中介者模式

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式地互相引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。中介者模式又称调停者模式。

中介者模式实例之虚拟聊天室

从类图可知， Member关联了ChatRoom，当member发送消息时，需要经过Chatroom中介者的处理和转发到指定的member中。整体结构比较简单。

下面是c++版本的实现。

抽象中介者类AbstractChatroom（抽象聊天室类） 

class Member;
//抽象中介者类AbstractChatroom（抽象聊天室类） 
class AbstractChatroom{
public:
	virtual void registerMember(Member* member) = 0;
	virtual void sendText(string from,string to,string message) = 0;
	virtual void sendImage(string from,string to,string image) = 0;
}; 

抽象同事类Member（抽象会员类）  

//抽象同事类Member（抽象会员类） 
class Member{
public:
	Member(string name){
		this->name = name;
	}
	
	string getName(){
		return this->name;
	}
	
	void setName(string name){
		this->name = name;
	}
	
	AbstractChatroom* getChatroom(){
		return chatroom;
	}
	
	void setChatroom(AbstractChatroom* chatroom){
		this->chatroom = chatroom;
	}
	
	virtual void sendText(string to,string message) = 0;
	virtual void sendImage(string to,string image) = 0;
	
	void receiveText(string from,string message){
		cout << from << "发送文本给" << this->name << ",内容为:" << message << endl; 
	}
	
	void receiveImage(string from,string image){
		cout << from << "发送图片给" << this->name << ",内容为:" << image << endl; 
	}
	
protected:
	AbstractChatroom *chatroom;
	string name;
}; 

具体中介者类Chatgroup（具体聊天室类）  

//具体中介者类Chatgroup（具体聊天室类） 
class ChatGroup : public AbstractChatroom{
public:
	void registerMember(Member* member){
		if(!members.count(member->getName())){
			members.insert(make_pair(member->getName(),member));
			member->setChatroom(this);
		}
	}
	
	void sendText(string from,string to,string message){
		Member *member  = members[to];
		member->receiveText(from,message);
	}
	
	void sendImage(string from,string to,string image){
		Member *member  = members[to];
		if(image.length()>5){
			cout << "图片太大，发送失败！" << endl;
		}else{
			member->receiveImage(from,image);
		}
		
	}
private:
	map<string,Member*> members;
};

具体同事类CommonMember（普通会员类） 

//具体同事类CommonMember（普通会员类）
class CommonMember : public Member{
public:
	CommonMember(string name) : Member(name){
		
	}
	
	void sendText(string to,string message){
		cout << "普通会员发送信息:" << endl;
		chatroom->sendText(name,to,message);
	}
	
	void sendImage(string to,string image){
		cout << "普通会员不能发送图片!" << endl; 
	}
}; 

具体同事类DiamondMember（钻石会员类） 

//具体同事类DiamondMember（钻石会员类）
class DiamondMember : public Member{
public:
	DiamondMember(string name) : Member(name){
		
	}
	
	void sendText(string to,string message){
		cout << "钻石会员发送信息:" << endl;
		chatroom->sendText(name,to,message);
	}
	
	void sendImage(string to,string image){
		cout << "钻石会员发送图片:" << endl;
		chatroom->sendImage(name,to,image);
	}
}; 

客户端测试 

//客户端测试
int main(void){
	//创建聊天室 
	ChatGroup happyChat;
	
	//创建成员
	CommonMember member1("张三");
	DiamondMember member2("李四");
	
	//注册 
	happyChat.registerMember(&member1);
	happyChat.registerMember(&member2);
	
	//发送信息
	member1.sendText("李四","李四，你好！");
	member2.sendText("张三","张三，你好！");
	member1.sendText("李四","今天天气很不错");
	member1.sendImage("李四","好天气");
	member2.sendImage("张三","一个很大的太阳");
	member2.sendImage("张三","太阳");
} 

输出结果