设计模式_结构型模式_装饰器模式

装饰器模式和代理模式很像。
代理模式是已经知道代理谁了，所以只是对委托类的访问权限进行限制，因此用户只需要访问相应的代理类就可以。装饰器模式并不知道要装饰谁，所以需要传入具体的被装饰对象进行功能的添加

目的：

增加现有类的功能，但是，增加现有类的功能还有一个方法，就是新增加一个子类
添加子类的缺点：功能虽然可以完成，但是代码中有太多的子类添加进来，相同功能的代码大多相同，代码冗余严重

代码实现

#include<iostream>
#include<mutex>
#include<memory>
#include<unordered_map>
#include<list>
using namespace std;
class Car
{
public:
	virtual void Show() = 0;
};

class Bmw:public Car
{
public:
	void Show()
	{
		cout << "这是一辆宝马汽车:有基本配置" << " ";
	}
};
class Audi :public Car
{
public:
	void Show()
	{
		cout << "这是一辆奥迪汽车:有基本配置" << " ";
	}
};
class Benz :public Car
{
public:
	void Show()
	{
		cout << "这是一辆奔驰汽车:有基本配置" << " ";
	}
};

//装饰器1:定速巡航
class ConcreateDecorator01 :public Car
{
public:
	ConcreateDecorator01(Car*p):pCar(p){}
	void Show()
	{
		pCar->Show();
		cout << "定速巡航" << " ";
	}
private:
	Car* pCar;
};

//装饰器2:自动刹车
class ConcreateDecorator02 :public Car
{
public:
	ConcreateDecorator02(Car* p) :pCar(p) {}
	void Show()
	{
		pCar->Show();
		cout << "自动刹车" << " ";
	}
private:
	Car* pCar;
};
//装饰器3:车道偏离
class ConcreateDecorator03 :public Car
{
public:
	ConcreateDecorator03(Car* p) :pCar(p) {}
	void Show()
	{
		pCar->Show();
		cout << "车道偏离" << " ";
	}
private:
	Car* pCar;
};
int main()
{
	Car* p1 = new ConcreateDecorator01(new Bmw());
	p1= new ConcreateDecorator02(p1);
	p1 = new ConcreateDecorator03(p1);
	p1->Show();
	cout << endl;

	Car* p2 = new Audi();
	p2 = new ConcreateDecorator02(p2);
	p2->Show();
	cout << endl;
	Car* p3 = new Benz();
	p3->Show();
	cout << endl;
	return 0;
}