简单工厂模式属于类的创建型模式，适合用来对大量具有共同接口的类进行实例化，它可以推迟到运行的时候才动态决定要创建哪个类的实例，而不是在编译时就必须知道要实例化哪个类。

python:

#!/usr/bin/env python# -*- coding: utf-8 -*-class Circle(object):	def draw(self):		print 'draw circle'class Rectangle(object):	def draw(self):		print 'draw Rectangle'class ShapeFactory(object):	def create(self, shape):		if shape == 'Circle':			return Circle()		elif shape == 'Rectangle':			return Rectangle()		else:			return Nonefac = ShapeFactory()obj = fac.create('Circle')obj.draw()

c++:

#include <iostream>#include <string.h>using namespace std;class Shape{public:	virtual void draw(){}};class Circle : public Shape{public:	void draw()	{		cout << "draw circle" << endl;	}};class Rectangle : public Shape{public:	void draw()	{		cout << "draw Rectangle" << endl;	}};class ShapeFactory{public:	static Shape* create(const char *opt)	{		if (opt == NULL)			return NULL;		if (!strcmp(opt, "Circle"))			return new Circle();		else if (!strcmp(opt, "Rectangle"))			return new Rectangle();		else 			return NULL;	}};int main(){	Shape *obj = ShapeFactory::create("Rectangle");		if (obj)		obj->draw();		return 0;}

python设计模式 之 简单工厂模式