设计模式——工厂方法模式_FactoryMethod

工厂方法模式

Define an interface for creating an object, but let subclasses decide which class to instantiate Factory Method lets a class defer instantiation to subclasses.

定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化推迟到其子类

#include <iostream>
using namespace std;

class Widget {
public:
	virtual void Manufacture() = 0;  
	virtual void Destroy() = 0;
};

class Widget_A : public Widget {
public:
	void Manufacture() { cout << "我是由工厂制造出的零件A" << endl; }
	void Destroy() { cout << "我是即被工厂销毁的零件A" << endl; }
};

class Widget_B : public Widget {
public:
	void Manufactory() {cout << "我是由工厂制造出的零件B" << endl; }
	void Destroy()  { cout << "我是即被工厂销毁的零件B" << endl; }
};

class Factory {
public:
	virtual Widget* CreateWidget() = 0;
};

class Widget_AFactory : public Factory {
public:
	Widget_A* CreateWidget() { return new Widget_A(); }
};

class Widget_BFactory : public Factory {
public:
	Widget_B* CreateWidget() { return new Widget_B(); }
};

int main()
{
	Widget_AFactory* pWidget_AFactory = new Widget_AFactory();
	Widget_A* pWidget_A = pWidget_AFactory->CreateWidget();

	pWidget_A->Manufacture();
	pWidget_A->Destroy();

	delete pWidget_A;
	delete pWidget_AFactory;

	return 0;
}

工厂方法模式的扩展：

1缩小为简单工厂模式

2升级为多个工厂类

3替代单例模式

4延迟初始化