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深入浅出设计模式笔记 -----Decorator

2007-10-12 22:50 369 查看

读了深入浅出设计模式Decorator篇,对于Decorator有了新的了解与认识，决定将Decorator模式实现一遍,下面用C++语言将咖啡馆的例子重现。
UML图:

/********************************************************************
created: 2007/10/12
filename: AbstractCofee.h
author: 凌剑 http://blog.csdn.net/missvip
purpose: Decorator抽象的咖啡类与抽象的修饰类
*********************************************************************/
#ifndef ABSTRACTCOFEE_H
#define ABSTRACTCOFEE_H

#include <string>
using namespace std;

class BeverageCofee
{
public:
virtual double getCost() =0;
virtual string getDescription () =0;
};

class DecoratorCofee : public BeverageCofee
{
protected:
DecoratorCofee(BeverageCofee *pBever);
BeverageCofee *pBeverage;
};

#endif

/********************************************************************
created: 2007/10/12
filename: ConcreteCofee.h
author: 凌剑 http://blog.csdn.net/missvip
purpose: Decorator具体的咖啡类与具体的修饰类
*********************************************************************/
#ifndef CONCRETECOFEE_H_H
#define CONCRETECOFEE_H_H

#include "AbstractCofee.h"

class HostBlendCofee : public BeverageCofee
{
public:
double getCost();
string getDescription();
};

class DarkHostCofee : public BeverageCofee
{
public:
double getCost();
string getDescription();
};

class Milk : public DecoratorCofee
{
public:
Milk(BeverageCofee *pBever);
double getCost();
string getDescription ();
};

class Suger : public DecoratorCofee
{
public:
Suger(BeverageCofee *pBever);
double getCost();
string getDescription ();
};

#endif

/********************************************************************
created: 2007/10/12
filename: AbstractCofee.cpp
author: 凌剑 http://blog.csdn.net/missvip
purpose: Decorator抽象的咖啡类与抽象的修饰类
*********************************************************************/
#include "AbstractCofee.h"

DecoratorCofee::DecoratorCofee(BeverageCofee *pBever):pBeverage(pBever)
{

}

/********************************************************************
created: 2007/10/12
filename: ConcreteCofee.cpp
author: 凌剑 http://blog.csdn.net/missvip
purpose: Decorator具体的咖啡类与具体的修饰类
*********************************************************************/
#include "ConcreteCofee.h"

double HostBlendCofee::getCost()
{
return 4.0;
}

string HostBlendCofee::getDescription()
{
return "HostBlend咖啡";
}

double DarkHostCofee::getCost()
{
return 5.0;
}

string DarkHostCofee::getDescription()
{
return "DarkHost咖啡";
}

Milk::Milk(BeverageCofee *pBever):DecoratorCofee(pBever)
{

}

double Milk::getCost()
{
return pBeverage->getCost()+1.5;
}

string Milk::getDescription()
{
return pBeverage->getDescription()+"+牛奶";
}

Suger::Suger(BeverageCofee *pBever):DecoratorCofee(pBever)
{

}

double Suger::getCost()
{
return pBeverage->getCost()+0.5;
}

string Suger::getDescription()
{
return pBeverage->getDescription()+"+糖";
}

/********************************************************************
created: 2007/10/12
filename: Main.cpp
author: 凌剑 http://blog.csdn.net/missvip
purpose: 客户程序测试Decorator
*********************************************************************/
#include <iostream>
#include "ConcreteCofee.h"
using namespace std;

int main()
{
BeverageCofee *OrderDarkHostCofee =new DarkHostCofee();
cout<<OrderDarkHostCofee->getDescription()<<"价格是:"<<OrderDarkHostCofee->getCost()<<endl;

//加糖后的价格
OrderDarkHostCofee =new Suger(OrderDarkHostCofee);
cout<<OrderDarkHostCofee->getDescription()<<"价格是:"<<OrderDarkHostCofee->getCost()<<endl;

//加牛奶后的价格
OrderDarkHostCofee =new Milk(OrderDarkHostCofee);
cout<<OrderDarkHostCofee->getDescription()<<"价格是:"<<OrderDarkHostCofee->getCost()<<endl;

return 0;
}

最后运行结果:

可以看到DarkHost咖啡的价格是5元
加入调料糖后的价格变成5+0.5

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