const string &strImage)
{qDebug() << "钻石会员发送图片：";m_pChatroom->SendImage(m_strName, strTo, strImage);    // 发送图片
}

测试函数

/*** @brief 测试函数*/
void ClientTest()
{AbstractChatroom* pChatroom = new ChatGroup();Member* pMember1 = new DiamondMember("张三");Member* pMember2 = new DiamondMember("李四");Member* pMember3 = new DiamondMember("王五");Member* pMember4 = new CommonMember("小芳");Member* pMember5 = new CommonMember("小红");pChatroom->Rergister(pMember1);pChatroom->Rergister(pMember2);pChatroom->Rergister(pMember3);pChatroom->Rergister(pMember4);pChatroom->Rergister(pMember5);pMember1->SendText("李四", "李四，你好！");pMember2->SendText("张三", "张三，你好！");pMember1->SendText("李四", "今天天气不错，有太阳！");pMember2->SendImage("张三", "一个很大很大的太阳！");pMember2->SendImage("张三", "太阳");pMember3->SendText("小芳", "还有问题吗？");pMember3->SendText("小红", "还有问题吗？");pMember4->SendText("王五", "没有了，谢谢！");pMember5->SendText("小红", "我也没有了！");pMember5->SendImage("王五", "谢谢！");delete pChatroom;delete pMember1;delete pMember2;delete pMember3;delete pMember4;delete pMember5;
}