化繁为简系列原创教程

红太狼 2021-11-22 21:08 272阅读 0赞

这是一个小巧的客户端套接字类，类名、函数名和变量名均采用匈牙利命名法。小写的x代表我的姓氏首字母（谢欣能），个人习惯而已，如有雷同，纯属巧合。

CxClientSocket的定义如下：

class XIOCTRL_CLASS CxClientSocket : public CxSocket
    {
    public:
        CxClientSocket();
        virtual ~CxClientSocket();
        void operator=(SOCKET s) { m_socket = s; }
    
    public:
        virtual BOOL Connect(LPCSTR lpszIPAddr, int nPort);
        virtual BOOL IsConnected();
        BOOL DisConnect();
    
        BOOL Send(LPBYTE lpbtData, DWORD dwSize);
        BOOL Recv(LPBYTE lpbtData, DWORD dwSize);
        BOOL GetRemoteHost(LPSTR lpszIPAddr);
    
    protected:
        BOOL Listen();
        void DisListen();
        static DWORD WINAPI ListenProc(LPVOID lpParam);
        void OnListen();
    
    protected:
        HANDLE m_hThreadListen;
        BOOL m_bExitThreadListen;
    };

由于这个类被封装在动态库里面，所以类名前使用了导出标志XIOCTRL\_CLASS，读者在使用时完全可以去掉。这个类的定义被放在一个包含很多类定义的头文件中，我没有单独为它写头文件，所以它的定义部分代码看上去没有上下文。

CxClientSocket的实现如下：

CxClientSocket::CxClientSocket()
        : m_hThreadListen(NULL)
        , m_bExitThreadListen(TRUE)
    {
        
    }
    
    CxClientSocket::~CxClientSocket()
    {
    
    }
    
    BOOL CxClientSocket::GetRemoteHost(LPSTR lpszIPAddr)
    {
        sockaddr_in sa = {
        0};
        int nSize = sizeof(sa);
        int iResult = getpeername(m_socket, (sockaddr*)&sa, &nSize);
        if (iResult == SOCKET_ERROR)
            return FALSE;
        else
        {
            strcpy(lpszIPAddr, inet_ntoa(sa.sin_addr));
            return TRUE;
        }
    }
    
    BOOL CxClientSocket::Listen()
    {
        if (m_hThreadListen != NULL)
            return FALSE;
    
        m_bExitThreadListen = FALSE;
        DWORD dwThreadID;
        m_hThreadListen = CreateThread(NULL, 0, ListenProc, this, 0, &dwThreadID);
        
        return (m_hThreadListen != NULL);
    }
    
    void CxClientSocket::DisListen()
    {
        if (m_hThreadListen != NULL)
        {
            m_bExitThreadListen = TRUE;
    
            WaitForSingleObject(m_hThreadListen, INFINITE);
            CloseHandle(m_hThreadListen);
            m_hThreadListen = NULL;
        }
    }
    
    DWORD WINAPI CxClientSocket::ListenProc(LPVOID lpParam)
    {
        DWORD dwID = ::GetCurrentThreadId();
        char szDebug[MAX_PATH];
        sprintf(szDebug, "The thread 0x%X(CxClientSocket::ListenProc) has entered.\n", dwID);
        OutputDebugString(szDebug);
    
        CxClientSocket* pThis = (CxClientSocket*)lpParam;
        if (pThis != NULL)
            pThis->OnListen();
        
        sprintf(szDebug, "The thread 0x%X(CxClientSocket::ListenProc) has exited.\n", dwID);
        OutputDebugString(szDebug);
    
        return 0;
    }
    
    void CxClientSocket::OnListen()
    {
        fd_set fd;
        FD_ZERO(&fd);
        FD_SET(m_socket, &fd);
        
        /*struct timeval timet;
        timet.tv_sec = 1;
        timet.tv_usec = 0;*/
        
        while (!m_bExitThreadListen)
        {
            int i = select((int)m_socket, &fd, NULL, NULL, NULL);
            if (i > 0)
            {
                if (m_wndproc != NULL)
                {
                    m_wndproc(m_msg.hwnd, m_msg.message,
                    (WPARAM)m_socket, (LPARAM)MAKELPARAM(FD_READ, 0));
                }
            }
        }
    }
    
    BOOL CxClientSocket::Connect(LPCSTR lpszIPAddr, int nPort)
    {
        DisConnect();
    
        if (m_socket == INVALID_SOCKET)
            m_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        if (m_socket == INVALID_SOCKET)
            return FALSE;
        
        sockaddr_in service = {
        0};
        service.sin_family = AF_INET;
        service.sin_addr.s_addr = inet_addr(lpszIPAddr);
        service.sin_port = htons(nPort);
    
        int iResult = connect(m_socket, (SOCKADDR*)&service, sizeof(service));
        if (iResult == SOCKET_ERROR)
        {
            DisConnect();
            DWORD dwError = WSAGetLastError();
            return FALSE;
        }
        
        long lEvent = FD_WRITE | FD_CLOSE;
        if (m_wndproc == NULL)
            lEvent |= FD_READ;
        else
            Listen();
    
        SelectEvent(lEvent);
    
        return TRUE;
    }
    
    BOOL CxClientSocket::DisConnect()
    {
        if (m_socket == INVALID_SOCKET)
            return TRUE;
    
        if (IsConnected())
        {
            int iResult = shutdown(m_socket, SD_BOTH);
            if (iResult == SOCKET_ERROR)
                return FALSE;
        }
    
        DisListen();
    
        int iResult = closesocket(m_socket);
        if (iResult == SOCKET_ERROR)
            return FALSE;
        
        m_socket = INVALID_SOCKET;
        return TRUE;
    }
    
    BOOL CxClientSocket::IsConnected()
    {
        sockaddr_in saCur = {
        0};
        int nLen = sizeof(saCur);
        int iResult = getpeername(m_socket, (SOCKADDR*)&saCur, &nLen);
        return (iResult != SOCKET_ERROR);
    }
    
    BOOL CxClientSocket::Send(LPBYTE lpbtData, DWORD dwSize)
    {
        DWORD nCount = 0, nToSend;
        int iRet;
        LPBYTE lpbtIterator;
        DWORD dwError;
    
        while (nCount != dwSize)
        {
            nToSend = dwSize - nCount;
            lpbtIterator = &lpbtData[nCount];
            iRet = send(m_socket, (const char*)lpbtIterator, nToSend, 0);
            if (iRet != SOCKET_ERROR)
                nCount += iRet;
            else // something wrong
            {
                dwError = WSAGetLastError();
                if (dwError != WSAEWOULDBLOCK)
                    break;
            }
        }
        
        return (nCount == dwSize);
    }
    
    BOOL CxClientSocket::Recv(LPBYTE lpbtData, DWORD dwSize)
    {
        DWORD nCount = 0;
        int nToReceive, iRet;
        LPBYTE lpbtIterator;
        DWORD dwError;
    
        while (nCount != dwSize)
        {
            nToReceive = dwSize - nCount;
            lpbtIterator = &lpbtData[nCount];
            iRet = recv(m_socket, (char*)lpbtIterator, nToReceive, 0);
            if (iRet != SOCKET_ERROR)
            {
                if (iRet == 0)    // disconnect by remote host
                {
                    //dwError = WSAGetLastError();    // No error
                    WSASetLastError(WSAENOTCONN);
                    break;
                }
                else
                    nCount += iRet;
            }
            else // something wrong
            {
                dwError = WSAGetLastError();
                if (dwError != WSAEWOULDBLOCK)
                    break;
            }
        }
        
        return (nCount == dwSize);
    }

这个类的实现被放在一个包含很多类实现的CPP文件中，没有单独为它写CPP文件，所以它的实现部分代码看上去没有上下文（比如头文件包含、宏定义等等）。这个类的实现部分的代码不多，总共210多行。实现了（断开）连接服务端、发送接收数据以及侦听接收缓存区数据的功能（以消息响应或回调函数的方式通知上层程序处理接收缓存区数据）。

我写的很多实用类都非常简洁，一般都没有注释，有也是中英文混搭两句，大家习惯就好。To be continued...