创建模式-工厂模式

工厂模式（Factory Pattern）是 Java 中最常用的设计模式之一。这种类型的设计模式属于创建型模式，它提供了一种创建对象的最佳方式。

在工厂模式中，我们在创建对象时不会对客户端暴露创建逻辑，并且是通过使用一个共同的接口来指向新创建的对象。

实现

我们将创建一个  Shape  接口和实现  Shape  接口的实体类。下一步是定义工厂类  ShapeFactory 。

FactoryPatternDemo ，我们的演示类使用  ShapeFactory  来获取  Shape  对象。它将向  ShapeFactory  传递信息（ CIRCLE / RECTANGLE / SQUARE ），以便获取它所需对象的类型。

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
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 */

/* 
 * File:   InterfaceDefineAndDraw.h
 * Author: leixiao
 *
 * Created on 2018年1月23日, 上午10:47
 */

#ifndef INTERFACEDEFINEANDDRAW_H
#define INTERFACEDEFINEANDDRAW_H


class Shape
{
public:
    virtual void draw()=0;
};

#endif /* INTERFACEDEFINEANDDRAW_H */

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

#include <iostream>
#include <string>
#include "InterfaceDefineAndDraw.h"
using namespace std;
class Rectangle:public Shape
{
    public:
        void draw()
        {
            cout << "Inside Rectangle::draw() method."<<endl;
            return ;
        }
    private:
        
    
};

class Square:public Shape
{
public :
    void draw()
    {
        cout << "Inside Square::draw() method."<<endl;
        return ;
    }
};

class Circle:public Shape
{
public :
    void draw()
    {
        cout << "Inside Circle::draw() method."<<endl;
        return ;
    }
};

class ShapeFactory
{
public:
    Shape* getShape(string type)
    {
        if(type == "Rectangle")
        {
            
            Shape *tmp = new Rectangle();
            return tmp;
        }
        else if(type == "Square")
        {
            Shape *tmp =  new Square();
            return tmp;
        }
        else if(type == "Circle")
        {
            Shape *tmp = new Circle();
            return tmp;
        }
        return NULL;
    }
};

int main()
{
    ShapeFactory *shapeFactory = new ShapeFactory();
    Shape *shapeRectangle = shapeFactory->getShape("Rectangle");
    shapeRectangle->draw();
    Shape *shapeSquare = shapeFactory->getShape("Square");
    shapeSquare->draw();
    Shape *shapeCircle = shapeFactory->getShape("Circle");
    shapeCircle->draw();
    return 0;
}

运行结果：

Inside Rectangle::draw() method.
Inside Square::draw() method.
Inside Circle::draw() method.

github：https://github.com/chujiangke/designpattern