概念
裝飾模式又叫包裝模式。通過一種對用戶端透明的方式來擴充對象功能,是繼承關系的一個替換方案。
裝飾模式就是把要添加的附加功能分别放在單獨的類中,并讓這個類包含它要裝飾的對象,當需要執行時,用戶端就可以有選擇地、按順序地使用裝飾功能包裝對象。
類圖角色和職責
![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLiQ3chVEa0V3bT9CX5RXa2Fmcn9CXwczLcVmds92czlGZvwVP9EUTDZ0aRJkSwk0LcxGbpZ2LcBDM08CXlpXazRnbvZ2LcRlMMVDT2EWNvwFdu9mZvwVPFdFZvlzVZ9mTYR2bwNjW1x2RkZXUYpVd1kmYr50MZV3YyI2cKJDT29GRjBjUIF2LcRHelR3LcJzLctmch1mclRXY39DM3cjMxkjMxITOwYDM3EDMy8CX0Vmbu4GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.jpg)
适用于:裝飾着模式(Decorator Pattern)動态的給一個對象添加一些額外的職責。就增加功能來說,此模式比生成子類更為靈活。
案例
#include <iostream>
using namespace std;
class Car
{
public:
virtual void show() = 0;
};
class RunCar:public Car
{
public:
void run()
{
cout << "可以跑" << endl;
}
virtual void show()
{
run();
}
};
class SwimCarDirector:public Car
{
public:
SwimCarDirector(Car *p)
{
m_p = p;
}
void swim()
{
cout << "可以遊泳" << endl;
}
virtual void show()
{
m_p->show();
swim();
}
private:
Car *m_p;
};
class FlyCarDirector:public Car
{
public:
FlyCarDirector(Car *p)
{
m_p = p;
}
void fly()
{
cout << "可以飛" << endl;
}
virtual void show()
{
m_p->show();
fly();
}
private:
Car *m_p;
}
int main(void)
{
Car *runcar = NULL;
runcar = new RunCar();
runcar->show();
cout << "車開始裝飾swim" << endl;
SwimCarDirector *swimCar = new SwimCarDirector(runcar);
swimCar->show();
cout << "車開始裝飾fly" << endl;
FlyCarDirector *flyCar= new FlyCarDirector(runcar);
flyCar->show();
delete flyCar;
delete swimCar;
delete runCar;
return 0;
}