设计模式[21]-Factory Method

Type: Creational

Factory Method: 定义一个创建对象的接口，但是让子类决定实例化哪个类。新增加一个产品的时候，只需派生一个该类型的工厂而无需修改原来的代码。每个具体工厂只负责返回一种产品类。是最典型的模板方法模式(Templete Method pattern)应用。

#include <iostream>
using namespace std;  

class Product{};  

class ConcreteProduct: public Product
{
public:
    ConcreteProduct()
    {
        cout<<"ConcreteProduct"<<endl;
    };
};  

class Creator
{
public:
    virtual Product* factoryMethod() = 0;
};  

class ConcreteCreator: public Creator
{
public:
    Product* factoryMethod()
    {
        cout<<"ConcreteCreator decide which class to instantiate"<<endl;
        return new ConcreteProduct;
    };
};  

int main()
{
    Creator* pCreator = new ConcreteCreator;
    Product* pProduct = pCreator->factoryMethod();
    system("pause");
};