设计模式-工厂模式

工厂模式

本文以下内容为芒果参考菜鸟教程-工厂模式，实现了工厂模式的c++版本以及c#版本，关于工厂模式更多的介绍可以前往菜鸟教程学习。

注：图片来源菜鸟教程

c++实现

// Copyright https://mangoroom.cn
// License(MIT)
// Author:mango
// This is factory_patter.h

#ifndef FACTORY_PATTERN_H
#define FACTORY_PATTERN_H

#include<iostream>
#include<memory>

namespace dsignpattern
{
    // 1. ch:创建一个接口 | en: Create an interface
    class Shape
    {
    public:
        virtual void Draw() = 0;
    };

    // 2. ch:创建实现接口的实体类 | en: Create an entity class that implements an interface
    class Rectangle : public Shape
    {
    public:
        void Draw() override
        {
            std::cout << "Inside Rectangle::draw() method." << std::endl;
        }
    };

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

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

    // 3. ch:创建一个工厂，生成基于给定信息的实体类的对象 | en: Create an factory to generate objects for entity classes based on a given information
    class ShapeFactory
    {
    public:
        // ch: 使用 GetShape 函数获取形状类型的对象 | en: To get an object of a shape type using the GetShape function
        std::unique_ptr<Shape> GetShape(std::string shape_type)
        {
            if (shape_type.empty())
            {
                return nullptr;
            }
            else if (shape_type == "CIRClE")
            {
                return std::unique_ptr<Shape>(new Circle());
            }
            else if (shape_type == "RECTANGLE")
            {
                return std::unique_ptr<Shape>(new Rectangle());
            }
            else if (shape_type == "SQUARE")
            {
                return std::unique_ptr<Shape>(new Square());
            }
            else
            {
                return nullptr;
            }
        }
    };

    // 4. ch: 使用该工厂，通过传递类型信息来获取实体类的对象。 | en: Use the factory to get objects for the entity class by passing type information.
    void FactoryPatternDemo();
}

#endif // FACTORY_PATTERN_H

// Copyright https://mangoroom.cn
// License(MIT)
// Author:mango
// This is factory_pattern.cpp

#include"factory_pattern.h"

using namespace dsignpattern;

// 4. ch: 使用该工厂，通过传递类型信息来获取实体类的对象。 | en: Use the factory to get objects for the entity class by passing type information.
void dsignpattern::FactoryPatternDemo()
{

    std::unique_ptr<ShapeFactory> shape_factory(new ShapeFactory());

    // ch: 获取 Circle 的对象，并调用它的 Draw函数 | en: Gets the object of the Circle and calls its Draw method
    std::unique_ptr<Shape> cirle(shape_factory->GetShape("CIRClE"));
    cirle->Draw();

    // ch: 获取 Rectangle的对象， 并调用它的 Draw函数 | en: Gets the object of the Rectangle and calls its method
    std::unique_ptr<Shape> rectangle(shape_factory->GetShape("RECTANGLE"));
    rectangle->Draw();

    // ch: 获取 Square的对象， 并调用它的Draw函数 | en: Gets the object of the Square and calls its method
    std::unique_ptr<Shape> square(shape_factory->GetShape("SQUARE"));
    square->Draw();
}

运行结果

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

c#实现

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

// Copyright https://mangoroom.cn
// License(MIT)
// Author:mango
// DesignPattern: FactoryPatternDemo
namespace DesignPattern
{
    // 1. ch:创建一个接口 | en: Create an interface
    public interface Shape
    {
        void Draw();
    }

    // 2. ch:创建实现接口的实体类 | en: Create an entity class that implements an interface

    public class Rectangle : Shape
    {
        public void Draw()
        {
            Console.WriteLine("Inside Rectangle::draw() method.");
        }
    }

    public class Square : Shape
    {
        public void Draw()
        {
            Console.WriteLine("Inside Square ::draw() method.");
        }
    }

    public class Circle : Shape
    {
        public void Draw()
        {
            Console.WriteLine("Inside Circle ::draw() method.");
        }
    }


    // 3. ch:创建一个工厂，生成基于给定信息的实体类的对象 | en: Create an factory to generate objects for entity classes based on a given information
    public class ShapeFactory
    {
        // ch: 使用 GetShape 函数获取形状类型的对象 | en: To get an object of a shape type using the GetShape function
        public Shape GetShape(string shapeType)
        {
            if(shapeType == null)
            {
                return null;
            }

            if (shapeType.Equals("CIRCLE"))
            {
                return new Circle();
            }
            else if (shapeType.Equals("RECTANGLE"))
            {
                return new Rectangle();
            }
            else if (shapeType.Equals("SQUARE"))
            {
                return new Square();
            }
            return null;
        }
    }

    public class FactoryPatternDemo
    {
        public static void FactoryPatternRun()
        {
             ShapeFactory shapeFactory = new ShapeFactory();
 
            // ch: 获取 Circle 的对象，并调用它的 Draw函数 | en: Gets the object of the Circle and calls its Draw method
            Shape circle = shapeFactory.GetShape("CIRCLE");
            circle.Draw();

            // ch: 获取 Rectangle的对象， 并调用它的 Draw函数 | en: Gets the object of the Rectangle and calls its method
            Shape rectangle = shapeFactory.GetShape("RECTANGLE");
            rectangle.Draw();

            // ch: 获取 Square的对象， 并调用它的Draw函数 | en: Gets the object of the Square and calls its method
            Shape square = shapeFactory.GetShape("SQUARE");
            square.Draw();
        }
    }
}

运行结果

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