Headfirst设计模式的C++实现——简单工厂模式(Simple Factory)

Pizza.h

 #ifndef _PIZZA_H
 #define _PIZZA_H
 #include <iostream>
 #include <string>

 class Pizza
 {
 public:
     Pizza(const std::string &type) : m_type(type) {}
     virtual ~Pizza() {}
     virtual void prepare() { std::cout << "prepare " << m_type << std::endl; }
     virtual void bake() { std::cout << "bake " << m_type << std::endl; }
     virtual void cut() { std::cout << "cut " << m_type << std::endl; }
     virtual void box() { std::cout << "box " << m_type << std::endl; }
 private:
     std::string m_type;
 };
 #endif

CheesePizza.h

 #ifndef _CHEESE_PIZZA_H
 #define _CHEESE_PIZZA_H
 #include <iostream>
 #include "Pizza.h"

 class CheesePizza : public Pizza
 {
 public:
     CheesePizza() : Pizza("cheese") {}
     ~CheesePizza() {}
 };
 #endif

GreekPizza.h

 #ifndef _GREEK_PIZZA_H
 #define _GREEK_PIZZA_H
 #include <iostream>
 #include "Pizza.h"

 class GreekPizza : public Pizza
 {
 public:
     GreekPizza() : Pizza("greek") {}
     ~GreekPizza() {}
 };

 #endif

SimplePizzaFactory.h

 #ifndef _SIMPLE_PIZZA_FACTORY
 #define _SIMPLE_PIZZA_FACTORY

 #include "CheesePizza.h"
 #include "GreekPizza.h"

 class SimplePizzaFactory
 {
 public:
     Pizza *CreatePizza(const std::string & type)
     {
         if ( "cheese" == type )
         {
             return new CheesePizza();
         }
         if ( "greek" == type )
         {
             return new GreekPizza();
         }
         return NULL;
     }
 };
 #endif

PizzaStore.h

 #ifndef _PIZZA_STORE_H
 #define _PIZZA_STORE_H
 #include "SimplePizzaFactory.h"

 class PizzaStore
 {
 private:
     SimplePizzaFactory pizza_factory;
 public:
     Pizza* OrderPizza(const std::string &type)
     {
         Pizza *p_pizza = pizza_factory.CreatePizza(type);
         if (p_pizza)
         {
             p_pizza->prepare();
             p_pizza->bake();
             p_pizza->cut();
             p_pizza->box();
         }
         return p_pizza;
     }
 };
 #endif

main.cpp

 #include "PizzaStore.h"
 int main()
 {
     PizzaStore pizza_store;
     Pizza *p_pizza = pizza_store.OrderPizza("greek");
     if ( p_pizza )
     {
         delete p_pizza;
     }
     return ;
 }