設計模式之——觀察者模式

boss.h

#ifndef BOSS_H
#define BOSS_H
#include <QList>
#include "observer.h"
#include "subject.h"


class Boss : public Subject
{
public:
    Boss() {}
    void attach(Observer *observer){ observers.append(observer);}
    void detach(Observer *observer)
    {
        for(int i = observers.count(); i > 0; i--)
        {
            if(observers.at(i) == observer)
            {
                observers.removeAt(i);
            }
        }
    }
    void notify()
    {
        QList<Observer *>::iterator it = observers.begin();
        while (it != observers.end())
        {
            (*it)->update();
            ++it;
        }
    }
};

#endif // BOSS_H

observer.h

#ifndef OBSERVER_H
#define OBSERVER_H
#include <QString>
#include "subject.h"

class Observer
{
public:
    Observer(QString name,Subject *sub):m_name(name),m_sub(sub){}
    virtual void update() = 0;

protected:
    QString m_name;
    Subject *m_sub;
};


#endif // OBSERVER_H

subject.h

#ifndef SUBJECT_H
#define SUBJECT_H
#include "observer.h"
#include <QList>

class Observer;

class Subject
{
public:
    Subject(){}
    virtual void attach(Observer *observer)=0;
    virtual void detach(Observer *observer)=0;
    virtual void notify()=0;
    QString m_action;
protected:
    QList<Observer *> observers;
};

#endif // SUBJECT_H

stockObserver.h

#ifndef STOCKOBSERVER_H
#define STOCKOBSERVER_H
#include <QString>
#include <QtDebug>

#include "observer.h"
#include "subject.h"

class StockObserver : public Observer
{
public:
    StockObserver(QString name, Subject *sub):Observer(name,sub){}
    void update(){ qDebug() << m_name << " 收到消息：" << m_sub->m_action ;}
};

#endif // STOCKOBSERVER_H

main

#include <QApplication>
#include "boss.h"
#include "stockObserver.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Boss *boss = new Boss();

    StockObserver *xiaoming = new StockObserver("小明",boss);
    boss->attach(xiaoming);

    boss->m_action = "我回來了";
    boss->notify();

    return a.exec();
}

UML