FlyWeight 享元模式-优快云博客

本文链接：https://blog.youkuaiyun.com/zhangxiaonanwin/article/details/6049360

本文介绍了一种使用C++实现享元模式的方法，通过抽象基类和具体子类演示了如何利用享元工厂来管理和复用对象，从而减少内存消耗。

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#include <cstdlib>
#include <iostream>
#include <vector>
using namespace std;
class FlyWeight
{
protected:
std::string m_name;
public:
FlyWeight(std::string str):m_name(str){}
virtual ~FlyWeight(){cout<<"FlyWeight 基类析构"<<endl;}
std::string GetName()const{return m_name;}
};
class FlyWeightConcreteA:public FlyWeight
{
public:
virtual ~FlyWeightConcreteA(){cout<<"FlyWeightConcreteA 子类析构"<<endl;}
FlyWeightConcreteA(std::string str):FlyWeight(str + "A"){}
};
class FlyWeightConcreteB:public FlyWeight
{
public:
virtual ~FlyWeightConcreteB(){cout<<"FlyWeightConcreteB 子类析构"<<endl;}
FlyWeightConcreteB(std::string str):FlyWeight(str + "B"){}
};
class FlyWeightFactory
{
protected:
vector<FlyWeight*> m_vector;
public:
virtual FlyWeight* GetFlyWeight(std::string str) = 0;
virtual ~FlyWeightFactory()
{
    cout<<"FlyWeightFactory 基类析构"<<endl;
    vector<FlyWeight*>::iterator it = m_vector.begin(),itend = m_vector.end();
    for(;it != itend; it++)
    {
      delete *it;
    }
    m_vector.clear();
}
};
class FlyWeightFactoryA:public FlyWeightFactory
{
public:
virtual ~FlyWeightFactoryA(){cout<<"FlyWeightFactoryA 子类析构"<<endl;}
virtual FlyWeight* GetFlyWeight(std::string str)
{
    vector<FlyWeight*>::iterator it = m_vector.begin(),itend = m_vector.end();
    for(;it != itend; it++)
    {
      if((*it)->GetName() == (str + "A"))return *it;
    }
    FlyWeight* pFly = new FlyWeightConcreteA(str);
    m_vector.push_back(pFly);
    return pFly;
}
};
class FlyWeightFactoryB:public FlyWeightFactory
{
public:
virtual ~FlyWeightFactoryB(){cout<<"FlyWeightFactoryB 子类析构"<<endl;}
virtual FlyWeight* GetFlyWeight(std::string str)
{
    vector<FlyWeight*>::iterator it = m_vector.begin(),itend = m_vector.end();
    for(;it != itend; it++)
    {
      if((*it)->GetName() == (str + "B"))return *it;
    }
    FlyWeight* pFly = new FlyWeightConcreteB(str);
    m_vector.push_back(pFly);
    return pFly;
}
};
void Do(FlyWeightFactory* pFac,int x,int y)
{
FlyWeight* pFly = pFac->GetFlyWeight("hello");
cout<<"数出字符串:"<<pFly->GetName()<<"在x="<<x<<",y="<<y<<endl;
pFly = pFac->GetFlyWeight("world");
cout<<"数出字符串:"<<pFly->GetName()<<"在x="<<x<<",y="<<y<<endl;
pFly = pFac->GetFlyWeight("hello");
cout<<"数出字符串:"<<pFly->GetName()<<"在x="<<x<<",y="<<y<<endl;
}
int main(int argc, char *argv[])
{
    FlyWeightFactory* oneFac = new FlyWeightFactoryA;
    cout<<"----------------"<<endl;
    Do(oneFac,10,10);
    cout<<"----------------"<<endl;
    delete oneFac;
    oneFac = new FlyWeightFactoryB;
    cout<<"----------------"<<endl;
    Do(oneFac,100,100);
    cout<<"----------------"<<endl;
    delete oneFac;
    system("PAUSE");
    return EXIT_SUCCESS;
}