Cocos2d-x常用设计模式—观察者模式
发表于2017-12-21
观察者模式就是发送一个消息，让观察者执行某个动作，可用于数据传递，以可以用于消息传递。上一篇给大家介绍了Cocos2d-x的单例模式，下面我们继续介绍Cocos2d-x常用的设计模式，观察者模式。
一、动机及适用情况
二、类图
三、C++代码实现
3.1 头文件Observer.h
#include <iostream>
#include <list>
using namespace std;
// 抽象类
class Observer
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public:
virtual void update() = 0;
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class Subject
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public:
virtual void attachObserver(Observer*) = 0;
virtual void detachObserver(Observer*) = 0;
virtual void notifyObservers() = 0;
｝;
// 具体类
class ConcreteObeserver :public Observer
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public:
ConcreteObeserver(Subject* pSubject);
virtual void update();
private:
Subject* m_pSubject;
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class ConcreteObserver2 : public Observer
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public:
ConcreteObserver2(Subject* pSubject);
virtual void update();
private:
Subject* m_pSubject;
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class ConcreteSubject :public Subject
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public:
virtual void attachObserver(Observer*);
virtual void detachObserver(Observer*);
virtual void notifyObservers();
private:
list<Observer*> m_observer;
｝;
3.2 cpp文件Observer.cpp
#include "Observer.h"
// 具体观察者的实现（定义）
ConcreteObeserver::ConcreteObeserver(Subject* pSubject) :m_pSubject(pSubject)
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void ConcreteObeserver::update()
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cout << "override method update of ConcreteObserver class " << endl;
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ConcreteObserver2::ConcreteObserver2(Subject* pSubject) :m_pSubject(pSubject)
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void ConcreteObserver2::update()
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cout << "override method update of ConcreteObserver2 class " << endl;
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// 具体目标（被观察者）的实现
void ConcreteSubject::attachObserver(Observer* observer)
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m_observer.push_back(observer);
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void ConcreteSubject::detachObserver(Observer* observer)
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m_observer.remove(observer);
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void ConcreteSubject::notifyObservers()
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for (auto it = m_observer.begin(); it != m_observer.end(); it++)// list<Observer*>::iterator it = m_observer.begin()
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(*it)->update();
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void main()
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// 创建具体目标和具体观察者实例
ConcreteSubject* pSubject = new ConcreteSubject();
ConcreteObeserver* pObserver = new ConcreteObeserver(pSubject);
ConcreteObserver2* pObserver2 = new ConcreteObserver2(pSubject);
// 目标对象注册观察者
pSubject->attachObserver(pObserver);
pSubject->attachObserver(pObserver2);
// 通知所有观察者
pSubject->notifyObservers();
// 释放资源
delete pSubject;
delete pObserver;
delete pObserver2;
cin.get();
｝
3.3 执行结果
