【设计模式】工厂模式的map优化

---

一、有map，无unique_ptr版本

（1）代码

Factory.h

#ifndef FACTORY_H
#define FACTORY_H
#include <iostream>
#include <string>
#include <memory>
#include <map>
using namespace std;

//有map

//抽象产品类
class Products
{
public:
	//产品方法
	virtual void productMethod() = 0;
};
//car产品类
class car : public Products
{
public:
	void productMethod()
	{
		cout << " car " << endl;
	}
};

//bus产品类
class bus : public Products
{
public:
	void productMethod()
	{
		cout << " bus " << endl;
	}
};


//抽象工厂类
class BaseFactory
{
public:
	virtual Products* create() = 0;
public:
	static map<string, BaseFactory*> fac;	// key value
	static Products* create_product(const string& name)
	{
		if (fac.find(name) != fac.end())
		{
			//fac[name]是name工厂地址
			return fac[name]->create();
		}
		else
		{
			return NULL;
		}
	}
};
//类外初始化
map<string, BaseFactory*> BaseFactory::fac;

//car工厂类
class carFactory : public BaseFactory
{
public:
	Products* create()
	{
		return new car();
	}
};

//bus工厂类
class busFactory : public BaseFactory
{
public:
	Products* create()
	{
		return new bus();
	}
};

//使用一个初始化类对BaseFactory::map<string, BaseFactory*>fac进行初始化
class Init_BaseFac
{
	static Init_BaseFac m_init;
public:
	Init_BaseFac()
	{
		BaseFactory::fac["car"] = new carFactory();
		BaseFactory::fac["bus"] = new busFactory();
	}
};

//避免使用Init_BaseFac类手动初始化
Init_BaseFac Init_BaseFac::m_init;

client.cpp

//有map,无unique_ptr
#include "Factory.h"

void fun()
{
	Products* p = BaseFactory::create_product("car");
	p->productMethod();

	p = BaseFactory::create_product("bus");
	p->productMethod();
	delete p;
}


int main()
{
	fun();
	return 0;
}

（2）结果

---

二、有map，有unqiue_ptr版本

（1）代码

Factory.h

#ifndef FACTORY_H
#define FACTORY_H
#include <iostream>
#include <string>
#include <memory>
#include <map>
using namespace std;

//有map，有unique_ptr

//抽象产品类
class Products
{
public:
	//产品方法
	virtual void productMethod() = 0;
};
//car产品类
class car : public Products
{
public:
	void productMethod()
	{
		cout << " car " << endl;
	}
};

//bus产品类
class bus : public Products
{
public:
	void productMethod()
	{
		cout << " bus " << endl;
	}
};


//抽象工厂类
class BaseFactory
{
public:
	virtual unique_ptr<Products> create() = 0;
public:
	static map<string, unique_ptr<BaseFactory>> fac;	// key value
	static unique_ptr<Products> create_product(const string& name)
	{
		if (fac.find(name) != fac.end())
		{
			//fac[name]是name工厂地址
			return fac[name]->create();
		}
		else
		{
			return NULL;
		}
	}
};
//类外初始化
map<string, unique_ptr<BaseFactory>> BaseFactory::fac;

//car工厂类
class carFactory : public BaseFactory
{
public:
	unique_ptr<Products>create()
	{
		return unique_ptr<Products>(new car());
	}
};

//bus工厂类
class busFactory : public BaseFactory
{
public:
	unique_ptr<Products>create()
	{
		return unique_ptr<Products>(new bus());
	}
};

//使用一个初始化类对BaseFactory::map<string, BaseFactory*>fac进行初始化
class Init_BaseFac
{
	static Init_BaseFac m_init;
public:
	Init_BaseFac()
	{
		BaseFactory::fac["car"] = unique_ptr<BaseFactory>(new carFactory());
		BaseFactory::fac["bus"] = unique_ptr<BaseFactory>(new busFactory());
	}
};

//避免使用Init_BaseFac类手动初始化
Init_BaseFac Init_BaseFac::m_init;

client.cpp

#include "Factory.h"

void fun()
{
	unique_ptr<Products> p = BaseFactory::create_product("car");
	p->productMethod();
	
	p = BaseFactory::create_product("bus");
	p->productMethod();
}

int main()
{
	fun();
	return 0;
}

（2）结果