设计模式-享元模式

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已于 2023-03-31 14:17:54 修改

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分类专栏：设计模式 c++ 文章标签：设计模式

于 2016-11-09 22:34:51 首次发布

本文链接：https://blog.youkuaiyun.com/yelede2009/article/details/53106932

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本文介绍了一种用于节省内存开销的设计模式——享元模式，并通过具体实现展示了如何使用共享和非共享享元对象来减少资源消耗。代码示例涵盖了享元接口、工厂类及其实现细节。

适用情境:需要大量共享对象,以节省内存开销.

这里写图片描述

// flyweight.h
#ifndef FLYWEIGHT_H
#define FLYWEIGHT_H

class Flyweight
{
public:
    virtual void Show() = 0;
};

#endif // FLYWEIGHT_H

// sharedflyweight.h
#ifndef SHAREDFLYWEIGHT_H
#define SHAREDFLYWEIGHT_H

#include "flyweight.h"
#include <string>

class SharedFlyweight : public Flyweight
{
public:
    SharedFlyweight(std::string name);
    virtual void Show();
private:
    std::string m_name;
};

#endif // SHAREDFLYWEIGHT_H

// sharedflyweight.cpp
#include "sharedflyweight.h"
#include <iostream>

SharedFlyweight::SharedFlyweight(std::__cxx11::string name)
{
    m_name = name;
}

void SharedFlyweight::Show()
{
    std::cout << "name : " << m_name << std::endl;
}

// unsharedflyweight.h
#ifndef UNSHAREDFLYWEIGHT_H
#define UNSHAREDFLYWEIGHT_H

#include "flyweight.h"
#include <string>

class UnsharedFlyweight : public Flyweight
{
public:
    UnsharedFlyweight(std::string name);
    virtual void Show();
private:
    std::string m_name;
};

#endif // UNSHAREDFLYWEIGHT_H

// unsahredflyweight.cpp
#include "unsharedflyweight.h"
#include <iostream>

UnsharedFlyweight::UnsharedFlyweight(std::string name)
{
    m_name = name;
}

void UnsharedFlyweight::Show()
{
    std::cout << "name : " << m_name << std::endl;
}

// flyweightfactory.h
#ifndef FLYWEIGHTFACTORY_H
#define FLYWEIGHTFACTORY_H

#include "flyweight.h"
#include <vector>

class FlyweightFactory
{
public:
    std::vector<Flyweight*> m_flyweightList;
public:
    FlyweightFactory();
    Flyweight* GetFlyweight();
};

#endif // FLYWEIGHTFACTORY_H

// flyweightfactory.cpp
#include "flyweightfactory.h"
#include "sharedflyweight.h"

FlyweightFactory::FlyweightFactory()
{
    m_flyweightList.push_back(new SharedFlyweight(" shared flyweight test"));
}

Flyweight* FlyweightFactory::GetFlyweight()
{
    std::vector<Flyweight*>::iterator it = m_flyweightList.begin();
    return (*it);
}

客户端:

// main.cpp
#include <iostream>
#include "sharedflyweight.h"
#include "flyweightfactory.h"
#include "unsharedflyweight.h"

using namespace std;

int main(int argc, char *argv[])
{
    FlyweightFactory* flyweight_factory = new FlyweightFactory();
    Flyweight* shared_flyweight = flyweight_factory->GetFlyweight();

    Flyweight* unshare_flyweight = new UnsharedFlyweight("unshare flyweight");

    shared_flyweight->Show();
    unshare_flyweight->Show();

    return 0;
}