设计模式学习-----观察者模式
观察者模式
GOOD:定义了一种一对多的关系,让多个观察对象(公司员工)同时监听一个主题对象(秘书),主题对象状态发生变化时,会通知所有的观察者,使它们能够更新自己。
示例:
#include <string>
#include <iostream>
#include <vector>
using namespace std;
class Secretary;
//看股票的同事类(观察对象,观察者)
class StockObserver
{
private:
string name;
Secretary* sub;
public:
StockObserver(string strname,Secretary* strsub)
{
name=strname;
sub=strsub;
}
void Update();
};
//秘书类(主题对象,通知者)
class Secretary
{
private:
vector<StockObserver> observers;
public:
string action;
void Add(StockObserver ob)
{
observers.push_back(ob);
}
void Notify()
{
vector<StockObserver>::iterator p = observers.begin();
while (p!=observers.end())
{
(*p).Update();
p++;
}
}
};
void StockObserver::Update()
{
cout<<name<<":"<<sub->action<<",不要玩股票了,要开始工作了"<<endl;
}
//客户端
int main()
{
Secretary *p=new Secretary(); //创建通知者
//观察者
StockObserver *s1= new StockObserver("小李",p);
StockObserver *s2 = new StockObserver("小赵",p);
//加入通知队列
p->Add(*s1);
p->Add(*s2);
//事件
p->action="老板来了";
//通知
p->Notify();
return 0;
}
#include <string>
#include <iostream>
#include <vector>
using namespace std;
class SecretaryBase;
//抽象观察者
class CObserverBase
{
protected:
string name;
SecretaryBase* sub;
public:
CObserverBase(string strname,SecretaryBase* strsub)
{
name=strname;
sub=strsub;
}
virtual void Update()=0;
};
//具体的观察者,看股票的
class StockObserver : public CObserverBase
{
public:
StockObserver(string strname,SecretaryBase* strsub) : CObserverBase(strname,strsub)
{
}
virtual void Update();
};
//具体观察者,看NBA的
class NBAObserver : public CObserverBase
{
public:
NBAObserver(string strname,SecretaryBase* strsub) : CObserverBase(strname,strsub){}
virtual void Update();
};
//抽象通知者
class SecretaryBase
{
public:
string action;
vector<CObserverBase*> observers;
public:
virtual void Attach(CObserverBase* observer)=0;
virtual void Notify()=0;
};
//具体通知者
class Secretary :public SecretaryBase
{
public:
void Attach(CObserverBase* ob)
{
observers.push_back(ob);
}
void Notify()
{
vector<CObserverBase*>::iterator p = observers.begin();
while (p!=observers.end())
{
(*p)->Update();
p++;
}
}
};
void StockObserver::Update()
{
cout<<name<<":"<<sub->action<<",不要玩股票了,要开始工作了"<<endl;
}
void NBAObserver::Update()
{
cout<<name<<":"<<sub->action<<",不要看NBA了,老板来了"<<endl;
}
//客户端:
int main()
{
SecretaryBase *p=new Secretary(); //创建观察者
//被观察的对象
CObserverBase *s1= new NBAObserver("小李",p);
CObserverBase *s2 = new StockObserver("小赵",p);
//加入观察队列
p->Attach(s1);
p->Attach(s2);
//事件
p->action="老板来了";
//通知
p->Notify();
return 0;
}
补充:软件开发 , Java ,