本文共 1736 字，大约阅读时间需要 5 分钟。

状态模式

定义：当一个对象的内在状态改变时，允许改变它的行为，这个对象看起来像是改变了其类。

它属于行为型模式

栗子场景：一天根据当前的时间段，来决定一个人是吃早饭还是午饭以及晚饭。即根据时间的状态变化，改变人吃什么的行为。

代码：

#include 
   
    #include 
    
     using namespace std;class Eat;class MealStatus{public:	virtual void doEat(Eat *eat) = 0;};class Eat{public:	Eat(MealStatus *m) :m_status(nullptr)	{		m_status = m;	}	~Eat()	{		if (m_status)		{			delete m_status;			m_status = nullptr;		}	}	void request()	{		m_status->doEat(this);	}	void setStatus(MealStatus* s)	{		m_status = s;	}	void setHour(int h)	{		m_hour = h;	}	int getHour()	{		return m_hour;	}private:	MealStatus* m_status;	int m_hour;};//夜宵class NightSnack :public MealStatus{public:	NightSnack(){}	void doEat(Eat *eat)	{		cout << "吃夜宵时间段来了，吃货的一天准备结束啦" << " current-time=" << eat->getHour() << endl;	}};//晚餐class Dinner :public MealStatus{public:	Dinner(){}	void doEat(Eat *eat)	{		if (eat->getHour() < 21)		{			cout << "吃晚饭时间段" << " current-time=" << eat->getHour() << endl;		}		else		{			eat->setStatus(new NightSnack);			eat->request();		}			}};//午餐class Lunch :public MealStatus{public:	Lunch(){}	void doEat(Eat *eat)	{		if (eat->getHour()<14)		{			cout << "吃午饭时间段" << " current-time="<
     
      getHour()<
      
       setStatus(new Dinner);			eat->request();		}	}};//早餐class Breakfast :public MealStatus{public:	Breakfast(){}	void doEat(Eat *eat)	{		if (eat->getHour() < 9)		{			cout << "吃早饭时间段" << " current-time=" << eat->getHour()<< endl;		}		else		{			eat->setStatus(new Lunch);			eat->request();		}	}};int main(){	Eat *eat = new Eat(new Breakfast);	//切换状态	eat->setHour(8);	eat->request();	eat->setHour(13);	eat->request();	eat->setHour(20);	eat->request();	eat->setHour(24);	eat->request();	if (eat)	{		delete eat;		eat = nullptr;	}	return 0;}
      
     
    
   

效果

转载地址：https://blog.csdn.net/c_shell_python/article/details/107486700 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！