--------------------------------------------- -- 時間：2019-03-22 -- 創建人：Ruo_Xiao -- 郵箱：xclsoftware@163.com ---------------------------------------------

一、解釋

1、結構：分為目標和觀察者。

2、功能：當目標更新時，該模式可以將該更新內容發布給所有的該目標的觀察者。

3、實際上，目標通過抽象類得到觀察者的接口，然后在其內建立觀察者的鏈表，當發布時直接按照同一個接口（面向接口編程）向所有的觀察者的更新。

二、代碼

#include <iostream> #include <list> using namespace std;// 觀察者……抽象類 class Observe { public:virtual void Update(int i) = 0;virtual void Attach() = 0;virtual void Detach() = 0; };// 目標……抽象類 class Subject { public:virtual void Attach(Observe *p) = 0;virtual void Detach(Observe *p) = 0;virtual void Notify() = 0; };// 建立3個觀察者、1個目標 class Observe_1 : public Observe { public:Observe_1(Subject *p){m_pSubject = p;} public:void Attach(){m_pSubject->Attach(this);}void Detach(){m_pSubject->Detach(this);}void Update(int i){cout<<"I am observe 1,showing "<< i <<endl;} private:Subject *m_pSubject; };class Observe_2 : public Observe { public:Observe_2(Subject *p){m_pSubject = p;} public:void Attach(){m_pSubject->Attach(this);}void Detach(){m_pSubject->Detach(this);}void Update(int i){cout<<"I am observe 2,showing "<< i <<endl;} private:Subject *m_pSubject; };class Observe_3 : public Observe { public:Observe_3(Subject *p){m_pSubject = p;} public:void Attach(){m_pSubject->Attach(this);}void Detach(){m_pSubject->Detach(this);}void Update(int i){cout<<"I am observe 3,showing "<< i <<endl;} private:Subject *m_pSubject; };class Subject_All : public Subject { public:void Attach(Observe *p){pObserverList.push_back(p);}void Detach(Observe *p){pObserverList.remove(p);}void Notify(){list<Observe *>::iterator it = pObserverList.begin();for (;it!=pObserverList.end();++it){(*it)->Update(iState_All);}}void SetState(int iState){iState_All = iState;} private:list<Observe *> pObserverList;int iState_All; };int main() {// Create SubjectSubject_All *pSubject = new Subject_All();// Create ObserverObserve_1 *pObserver1 = new Observe_1(pSubject);Observe_2 *pObserver2 = new Observe_2(pSubject);Observe_3 *pObserver3 = new Observe_3(pSubject);// Change the statepSubject->SetState(2);// Register the observerpObserver1->Attach();pObserver2->Attach();pObserver3->Attach();pSubject->Notify();// Unregister the observerpObserver3->Detach();pSubject->SetState(3);pSubject->Notify();delete pObserver1;delete pObserver2;delete pObserver3;delete pSubject;cin.get(); }

結果：

（SAW：Game Over！）

總結

以上是生活随笔為你收集整理的C/Cpp / 设计模式 / 观察者模式的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。