单例模式实现解释,有Helper类

Question

#pragma once
#include "pch.h"
#include "framework.h"

//单例模式
class CServerSocket
{
public:
    static CServerSocket* getInstance()
    {
        if(m_instance == nullptr)
        {
            m_instance = new CServerSocket();
        }
        return  m_instance;
    }
    bool InitSocket()
    {
        
        if (m_sock == -1) return false;

        sockaddr_in serv_adr;

        memset(&serv_adr, 0, sizeof(serv_adr));

        serv_adr.sin_family = AF_INET;
        serv_adr.sin_addr.S_un.S_addr = INADDR_ANY;
        serv_adr.sin_port = htons(8888);

        //绑定
        if (bind(m_sock, (sockaddr*)&serv_adr, sizeof(sockaddr_in) == -1)) return false;
        //TODO: 返回值

        if( listen(m_sock, 1) == -1) return false;
        return true;
        
    }

    bool AcceptClient()
    {
        sockaddr_in client_adr;
        int cli_sz = sizeof(client_adr);
        m_client = accept(m_sock, (sockaddr*)&client_adr, &cli_sz);
        if (m_client == -1) return  false;
        return true;
        
    }

    int DealCommand()
    {
        char buffer[1024];
        while(true)
        {
            int len = recv(m_client, buffer, sizeof(buffer), 0);
            if(len <= 0 )
            {
                return -1;
            }
            //TODO: 处理命令
        }
    }

    bool Send(const char* pData,size_t nSize)
    {
        return  send(m_client, pData, nSize, 0) > 0;
        



        
    }

    

    

    

    CServerSocket& operator=(const CServerSocket& ss) = delete;
    CServerSocket(const CServerSocket&) = delete;
private:
    SOCKET m_sock;
    SOCKET m_client;
    
    CServerSocket():m_client(INVALID_SOCKET)
    {    
        
        if(InitSockEnv() == FALSE)
        {
            MessageBox(NULL, _T("无法初始化套接字环境,请检查网络设置"), _T("初始化错误"), MB_OK | MB_ICONERROR);
            exit(0);
        }
        m_sock = socket(PF_INET, SOCK_STREAM, 0);
    };
    ~CServerSocket()
    {
        closesocket(m_sock);
        WSACleanup();
    };

    BOOL InitSockEnv()
    {

        WSADATA data;
        if(WSAStartup(MAKEWORD(1, 1), &data) != 0)
        {
            return  FALSE;
        }
        return TRUE;
        //TODO: 返回值处理
    }

    static  CServerSocket* m_instance;
    static  void releaseInstance()
    {
        if(m_instance != NULL)
        {
            CServerSocket* tmp = m_instance;
            m_instance  = NULL;
            delete tmp;
        }
    }
    
    class CHelper
    {
    public:
        CHelper()
        {
            CServerSocket::getInstance();
        }
        ~CHelper()
        {
            CServerSocket::releaseInstance();
        }
    };
    static CHelper m_helper;
};

extern CServerSocket server;

#include "pch.h"
#include "ServerSocket.h"

CServerSocket* CServerSocket::m_instance = NULL;
CServerSocket::CHelper CServerSocket::m_helper;
CServerSocket* pserver = CServerSocket::getInstance();

能解释一下CHelper类的意义吗 和调用原理吗

Answer 1

单例模式就是只有一个实例，意义就是减少了对象的创建和销毁成本，提升性能。