【设计模式】简单工厂模式

一、简单工厂模式

以汽车厂生产为例子：

工厂角色：（汽车厂）一个静态公有成员方法负责生产符合要求的产品；
抽象产品：是一个抽象类，其派生类有各种各样的产品；
具体产品：汽车car、公交车bus

对应的代码：
SimpleFactory.h

#ifndef SIMPLEFACTORY_H
#define SIMPLEFACTORY_H
#include <iostream>
#include <string>
using namespace std;
//抽象产品类
class Products
{
public:
	virtual void product() = 0;
};

//具体产品
class car : public Products
{
public:
	virtual void product()
	{
		cout << "create car" << endl;
	}
};

class bus : public Products
{
public:
	virtual void product()
	{
		std::cout << "create bus" << std::endl;
	}
};

//工厂类
class Factory
{
public:
	//静态
	static Products* create_product(const string& p_name)
	{
		Products* p = NULL;
		if(p_name == "car")
		{
			p = new car();
		}
		else if (p_name == "bus")
		{
			p = new bus();
		}

		return p;
	}
};

#endif

client.cpp

#include "SimpleFactory.h"
//客户端
int main()
{
	Products* pcar = Factory::create_product("car");
	pcar->product();

	//释放资源
	delete pcar;

	Products* pbus = Factory::create_product("bus");
	pbus->product();

	//释放资源
	delete pbus;
	
	return 0;
}

在这里插入图片描述

二、使用unique_ptr的优化

SimpleFactory.h


#ifndef SIMPLEFACTORY_H
#define SIMPLEFACTORY_H
#include <iostream>
#include <string>
#include <memory>
using namespace std;
//抽象产品类
class Products
{
public:
	virtual void product() = 0;
};

//具体产品
class car : public Products
{
public:
	virtual void product()
	{
		cout << "create car" << endl;
	}
};

class bus : public Products
{
public:
	virtual void product()
	{
		std::cout << "create bus" << std::endl;
	}
};

//工厂类
class Factory
{
public:
	//静态
	static unique_ptr<Products> create_product(const string& p_name)
	{
		
		if(p_name == "car")
		{
			return unique_ptr<Products>(new car());
		}
		else if (p_name == "bus")
		{
			return unique_ptr<Products>(new bus());
		}
		//没有匹配NULL
		return unique_ptr<Products>();
	}
};

#endif

client.cpp

#include "SimpleFactory.h"
//客户端
int main()
{
	unique_ptr<Products> upcar = Factory::create_product("car");
	upcar->product();

	unique_ptr<Products> upbus = Factory::create_product("bus");
	upbus->product();

	return 0;
}