C++设计模式学习之一（共计13种）

2023-12-13 19:52:34

1）简单工厂模式

#include <iostream>
#include <memory>
//简单工厂模式
//产品基类
class Productor
{
public:
	virtual void doWork(void) = 0;
};
//产品A
class ProductorA : public Productor
{
public:
	virtual void doWork(void) override
	{
		printf("ProductorA output\r\n");
	}
};
//产品B
class ProductorB : public Productor
{
public:
	virtual void doWork(void) override
	{
		printf("ProductorB output\r\n");
	}
};
//工厂基类
class Factory
{
public:
	virtual std::unique_ptr<Productor> CreateProduct() = 0;
};
//工厂A
class DerivedCreateA : public Factory
{
public:
	virtual std::unique_ptr<Productor> CreateProduct()
	{
		return std::make_unique<ProductorA>();
	}
};
//工厂B
class DerivedCreateB : public Factory
{
public:
	virtual std::unique_ptr<Productor> CreateProduct()
	{
		return std::make_unique<ProductorB>();
	}
};
int main(void)
{
	//创建工厂A
	DerivedCreateA fa;
	auto pa = fa.CreateProduct(); //产出pa产品
	pa->doWork(); //执行a产品的工作函数
	//创建工厂B
	DerivedCreateB fb;
	auto pb = fb.CreateProduct(); //产出pb产品
	pb->doWork(); //执行b产品的工作函数
	return 0;
}

2）builder-建造者模式

#include<iostream>
#include<string>
#include<vector>

using namespace std;
//抽象产品类
class AbstractProduct
{
public:
	virtual void setDisplayer(string displayer) = 0;
	virtual void setHost(string host) = 0;
	virtual void setKeyBoard(string keyboard) = 0;
	virtual void setMouse(string mouse) = 0;
	virtual void showConfig(void) = 0;
};
//具体产品类
class Computer : public AbstractProduct
{
public:
	virtual void setDisplayer(string displayer)
	{
		_list.push_back(displayer);
	}
	virtual void setHost(string host)
	{
		_list.push_back(host);
	}
	virtual void setKeyBoard(string keyboard)
	{
		_list.push_back(keyboard);
	}
	virtual void setMouse(string mouse)
	{
		_list.push_back(mouse);
	}
	virtual void showConfig(void)
	{
		cout << "computer config is" << endl;
		for (auto e : _list)
		{
			cout << e << endl;
		}
	}
	vector<string> _list;
};
//抽象建造者类
class AbstractBuilder
{
public:
	AbstractBuilder(): product(new Computer){}
	//抽象构造过程
	virtual void BuildDisplayer(string display) = 0;
	virtual void BuildMouse(string mouse) = 0;
	virtual void BuildKeyBoard(string keyBoard) = 0;
	virtual void BuildHost(string host) = 0;
	AbstractProduct* Getproduct()
	{
		return product;
	}
protected:
	AbstractProduct* product;
};
//具体建造者
class ConcreteBuilder : public AbstractBuilder
{
public:
	virtual void BuildDisplayer(string display)override
	{
		product->setDisplayer(display);
	}
	virtual void BuildMouse(string mouse)override
	{
		product->setMouse(mouse);
	}
	virtual void BuildKeyBoard(string keyBoard)override
	{
		product->setKeyBoard(keyBoard);
	}
	virtual void BuildHost(string host)override
	{
		product->setHost(host);
	}
};
//指挥者类
class Director
{
public:
	Director(AbstractBuilder* pBuilder):_pBuilder(pBuilder){}
	AbstractProduct* createProduct(string displayer, string mouse, string keyboard, string host)
	{
		_pBuilder->BuildDisplayer(displayer);
		_pBuilder->BuildMouse(mouse);
		_pBuilder->BuildKeyBoard(keyboard);
		_pBuilder->BuildHost(host);
		return _pBuilder->Getproduct();
	}
private:
	AbstractBuilder* _pBuilder;
};
int main(void)
{
	AbstractBuilder* pb = new ConcreteBuilder;
	Director* pd = new Director(pb);
	AbstractProduct* computer = pd->createProduct("华为显示器", "牧马人鼠标", "雷蛇键盘", "外星人");
	computer->showConfig();
	return 0;
}

3）prototype-原型模式

#include <iostream>
#include <memory>
#include <string>
using namespace std;

class Monkey
{
public:
	Monkey() = default;
	virtual ~Monkey(){}
	virtual Monkey* Clone() = 0;
	virtual void Play() = 0;
};
//2变化
class SunWuKong : public Monkey
{
public:
	SunWuKong(string name) : _name(name){}
	SunWuKong(const SunWuKong& obj)
	{
		_name = obj._name;
	}
	Monkey* Clone()
	{
		//调用拷贝构造函数,目前用的是浅拷贝
		return new SunWuKong(*this);
	}
	virtual void Play()
	{
		cout << _name << ",玩金箍棒" << endl;
	}
private:
	string _name;
};
int main(void)
{
	Monkey* monkey = new SunWuKong("齐天大圣");
	Monkey* monkey1 = monkey->Clone();
	Monkey* monkey2 = monkey->Clone();
	monkey->Play();
	monkey1->Play();
	monkey2->Play();
	delete monkey;
	delete monkey1;
	delete monkey2;

	return 0;
}

4）proxy-代理模式

#include <iostream>
#include <memory>
#include <string>
using namespace std;

/*
1.提供一个抽象主题角色：真实主题和代理主题的共同接口；
2.提供一个真实主题角色：定义了代理角色所代表的真实对象；
3.提供一个代理主题角色：含有对真实主题角色的引用；
*/

class AbstractObj
{
public:
	virtual void BuyTicket() = 0;
};
class User : public AbstractObj
{
public:
	void BuyTicket()override
	{
		cout << "用户买票" << endl;
	}
};
class XiCheng : public AbstractObj
{
public:
	XiCheng(AbstractObj* pBase)
	{
		_pBase = pBase;
	}
	void BuyTicket()override
	{
		cout << "携程买票" << endl;
	}
private:
	AbstractObj* _pBase;
};
int main(void)
{
	AbstractObj* pbase = new User;
	pbase->BuyTicket(); //用户买票
	XiCheng* pProxy = new XiCheng(pbase);
	pProxy->BuyTicket(); //代理购票
	return 0;
}

//代理案例2
#include <iostream>
using namespace std;
//抽象主题类
class AbstractSubject
{
public:
	virtual void request() = 0;
};
//具体主题类
class ConcreteSubject : public AbstractSubject
{
public:
	void request()override
	{
		std::cout << "真实主题类请求" << endl;
	}
};
//代理类
class Proxy : public AbstractSubject
{
private:
	ConcreteSubject* realSubject; //这个是具体类
public:
	Proxy()
	{
		realSubject = new ConcreteSubject();
	}
	~Proxy()
	{
		delete realSubject;
	}
	void request()override
	{
		//在调用真实主题类的请求之前或者之后，可以进行一些额外的操作
		std::cout << "代理类的请求" << endl;
		realSubject->request();
	}
};

int main(void)
{
	Proxy proxy; //创建代理对象
	proxy.request(); //调用代理对象的请求，间接的调用了真实主题类的请求;
	return 0;
}

5）decorate-装饰器模式

#include <iostream>
#include<string>

using namespace std;

/*
提供一个抽象组件类：抽象被装饰者的行为
提供一个或多个具体组件类：被装饰者的具体行为实现
提供一个抽象装饰器类：
提供一个具体的装饰器类：为具体组件附加责任；
*/
//抽象组件类
class AbstractCompent
{
public:
	virtual void show() = 0;
	string _pStr;
};
//具体组件类
class Girl : public AbstractCompent
{
public:
	Girl()
	{
		_pStr = "啥也没穿的女孩子";
	}
	virtual void show()override
	{
		cout << _pStr << endl;
	}
};
//抽象装饰器类
class AbstractDecorate : public AbstractCompent
{
public:
	virtual void show() = 0;
protected:
	AbstractCompent* _pBase;
};
//具体装饰器类(超短裙)
class MiniSkirt : public AbstractDecorate
{
public:
	MiniSkirt(AbstractCompent* pbase)
	{
		_pBase = pbase;
	}
	void show(void)override
	{
		this->_pStr = this->_pBase->_pStr + " 超短裙";
		cout << _pStr << endl;
	}
};
//具体装饰器类(黑丝)
class BlackSilk : public AbstractDecorate
{
public:
	BlackSilk(AbstractCompent* pbase)
	{
		_pBase = pbase;
	}
	void show(void)override
	{
		this->_pStr = this->_pBase->_pStr + " 黑丝";
		cout << _pStr << endl;
	}
};

int main(void)
{
	//啥也没穿
	Girl* pG = new Girl;
	pG->show();
	//穿超短裙
	MiniSkirt* pM = new MiniSkirt(pG);  //装饰的是主体(pG)组件
	pM->show();
	//穿黑丝
	BlackSilk* pB = new BlackSilk(pG);  //装饰的是主体(pG)组件
	pB->show();
	//穿超短裙和黑丝
	BlackSilk* pB1 = new BlackSilk(pM); //装饰的是非主体(pM)组件
	pB1->show();
	return 0;
}

6）adapter-适配器模式

1）对象做适配
#include <iostream>
#include<string>
using namespace std;

//电源插座
class ThreeOutlet
{
public:
	void ThreeOutletCharge()
	{
		cout << "开始三插头充电" << endl;
	}
};

class AbstractTwoOutlet
{
public:
	virtual void TwoOutletcharge() = 0;
};

class TwoOutlet : public AbstractTwoOutlet
{
public:
	virtual void TwoOutletcharge()override
	{
		cout << "客户需要两插头充电............" << endl;
	}
};
//对象做适配
class OutletAdapterObject : public AbstractTwoOutlet
{
public:
	OutletAdapterObject(ThreeOutlet* pout)
	{
		this->_pOut = pout;
	}
	virtual void TwoOutletcharge()
	{
		convertor();
		_pOut->ThreeOutletCharge();
	}
	void convertor()
	{
		cout << "三插头转换为两插头" << endl;
	}
protected:
	ThreeOutlet* _pOut;
};
int main(void)
{
	ThreeOutlet* pThree = new ThreeOutlet;
	pThree->ThreeOutletCharge();
	AbstractTwoOutlet* pTwo = new OutletAdapterObject(pThree);
	pTwo->TwoOutletcharge();
	return 0;
}


2）类做适配(采用多继承方式)
#include <iostream>
#include<string>
using namespace std;

//电源插座
class ThreeOutlet
{
public:
	void ThreeOutletCharge()
	{
		cout << "开始三插头充电" << endl;
	}
};

class AbstractTwoOutlet
{
public:
	virtual void TwoOutletcharge() = 0;
};

class TwoOutlet : public AbstractTwoOutlet
{
public:
	virtual void TwoOutletcharge()override
	{
		cout << "客户需要两插头充电............" << endl;
	}
};
//针对类做适配
class OutletAdapterClass : public AbstractTwoOutlet,public ThreeOutlet
{
public:
	void TwoOutletcharge()
	{
		convertor();
		ThreeOutletCharge();
	}
	void convertor()
	{
		cout << "三插头转换为两插头" << endl;
	}
protected:
	ThreeOutlet* _pOut;
};
int main(void)
{
	ThreeOutlet* pThree = new ThreeOutlet;
	pThree->ThreeOutletCharge();
	AbstractTwoOutlet* pTwo = new OutletAdapterClass;
	pTwo->TwoOutletcharge();
	return 0;
}

7）bridge-桥接模式

#include <iostream>
#include<string>
using namespace std;

class AbstractColor
{
public:
	virtual void FillColor() = 0;
};
class Red : public AbstractColor
{
public:
	Red(): _colorType("red") {}
	void FillColor()
	{
		cout << "填充颜色:" << _colorType << endl;
	}
private:
	string _colorType;
};
class Blue : public AbstractColor
{
public:
	Blue() : _colorType("Blue") {}
	void FillColor()
	{
		cout << "填充颜色:" << _colorType << endl;
	}
private:
	string _colorType;
};

class AbstractShape
{
public:
	virtual void ShowShape() = 0;
	virtual void SetColor(AbstractColor* color) = 0;
protected:
	virtual void DrawShape() = 0;
	virtual void DrawColor() = 0;
	AbstractColor* _color;
};
class Circle : public AbstractShape
{
public:
	Circle() : _shapeType("circle") {}
	void ShowShape()override
	{
		DrawShape();
		DrawColor();
	}
	void SetColor(AbstractColor* color)override
	{
		this->_color = color;
	}
private:
	virtual void DrawShape()override
	{
		cout << "绘制: " << _shapeType << endl;
	}
	virtual void DrawColor()override
	{
		this->_color->FillColor();
	}
	string _shapeType;
};
class Rect : public AbstractShape
{
public:
	Rect():_shapeType("rect"){}
	void ShowShape()override
	{
		DrawShape();
		DrawColor();
	}
	void SetColor(AbstractColor* color)override
	{
		this->_color = color;
	}
private:
	virtual void DrawShape()override
	{
		cout << "绘制: " << _shapeType << endl;
	}
	virtual void DrawColor()override
	{
		this->_color->FillColor();
	}
	string _shapeType;
};
int main(void)
{
	cout << "绘制红色的圆" << endl;
	AbstractShape* shape = new Circle;
	shape->SetColor(new Red);
	shape->ShowShape(); //红色的圆
	delete shape;
	cout << endl;
	cout << "绘制蓝色的矩形" << endl;
	AbstractShape* rect = new Rect;
	rect->SetColor(new Blue);
	rect->ShowShape(); //蓝色的矩形
	delete rect;
	return 0;
}

8）facade-外观者模式

#include<iostream>
#include<string>

using namespace std;
//功能提供者类,包括CsyntaxParse,CMidCode,CAssemblyCode,CLinkFile；
class CsyntaxParse
{
public:
	void syntaxParse()
	{
		cout << "语法分析中..." << endl;
	}
};
class CMidCode
{
public:
	void MidCode()
	{
		cout << "生成中间文件代码中..." << endl;
	}
};
class CAssemblyCode
{
public:
	void AssemblyCode()
	{
		cout << "生成汇编代码中..." << endl;
	}
};
class CLinkFile
{
public:
	void LinkFile()
	{
		cout << "连接文件,生成可执行程序......" << endl;
	}
};

class Facade
{
public:
	void Build() //做了一些表面工作
	{
		CsyntaxParse p;
		CMidCode m;
		CAssemblyCode a;
		CLinkFile c;
		p.syntaxParse();
		m.MidCode();
		a.AssemblyCode();
		c.LinkFile();
		cout << "程序运行。。。" << endl;
	}
};
//对客户来说，只使用外观者类即可；
int main(void)
{
	Facade obj; //上帝对象
	obj.Build();
	return 0;
}

9）flyweight-享元模式

/**
 * 享元设计
 *
 *享元：就是共享元素的意思；
 * 目的: 通过共享多个对象之间的公共状态而不保存每个对象中的所有数据，以将更多的对象放入可用的RAM中
 */
#include<iostream>
#include<string>
#include<unordered_map>

struct SharedState
{
    std::string brand_;
    std::string model_;
    std::string color_;

    SharedState(const std::string& brand, const std::string& model, const std::string& color)
        : brand_(brand), model_(model), color_(color)
    {
    }

    friend std::ostream& operator<<(std::ostream& os, const SharedState& ss)
    {
        return os << "[ " << ss.brand_ << " , " << ss.model_ << " , " << ss.color_ << " ]";
    }
};

struct UniqueState
{
    std::string owner_;
    std::string plates_;

    UniqueState(const std::string& owner, const std::string& plates)
        : owner_(owner), plates_(plates)
    {
    }

    friend std::ostream& operator<<(std::ostream& os, const UniqueState& us)
    {
        return os << "[ " << us.owner_ << " , " << us.plates_ << " ]";
    }
};

/**
 * Flyweight存储属于多个实际业务实体的公共状态部分(也称为内在状态)。
 * 通过成员函数的参数接受状态的其余部分(外部状态，每个实体都是惟一的)。
 */
class Flyweight
{
private:
    SharedState* shared_state_;

public:
    Flyweight(const SharedState* shared_state) : shared_state_(new SharedState(*shared_state))
    {
    }
    Flyweight(const Flyweight& other) : shared_state_(new SharedState(*other.shared_state_))
    {
    }
    ~Flyweight()
    {
        delete shared_state_;
    }
    SharedState* shared_state() const
    {
        return shared_state_;
    }
    void Operation(const UniqueState& unique_state) const
    {
        std::cout << "Flyweight: Displaying shared (" << *shared_state_ << ") and unique (" << unique_state << ") state.\n";
    }
};
/**
 * Flyweight Factory创建和管理Flyweight对象，确保flyweight的用法和样例:当客户请求享元时，
 * 工厂要么返回一个现有实例（如果有的话），要么创建一个新实例。
 */
class FlyweightFactory
{
    /**
     * @var Flyweight[]
     */
private:
    std::unordered_map<std::string, Flyweight> flyweights_;
    /**
     * 返回对应状态的享元的键名。
     */
    std::string GetKey(const SharedState& ss) const
    {
        return ss.brand_ + "_" + ss.model_ + "_" + ss.color_;
    }

public:
    FlyweightFactory(std::initializer_list<SharedState> share_states)
    {
        for (const SharedState& ss : share_states)
        {
            this->flyweights_.insert(std::make_pair<std::string, Flyweight>(this->GetKey(ss), Flyweight(&ss)));
        }
    }

    /**
     * 返回具有给定状态的Flyweight或创建一个新Flyweight。
     */
    Flyweight GetFlyweight(const SharedState& shared_state)
    {
        std::string key = this->GetKey(shared_state);
        if (this->flyweights_.find(key) == this->flyweights_.end())
        {
            std::cout << "FlyweightFactory: Can't find a flyweight, creating new one.\n";
            this->flyweights_.insert(std::make_pair(key, Flyweight(&shared_state)));
        }
        else
        {
            std::cout << "FlyweightFactory: Reusing existing flyweight.\n";
        }
        return this->flyweights_.at(key);
    }
    void ListFlyweights() const
    {
        size_t count = this->flyweights_.size();
        std::cout << "\nFlyweightFactory: I have " << count << " flyweights:\n";
        for (std::pair<std::string, Flyweight> pair : this->flyweights_)
        {
            std::cout << pair.first << "\n";
        }
    }
};

// ...
void AddCarToPoliceDatabase(
    FlyweightFactory& ff, const std::string& plates, const std::string& owner,
    const std::string& brand, const std::string& model, const std::string& color)
{
    std::cout << "\nClient: Adding a car to database.\n";
    const Flyweight& flyweight = ff.GetFlyweight({ brand, model, color });
    // 客户端代码存储或计算外部状态并将其传递给享元对象的成员函数。
    flyweight.Operation({ owner, plates });
}

/**
 * 客户端代码通常在应用程序的初始化阶段创建一堆预先填充的权重值。
 */
int main()
{
    FlyweightFactory* factory = new FlyweightFactory({ {"Chevrolet", "Camaro2018", "pink"}, {"Mercedes Benz", "C300", "black"}, {"Mercedes Benz", "C500", "red"}, {"BMW", "M5", "red"}, {"BMW", "X6", "white"} });
    factory->ListFlyweights();

    AddCarToPoliceDatabase(*factory,
        "CL234IR",
        "James Doe",
        "BMW",
        "M5",
        "red");

    AddCarToPoliceDatabase(*factory,
        "CL234IR",
        "James Doe",
        "BMW",
        "X1",
        "red");
    factory->ListFlyweights();
    delete factory;

    return 0;
}

10）composite-组合模式

#include<iostream>
#include<string>
#include<list>

using namespace std;

class Root
{
public:
	virtual void display(void) = 0;
	virtual void add(Root* file) = 0;
	virtual void remove(Root* file) = 0;
	virtual list<Root*> getchild() = 0;
};

class File : public Root
{
public:
	File(string name):_name(name){}
	virtual void display(void)override { cout << _name << endl; }
	virtual void add(Root* file)override {}
	virtual void remove(Root* file)override {}
	virtual list<Root*> getchild()override
	{
		return _list;
	}
protected:
	string _name;
	list<Root*>_list;
};

class Floder : public Root
{
private:
	list<Root*> _list;
	string _name;
public:
	Floder(string name) :_name(name) {}
	virtual void display(void)override { cout << _name << endl; }
	virtual void add(Root* file)override 
	{
		_list.push_back(file);
	}
	virtual void remove(Root* file)override
	{
		_list.push_back(file);
	}
	virtual list<Root*> getchild()override
	{
		return _list;
	}
};
//统一一个接口
void ShowTree(Root* file, int level)
{
	list<Root*> root;
	int i = 0;
	for (int i = 0; i < level; i++)
	{
		cout << "--";
	}
	file->display();
	root = file->getchild();
	if (!root.empty())
	{
		for (auto e : root)
		{
			if (e->getchild().empty())
			{
				for (int i = 0; i <= level; i++)
				{
					cout << "--";
				}
				e->display();
			}
			else
			{
				ShowTree(e, level + 1);
			}
		}
	}
}

int main(void)
{
	Floder* root = new Floder("C:");
	Floder* d1 = new Floder("dir1");
	File* f1 = new File("t1.txt");

	Floder* d2 = new Floder("dir2");
	File* f2 = new File("t2.txt");

	root->add(d1);
	root->add(d2);
	d1->add(f1);
	d2->add(f2);
	ShowTree(root, 0);
	return 0;
}

11）templateMethod-模板方法模式

#include<iostream>
#include<string>
using namespace std;

class Makeobject
{
public:
	virtual void Makehead() = 0;
	virtual void Makebody() = 0;
	virtual void Garb() = 0;
	void Make()
	{
		Makehead();
		Makebody();
		Garb(); //服装
	}
};
class MakeGirl : public Makeobject
{
public:
	virtual void Makehead()
	{
		cout << "刘亦菲的头" << ",";
	}
	virtual void Makebody()
	{
		cout << "杨梅的身材" << ",";
	}
	virtual void Garb()
	{
		cout << "穿古装" << endl;
	}
};

class MakeBoy : public Makeobject
{
public:
	virtual void Makehead()
	{
		cout << "胡哥的头" << ",";
	}
	virtual void Makebody()
	{
		cout << "姜小二身材" << ",";
	}
	virtual void Garb()
	{
		cout << "穿西装---" << endl;
	}
};

int main(void)
{
	Makeobject* pobj = new MakeGirl;
	pobj->Make();
	delete pobj;
	pobj = new MakeBoy;
	pobj->Make();
	delete pobj;
	return 0;
}

12）Command-命令模式

#include<iostream>
#include<vector>
#include<string>
using namespace std;
//命令模式：服务员点菜及厨师做菜为案例
//定义厨师类
class Cook
{
public:
	void MakeVegetable()
	{
		cout << "蔬菜沙拉一份" << endl;
	}
	void MakeSteak()
	{
		cout << "牛排一份" << endl;
	}
	void UnVegetable()
	{
		cout << "蔬菜沙拉不要了" << endl;
	}
	void UnSteak()
	{
		cout << "牛排不要了" << endl;
	}
};
//抽象命令类
class Command
{
public:
	Command(Cook* cook = nullptr) : _cook(cook){}
	virtual void ExecuteCommand() = 0;
	virtual void UnExecuteCommand() = 0;
protected:
	Cook* _cook;
};
//具体命令类(做蔬菜沙拉)
class ConcreteVegetableCommand : public Command
{
public:
	ConcreteVegetableCommand(Cook* cook) : Command(cook){} //子类初始化父类
	void ExecuteCommand()override
	{
		_cook->MakeVegetable();
	}
	void UnExecuteCommand()override
	{
		_cook->UnVegetable();
	}
};
//具体命令类(做牛排)
class ConcreteSteakCommand : public Command
{
public:
	ConcreteSteakCommand(Cook* cook) : Command(cook) {} //子类初始化父类
	void ExecuteCommand()override
	{
		_cook->MakeSteak();
	}
	void UnExecuteCommand()override
	{
		_cook->UnSteak();
	}
};
//客户点菜
class Order
{
public:
	void setOrder(Command* cmd)
	{
		_cmdQueue.push_back(cmd);
		cout << "点一道菜" << endl;
	}
	void unOrder(Command* cmd)
	{
		_cmdQueue.pop_back(); //这里可以用查找功能，删除具体的命令，目前没有实现
		cout << "不要一道菜" << endl;
	}
	void Notify()
	{
		for (auto e : _cmdQueue)
		{
			e->ExecuteCommand();
		}
	}
private:
	vector<Command*> _cmdQueue;
};
int main(void)
{
	Cook* pcook = new Cook;
	Command* pvegetable = new ConcreteVegetableCommand(pcook);
	Command* pSteak = new ConcreteSteakCommand(pcook);
	Order* porder = new Order;
	//订单推送到命令队列
	porder->setOrder(pvegetable);
	porder->setOrder(pSteak);
	porder->Notify();
	cout << endl;
	//中途可以不要一道菜，如把牛排推掉
	porder->unOrder(pSteak);
	porder->Notify();
	cout << endl;
	//中途又加上一道菜，如把牛排推掉
	porder->setOrder(pSteak);
	porder->Notify();
	return 0;
}

/*
输出结果：
点一道菜
点一道菜
蔬菜沙拉一份
牛排一份

不要一道菜
蔬菜沙拉一份

点一道菜
蔬菜沙拉一份
牛排一份
*/

13）reposiblitychain-责任链模式

#include<iostream>
#include<string>
using namespace std;
//抽象一个处理的类
class Handler
{
public:
	Handler(): _pNext(nullptr){}
	//转接下一位
	void SetNextHandler(Handler* pnext)
	{
		this->_pNext = pnext;
	}
	//具体请求
	virtual void HandlerRequest(int days) = 0;
protected:
	Handler* _pNext;
};
//以下三个类为具体处理着
class Director:public Handler
{
public:
	virtual void HandlerRequest(int days)override
	{
		cout << "主管回复:";
		if (days <= 1)
		{
			cout << "主管同意请假" << endl;
		}
		else
		{
			cout <<"请假太长，找经理请假" << endl;
			_pNext->HandlerRequest(days);
		}
	}
};
class Manager :public Handler
{
public:
	virtual void HandlerRequest(int days)override
	{
		cout << "经理回复:";
		if (days <= 3)
		{
			cout << "经理同意请假" << endl;
		}
		else
		{
			cout << "请假太长，找老板请假" << endl;
			_pNext->HandlerRequest(days);
		}
	}
};
class Boss :public Handler
{
public:
	virtual void HandlerRequest(int days)override
	{
		cout << "老板回复:";
		if (days <= 7)
		{
			cout << "老板同意请假" << endl;
		}
		else
		{
			cout << "请假太长，不予批准!" << endl;
		}
	}
};

int main(void)
{
	//组装链
	Handler* pdirector = new Director;
	Handler* pmanager = new Manager;
	Handler* pboss = new Boss;
	pdirector->SetNextHandler(pmanager);
	pmanager->SetNextHandler(pboss);
	//开始测试请假
	cout << "请假1天结果......" << endl;
	pdirector->HandlerRequest(1);
	cout << "请假2天结果......" << endl;
	pdirector->HandlerRequest(2);
	cout << "请假8天结果......" << endl;
	pdirector->HandlerRequest(8);
	delete pdirector;
	delete pmanager;
	delete pboss;
	return 0;
}

文章来源:https://blog.csdn.net/qq_30143193/article/details/134849299
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