建造者模式

建造者把产品细节的实现过程单独封装成类，完成产品本身和创建产品之间的解耦。每一个建造者都相对独立，因此在建造细节实现方面实现了灵活性和可扩展性。

建造者模式和工厂模式的区别：工厂模式关心把这个产品创建出来，而不关心其细节；建造者模式不仅需要把产品生产出来，还需要关心生产细节。

建造者的核心在于将建造者独立成不同的子类，以实现建造过程的灵活性和可扩展性。

示例代码

#include<iostream>
#include<string>
using namespace std;class Meal{
public:void setBurger(string str){burger = str;}void setFries(string str){fries = str;}void setDrink(string str){drink = str;}void print(){std::cout << burger << std::endl;std::cout << fries << std::endl;std::cout << drink << std::endl;}
private:string burger;string fries;string drink;
};
class MealBuilder{
public:virtual void buildBurger(){}virtual void buildFries(){}virtual void buildDrink(){}virtual Meal* getMeal(){return meal;}Meal* meal = new Meal();
};
class ChickenMealBuilder : public MealBuilder{
public:void buildBurger(){meal->setBurger("鸡肉汉堡");}void buildFries(){meal->setFries("中份薯条");}void buildDrink(){meal->setDrink("大杯果汁");}
};
class BeefBurgerMealBuilder : public MealBuilder{
public:void buildBurger(){meal->setBurger("牛肉汉堡");}void buildFries(){meal->setFries("大份薯条");}void buildDrink(){meal->setDrink("中杯可乐");}
};
class ShrimpMealBuilder : public MealBuilder{
public:void buildBurger(){meal->setBurger("虾肉汉堡");}void buildFries(){meal->setFries("小份薯条");}void buildDrink(){meal->setDrink("大杯芬达");}
};
class MealDirector{
public:void setMealBuilder(MealBuilder* mealBuilder){this->mealBuilder = mealBuilder;}Meal* getMeal(){ return mealBuilder->getMeal(); }void constructMeal(){mealBuilder->buildBurger();mealBuilder->buildFries();mealBuilder->buildDrink();}
private:MealBuilder* mealBuilder;
};
int main(){MealDirector* director = new MealDirector();director->setMealBuilder(new BeefBurgerMealBuilder());director->constructMeal();Meal* meal = director->getMeal();meal->print();
}