15结构型模式之享元模式

概念

　　Flyweight模式也叫享元模式，是构造型模式之一，它通过与其他类似对象共享数据来减小内存占用。

角色和职责

抽象享元角色：

所有具体享元类的父类，规定一些需要实现的公共接口。

具体享元角色：

抽象享元角色的具体实现类，并实现了抽象享元角色规定的方法。

享元工厂角色：

负责创建和管理享元角色。

使用场景：

　　是以共享的方式，高效的支持大量的细粒度的对象。

案例

//相同的信息，但不是同一个人。

#include <iostream>
using namespace std;
#include "string"
#include "map"

class Person
{
public:
	Person(string name, int age, int sex)
	{
		this->name = name;
		this->age = age;
		this->sex = sex;
	}
	string getName()
	{
		return name;
	}
	int getAge()
	{
		return age;
	}
	int getSex()
	{
		return sex;
	}
protected:
	string	name;
	int		age;
	int		sex; //1男 2女
};

class Teacher : public Person
{
public:
	Teacher(string id, string name, int age, int sex) : Person(name, age, sex)
	{
		this->id = id;
	}

	string getId()
	{
		return id;
	}
	void printT()
	{
		cout << "id:" <<id << "\t" << "name:" <<name << "\t" << "age:" <<age << "\t" << "sex:" <<sex << "\t" << endl;
	}
private:
	string id;
};

class TeacherFactory
{
public:
	TeacherFactory()
	{
		m_tpool.empty();
	}
	~TeacherFactory()
	{
		//内存管理 永远是c++程序员的痛
		while (!m_tpool.empty()) //在工厂中创建老师结点，在工厂中销毁老师结点
		{
			Teacher *tmp = NULL;
			map<string, Teacher *>::iterator it = m_tpool.begin();
			tmp = it->second;
			m_tpool.erase(it);
			delete tmp;
		}
	}
	//通过Teacher的pool，来存放老师结点，在TeacherFactory中创建老师、销毁老师
	Teacher *getTeacher(string tid)
	{
		string	name;
		int		age;
		int		sex;

		Teacher *tmp = NULL;
		map<string, Teacher*>::iterator it =  m_tpool.find(tid);
		if (it == m_tpool.end())
		{
			cout << "id为: " << tid << " 的老师不存在,系统为你创建该老师，请输入以下信息" <<endl;
			cout << "请输入老师姓名：";
			cin >> name;
			cout << "请输入老师年龄：";
			cin >> age;
			cout << "请输入老师性别 1男 2女：";
			cin >> sex;
			tmp = new Teacher(tid, name, age, sex);
			m_tpool.insert(pair<string, Teacher*>(tid, tmp));
		}
		else
		{
			tmp = (it->second);
		}
		return tmp;
	}

private:
	map<string, Teacher *> m_tpool;
};

void main()
{
	/*
	Teacher *t1 = new Teacher("001", "小李", 30, 1);
	Teacher *t2 = new Teacher("002", "小张", 30, 1);
	Teacher *t3 = new Teacher("001", "小李", 30, 1);
	Teacher *t4 = new Teacher("004", "小吴", 30, 1);
	//
	cout << "t1 t3的 工号一样，但是也不是同一个人 " << endl;
	delete t1;
	delete t2;
	delete t3;
	delete t4;
	*/
	TeacherFactory *teacherFactory = new TeacherFactory;
	Teacher *t1 = teacherFactory->getTeacher("001");
	t1->printT();

	Teacher *t2 = teacherFactory->getTeacher("001");
	t2->printT();
    delete teacherFactory;
	system("pause");
	return ;
}

原文地址：https://www.cnblogs.com/gd-luojialin/p/10358004.html