2.C++设计模式 - 观察者模式

class Observer {
public:
	//构造
	Observer(){ }
	//析构
	virtual ~Observer(){ }
	//更新
	virtual void updata(){ }
};

class Server {
private:
	//观察者链表
	list<Observer*> m_Observer;

protected:
	//服务器状态
	string m_Status;

public:
	//构造函数
	Server(){ }
	//析构函数
	virtual ~Server(){ }
	//添加观察者
	void Attach(Observer* observer) {
		this->m_Observer.push_back(observer);
	}
	//移除观察者
	void Remove(Observer* observer) {
		this->m_Observer.remove(observer);
	}
	//设置服务器状态
	virtual void SetStatus(string s){ }
	//获取服务器状态
	virtual string GetStatus() {
		return this->m_Status;
	}
	//通知观察者
	void Notify() {
		for (list<Observer*>::iterator iter = this->m_Observer.begin();iter != m_Observer.end(); iter++) {
			(*iter)->updata();
		}
	}
};

//具体服务器
class Concrete_Server : public Server {
private:
	//用户名称
	string m_Name;
public:
	//构造
	Concrete_Server(string name) {
		this->m_Name = name;
	}
	//析构
	~Concrete_Server(){ }
	//设置服务器状态
	virtual void SetStatus(string s) { 
		this->m_Status = "("+this->m_Name+")"+s;
	}
	//获取服务器状态
	virtual string GetStatus() {
		return this->m_Status;
	}
};

//具体观察者
class Concrete_Observer : public Observer {
private:
	//观察者名称
	string m_Name;
	//需要观察的服务器
	Server* m_Server;
public:
	//构造
	Concrete_Observer(string name, Server* server) {
		this->m_Name = name;
		this->m_Server = server;
	}
	//析构
	~Concrete_Observer(){ }
	//更新
	virtual void updata() {
		cout << this->m_Name << ": " << this->m_Server->GetStatus() << endl;
	}
};

void test() {
	Server* server1 = new Concrete_Server("服务器1");

	Observer* observer1 = new Concrete_Observer("观察者1", server1);
	Observer* observer2 = new Concrete_Observer("观察者2", server1);
	server1->Attach(observer1);
	server1->Attach(observer2);
	server1->SetStatus("2.1.0.001更新系统");
	server1->Notify();

	delete server1;
	server1 = NULL;
	delete observer1;
	observer1 = NULL;
}


int main()
{
	test();
	system("pause");
	return 0;
}