【正文】 ut of it when I have processed all of the // data available. Be careful with this approach and // be sure your loop will exit. // My reasons for this are not as clear in this sample // as it is in my production code, but I have found this // solutiion to be the most efficient way to do this. if ( == 0) { // break out when all bytes have been read break。 LeaveCriticalSection(amp。dwError, amp。portm_csCommunicationSync)。 for (。 DWORD BytesRead = 0。 BOOL bResult = TRUE。 Message Length: %d\n, BytesSent, strlen((char*)portm_szWriteBuffer))。 // deal with the error code if (!bResult) { portProcessErrorMessage(GetOverlappedResults() in WriteFile())。 // Wait flag LeaveCriticalSection(amp。portm_ov, // Overlapped structure amp。 } } // end if(bWrite) if (!bWrite) { bWrite = TRUE。 } } } else { LeaveCriticalSection(amp。 break。 switch (dwError) { case ERROR_IO_PENDING: { // continue to GetOverlappedResults() BytesSent = 0。portm_ov)。 bResult = WriteFile(portm_hComm, // Handle to COMM Port portm_szWriteBuffer, // Pointer to message buffer in calling finction strlen((char*)portm_szWriteBuffer), // Length of message to send amp。 port = 0。portm_csCommunicationSync)。 ResetEvent(portm_hWriteEvent)。 BOOL bResult = TRUE。 return TRUE。m_csCommunicationSync)。 // flush the port PurgeComm(m_hComm, PURGE_RXCLEAR | PURGE_TXCLEAR | PURGE_RXABORT | PURGE_TXABORT)。 delete [] szPort。 } else ProcessErrorMessage(SetCommMask())。 } else ProcessErrorMessage(BuildCommDCB())。m_dcb)) 。 // set RTS bit high! if (BuildCommDCB(szBaud, amp。m_CommTimeouts)) { if (SetCommMask(m_hComm, dwCommEvents)) { if (GetCommState(m_hComm, amp。 = 1000。 = 1000。 } // set the timeout values = 1000。 delete [] szBaud。 // get a handle to the port m_hComm = CreateFile(szPort, // munication port string (COMX) GENERIC_READ | GENERIC_WRITE, // read/write types 0, // m devices must be opened with exclusive access NULL, // no security attributes OPEN_EXISTING, // m devices must use OPEN_EXISTING FILE_FLAG_OVERLAPPED, // Async I/O 0)。 } // prepare port strings sprintf(szPort, COM%d, portnr)。 // if the port is already opened: close it if (m_hComm != NULL) { CloseHandle(m_hComm)。 // now it critical! EnterCriticalSection(amp。 char *szPort = new char[50]。 m_dwCommEvents = dwCommEvents。 m_nPortNr = portnr。 if (m_szWriteBuffer != NULL) delete [] m_szWriteBuffer。m_csCommunicationSync)。 m_hEventArray[2] = m_hWriteEvent。 // initialize the event objects m_hEventArray[0] = m_hShutdownEvent。 if (m_hShutdownEvent != NULL) ResetEvent(m_hShutdownEvent)。if (m_hWriteEvent != NULL) ResetEvent(m_hWriteEvent)。 } // create events if ( != NULL) ResetEvent()。 } while (m_bThreadAlive)。 assert(pPortOwner != NULL)。amp。}。 DWORD m_dwCommEvents。// misc UINT m_nPortNr。 DCB m_dcb。 // structures OVERLAPPED m_ov。 HANDLE m_hWriteEvent。// handles HANDLE m_hShutdownEvent。// synchronisation objects CRITICAL_SECTION m_csCommunicationSync。 static void WriteChar(CSerialPort* port)。 static UINT CommThread(LPVOID pParam)。void WriteToPort(char* string)。 DWORD GetCommEvents()。 BOOL StopMonitoring()。 // start/stop m watching BOOL StartMonitoring()。E39。 virtual ~CSerialPort()。IN_TIME汽車進(jìn)入的時間OUT_TIME汽車駛出的時間PAY_AMOUNT司機(jī)所交的費(fèi)用CAR_IMAGE汽車進(jìn)入時的圖片SQL語句為：CREATE TABLE [dbo].[TAB_HISTORY_CARD] ( [CARD_ID] [varchar] (50) NULL , [IN_TIME] [datetime] NULL , [OUT_TIME] [datetime] NULL , [PAY_AMOUNT] [money] NULL , [CAR_IMAGE] [image] NULL ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]（主要配置ODBC數(shù)據(jù)庫）打開配置對話框，配置名為DSN_VicAly，驅(qū)程為SQL Server的數(shù)據(jù)源：并改變默認(rèn)數(shù)據(jù)庫名為VicAly:第五章重點(diǎn)功能實(shí)現(xiàn)及其代碼 在本系統(tǒng)中實(shí)現(xiàn)串口通信的類為CSerialPort，它是一個開發(fā)源碼的類，作者為Remon Spekreijse. 類的定義：【代碼示例】CSerialPort類定義（串口通信類）//********************************************************* FILENAME **PURPOSE This class can read, write and watch one serial port.** It sends messages to its owner when something happends on the port** The class creates a thread for reading and writing so the main** program is not blocked.** AUTHOR Remon Spekreijse*/ifndef __SERIALPORT_H__define __SERIALPORT_H__define WM_COMM_BREAK_DETECTED WM_USER+1 // A break was detected on input.define WM_COMM_CTS_DETECTED WM_USER+2 // The CTS (cleartosend) signal changed state. define WM_COMM_DSR_DETECTED WM_USER+3 // The DSR (datasetready) signal changed state. define WM_COMM_ERR_DETECTED WM_USER+4 // A linestatus error occurred. Linestatus errors are CE_FRAME, CE_OVERRUN, and CE_RXPARITY. define WM_COMM_RING_DETECTED WM_USER+5 // A ring indicator was detected. define WM_COMM_RLSD_DETECTED WM_USER+6 // The RLSD (receivelinesignaldetect) signal changed state. define WM_COMM_RXCHAR WM_USER+7 // A character was received and placed in the input buffer. define WM_COMM_RXFLAG_DETECTED WM_USER+8 // The event character was received and placed in the input buffer. define WM_COMM_TXEMPTY_DETECTED WM_USER+9 // The last character in the output buffer was sent. class CSerialPort{ public: BOOL ClearRXBuffer()。SQL語句為：CREATE TABLE [dbo].[TAB_COUNTTIME] ( [CARD_ID] [varchar] (50) NOT NULL , [IN_TIME] [datetime] NULL , [CAR_IMAGE] [image] NULL )系統(tǒng)的需求中要保存每個車輛進(jìn)入車場的歷史記錄，包括進(jìn)入時所持卡的號碼、進(jìn)入時間、出門時間、收費(fèi)情況和當(dāng)時進(jìn)門時的圖像。IN_TIME是汽車進(jìn)入時間。在正式工作之前，管理員或者是收款