C++ 事件机制实现

一. 先看看事件接口和实现
#ifndef IEVENT_H
#define IEVENT_H
/*
以下各基础设施是在C++中事件机制的完整实现，事件是面向组件开发的必要特性之一。
最开始打算用函数指针模拟事件，但由于C++中成员函数指针不能和void*相互强转，而且
typedef中不能含有模板，所以才不得已以接口继承实现。这样效果也不错 :)

创 作 者：sky
时 间：2005.06.22
修订时间：2005.06.22
*/
#include "../Collection/SafeArrayList.h"
template<class SenderType ,class ParaType> class EventPublisher ;
class NullType
{
};
// IEventHandler 是事件处理句柄，预定事件的类从此接口继承以实现事件处理函数
template<class SenderType ,class ParaType>
interface IEventHandler
{
public:
virtual ~IEventHandler(){}
private:
virtual void HandleEvent(SenderType sender ,ParaType para) = 0 ;
friend class EventPublisher<SenderType ,ParaType> ;
};
// IEvent 事件预定方通过此接口预定事件
template<class SenderType ,class ParaType>
interface IEvent
{
public:
virtual ~IEvent(){}
virtual void Register (IEventHandler<SenderType ,ParaType>* handler) = 0 ;
virtual void UnRegister(IEventHandler<SenderType ,ParaType>* handler) = 0 ;
};
// IEventActivator 事件发布方通过此接口触发事件
template<class SenderType ,class ParaType>
interface IEventActivator
{
public:
virtual ~IEventActivator(){}
virtual void Invoke(SenderType sender ,ParaType para) = 0;
virtual int HandlerCount() = 0;
virtual IEventHandler<SenderType ,ParaType>* GetHandler(int index) = 0;
};
// IEventPublisher 事件发布方发布事件相当于就是发布一个IEventPublisher派生类的对象
// 不过仅仅将该对象的IEvent接口发布即可。
template<class SenderType ,class ParaType>
interface IEventPublisher : public IEvent<SenderType ,ParaType> ,public IEventActivator<SenderType ,ParaType>
{
};
// EventPublisher是IEventPublisher的默认实现
template<class SenderType ,class ParaType>
class EventPublisher :public IEventPublisher<SenderType ,ParaType>
{
private:
SafeArrayList< IEventHandler<SenderType ,ParaType> > handerList ;
IEventHandler<SenderType ,ParaType>* innerHandler ;
public:
void Register(IEventHandler<SenderType ,ParaType>* handler)
{
this->handerList.Add(handler) ;
}
void UnRegister(IEventHandler<SenderType ,ParaType>* handler)
{
this->handerList.Remove(handler) ;
}
void Invoke(SenderType sender ,ParaType para)
{
int count = this->handerList.Count() ;
for(int i=0 ;i<count ;i++)
{
IEventHandler<SenderType ,ParaType>* handler = this->handerList.GetElement(i) ;
handler->HandleEvent(sender ,para) ;
}
}
int HandlerCount()
{
return this->handerList.Count() ;
}
IEventHandler<SenderType ,ParaType>* GetHandler(int index)
{
return this->handerList.GetElement(index) ;
}
};
#endif

二. 一个定时器类Timer，演示如何发布事件。想必大家都知道定时器的用途了哦，这个Timer就像C#中的Timer类一样。
#ifndef TIMER_H
#define TIMER_H
/*
Timer 定时器,每经过一段指定时间就触发事件

创 作 者：sky
时 间：2005.06.22
修订时间：2005.06.22
*/
#include "IEvent.h"
#include "Thread.h"
void TimerThreadStart(void* para) ;
class Timer
{
private:
int spanInMillSecs ;
volatile bool isStop ;
volatile bool timerThreadDone ;

public:
friend void TimerThreadStart(void* para) ;
IEvent<Timer* ,NullType>* TimerTicked ;
Timer(int span_InMillSecs)
{
this->isStop = true ;
this->timerThreadDone = true ;
this->spanInMillSecs = span_InMillSecs ;
this->TimerTicked = new EventPublisher<Timer* ,NullType> ;
}

~Timer()
{
this->Stop() ;
delete this->TimerTicked ;
}
void Start()
{
if(! this->isStop)
{
return ;
}
this->isStop = false ;
Thread thread ;
thread.Start(TimerThreadStart ,this) ;
//unsigned int dwThreadId ;
//HANDLE hThread = (HANDLE)_beginthreadex(NULL, 0 , (unsigned int (_stdcall*)(void*))&TimerThreadStart , this, 0, &dwThreadId);

}
void Stop()
{
if( this->isStop)
{
return ;
}

this->isStop = true ;
//等待工作线程退出
while(! this->timerThreadDone)
{
Sleep(200) ;
}
}
private:
void WorkerThread()
{
this->timerThreadDone = false ;
while(! this->isStop)
{
Sleep(this->spanInMillSecs) ;
if(this->isStop)
{
break ;
}

NullType nullObj ;
((EventPublisher<Timer* ,NullType>*)this->TimerTicked)->Invoke(this ,nullObj) ;
}
this->timerThreadDone = true ;
}
};
void TimerThreadStart(void* para)
{
Timer* timer = (Timer*)para ;
timer->WorkerThread() ;
}
#endif

三. 预定事件例子
class TimerEventExample :public IEventHandler<Timer* ,NullType> ,CriticalSection
{
private:
Timer* timer ;

public:
TimerEventExample(int checkSpan)
{
this->timer = new Timer(checkSpan) ;
this->timer->TimerTicked->Register(this) ;
}
~TimerEventExample()
{
delete this->timer ;
}
private:
//处理定时事件
void HandleEvent(Timer* sender ,NullType para)
{
cout<<"Time ticked !"<<endl ;
}
};