observer.cpp

来自「详细介绍了20种设计模式的具体实现框架,很有参考价值」· C++ 代码 · 共 110 行

/********************************************************************
	created:	2006/07/20
	filename: 	Observer.cpp
	author:		李创
                http://www.cppblog.com/converse/

	purpose:	Observer模式的演示代码
*********************************************************************/

#include "Observer.h"
#include <iostream>
#include <algorithm>

/* --------------------------------------------------------------------
|	Subject类成员函数的实现
|
 ----------------------------------------------------------------------*/

void Subject::Attach(Observer *pObserver)
{
	std::cout << "Attach an Observer\n";

	m_ListObserver.push_back(pObserver);
}

void Subject::Detach(Observer *pObserver)
{
	std::list<Observer*>::iterator iter;
	iter = std::find(m_ListObserver.begin(), m_ListObserver.end(), pObserver);

	if (m_ListObserver.end() != iter)
	{
		m_ListObserver.erase(iter);
	}

	std::cout << "Detach an Observer\n";
}

void Subject::Notify()
{
	std::cout << "Notify Observers's State\n";

	std::list<Observer*>::iterator iter1, iter2;

	for (iter1 = m_ListObserver.begin(), iter2 = m_ListObserver.end();
		 iter1 != iter2;
		 ++iter1)
	{
		(*iter1)->Update(this);
	}
}

void Subject::SetState(STATE nState)
{
	std::cout << "SetState By Subject\n";
	m_nSubjectState = nState;
}

STATE Subject::GetState()
{
	std::cout << "GetState By Subject\n";
	return m_nSubjectState;
}

Subject::~Subject()
{
	std::list<Observer*>::iterator iter1, iter2, temp;

	for (iter1 = m_ListObserver.begin(), iter2 = m_ListObserver.end();
		iter1 != iter2;
		)
	{
		temp = iter1;
		++iter1;
		delete (*temp);
	}

	m_ListObserver.clear();
}

/* --------------------------------------------------------------------
|	ConcreateSubject类成员函数的实现
|
----------------------------------------------------------------------*/
void ConcreateSubject::SetState(STATE nState)
{
	std::cout << "SetState By ConcreateSubject\n";
	m_nSubjectState = nState;
}

STATE ConcreateSubject::GetState()
{
	std::cout << "GetState By ConcreateSubject\n";
	return m_nSubjectState;
}

/* --------------------------------------------------------------------
|	ConcreateObserver类成员函数的实现
|
----------------------------------------------------------------------*/
void ConcreateObserver::Update(Subject* pSubject)
{
	if (NULL == pSubject)
		return;

	m_nObserverState = pSubject->GetState();

	std::cout << "The ObeserverState is " << m_nObserverState << std::endl;
}