Question

CAsyncSocket的OnSend有什么用

Answer 1

如果成功发送的话，返回发送的字节数目， 所以，一般在onSend里写(msdn上的) void CMyAsyncSocket ::OnSend(int nErrorCode){while (m_nBytesSent < m_nBytesBufferSize){int dwBytes; if ((dwBytes = Send((LPCTSTR)m_sendBuffer + m_nBytesSent, m_nBytesBufferSize - m_nBytesSent)) == SOCKET_ERROR){if (GetLastError() == WSAEWOULDBLOCK) break;else{TCHAR szError[256]; wsprintf(szError, "Server Socket failed to send: %d ", GetLastError());Close();AfxMessageBox (szError);}}else{m_nBytesSent += dwBytes;}}if (m_nBytesSent == m_nBytesBufferSize){m_nBytesSent = m_nBytesBufferSize = 0; m_sendBuffer = " ";}CAsyncSocket::OnSend(nErrorCode);} 然后要发送的时候，把数据copy 到m_sendBuffer中，然后调一下AsyncSelect( FD_WRITE );触发onsend 但是OnSend应该是WinSock的内部发送缓冲区可用时，系统激发的消息， 还有就是，除了用AsyncSelect(FD_WRITE); 看来只能这样，不过总觉得MFC对OnSend的定义很模糊。