将CStdioFile类扩展,读取UNICODE文本文件

huangyhg

最近因为要读取SQL脚本文件，用CStdioFile来读取脚本文件，却在程序调试时读取不了文件。
后来看了一下文本文件格式，竟然是UNICODE格式的，原来在导出ＳＱＬ脚本的时候，选项默认的是UNICODE格式。为了同时支持ANSI和UNICODE两种格式，在Codeproject站点上找到了CStdioFileEx类的代码，但在调试运行过程中发现，在生成UNICODE版本的执行文件时，运行没有错误，但在非UNICODE版本中却出现错误，原来在代码中此部分没有考虑文件读到末尾的情况，经修改，CStdioFileEx类就可以正常使用了，在读取文本文件时，自动识别ANSI和UNICODE两种格式。
实现头文件如下：


#define nUNICODE_BOM 0xFEFF // Unicode "byte order mark" which goes at start of file
#define sNEWLINE _T("\r\n") // New line characters
#define sDEFAULT_UNICODE_FILLER_CHAR "#" // Filler char used when no conversion from Unicode to local code page is possible

class CStdioFileEx: public CStdioFile
{
public:
CStdioFileEx();
CStdioFileEx( LPCTSTR lpszFileName, UINT nOpenFlags );

virtual BOOL Open( LPCTSTR lpszFileName, UINT nOpenFlags, CFileException* pError = NULL );
virtual BOOL ReadString(CString& rString);
virtual void WriteString( LPCTSTR lpsz );
bool IsFileUnicodeText() { return m_bIsUnicodeText; }
unsigned long GetCharCount();

// Additional flag to allow Unicode text writing
static const UINT modeWriteUnicode;

// static utility functions

// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::GetUnicodeStringFromMultiByteString()
//
// --------------------------------------------------------------------------------------------
// Returns: bool
// Parameters: char * szMultiByteString (IN) Multi-byte input string
// wchar_t* szUnicodeString (OUT) Unicode output string
// short nUnicodeBufferSize (IN) Size of Unicode output buffer
// UINT nCodePage (IN) Code page used to perform conversion
// Default = -1 (Get local code page).
//
// Purpose: Gets a Unicode string from a MultiByte string.
// Notes: None.
// Exceptions: None.
//
static bool GetUnicodeStringFromMultiByteString(char * szMultiByteString,wchar_t* szUnicodeString,
short nUnicodeBufferSize,UINT nCodePage=-1);

// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::GetMultiByteStringFromUnicodeString()
//
// --------------------------------------------------------------------------------------------
// Returns: BOOL
// Parameters: wchar_t * szUnicodeString (IN) Unicode input string
// char* szMultiByteString (OUT) Multibyte output string
// short nMultiByteBufferSize (IN) Multibyte buffer size
// UINT nCodePage (IN) Code page used to perform conversion
// Default = -1 (Get local code page).
//
// Purpose: Gets a MultiByte string from a Unicode string.
// Notes: .
// Exceptions: None.
//
static BOOL GetMultiByteStringFromUnicodeString(wchar_t * szUnicodeString,char* szMultiByteString,
short nMultiByteBufferSize,UINT nCodePage=-1);


// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::IsFileUnicode()
//
// --------------------------------------------------------------------------------------------
// Returns: bool
// Parameters: const CString& sFilePath
//
// Purpose: Determines whether a file is Unicode by reading the first character and detecting
// whether it's the Unicode byte marker.
// Notes: None.
// Exceptions: None.
//
static bool IsFileUnicode(const CString& sFilePath);


protected:
UINT ProcessFlags(const CString& sFilePath, UINT& nOpenFlags);

bool m_bIsUnicodeText;
UINT m_nFlags;
};



实现文件如下：


/*static*/ const UINT CStdioFileEx::modeWriteUnicode = 0x20000; // Add this flag to write in Unicode

CStdioFileEx::CStdioFileEx(): CStdioFile()
{
m_bIsUnicodeText = false;
}

CStdioFileEx::CStdioFileEx(LPCTSTR lpszFileName,UINT nOpenFlags)
:CStdioFile(lpszFileName, ProcessFlags(lpszFileName, nOpenFlags))
{
}

BOOL CStdioFileEx::Open(LPCTSTR lpszFileName,UINT nOpenFlags,CFileException* pError /*=NULL*/)
{
// Process any Unicode stuff
ProcessFlags(lpszFileName, nOpenFlags);

return CStdioFile::Open(lpszFileName, nOpenFlags, pError);
}

BOOL CStdioFileEx::ReadString(CString& rString)
{
const int nMAX_LINE_CHARS = 4096;
BOOL bReadData;
LPTSTR lpsz;
int nLen = 0; //, nMultiByteBufferLength = 0, nChars = 0;
CString sTemp;
wchar_t* pszUnicodeString = NULL;
char * pszMultiByteString= NULL;

// If at position 0, discard byte-order mark before reading
if (!m_pStream || (GetPosition() == 0 && m_bIsUnicodeText))
{
wchar_t cDummy;
// Read(&cDummy, sizeof(_TCHAR));
Read(&cDummy, sizeof(wchar_t));
}

// If compiled for Unicode
#ifdef _UNICODE
// Do standard stuff -- both ANSI and Unicode cases seem to work OK
bReadData = CStdioFile::ReadString(rString);
#else

if (!m_bIsUnicodeText)
{
// Do standard stuff -- read ANSI in ANSI
bReadData = CStdioFile::ReadString(rString);
}
else
{
pszUnicodeString = new wchar_t[nMAX_LINE_CHARS];
pszMultiByteString= new char[nMAX_LINE_CHARS];

// Read as Unicode, convert to ANSI

if(fgetws(pszUnicodeString, nMAX_LINE_CHARS, m_pStream)==NULL)
{
bReadData=FALSE;
}
else
{
bReadData=TRUE;
if (GetMultiByteStringFromUnicodeString(pszUnicodeString, pszMultiByteString, nMAX_LINE_CHARS))
{
rString = (CString)pszMultiByteString;
}

if (pszUnicodeString)
{
delete pszUnicodeString;
}

if (pszMultiByteString)
{
delete pszMultiByteString;
}
}
}
#endif

// Then remove end-of-line character if in Unicode text mode
if (bReadData)
{
// Copied from FileTxt.cpp but adapted to Unicode and then adapted for end-of-line being just '\r'.
nLen = rString.GetLength();
if (nLen > 1 && rString.Mid(nLen-2) == sNEWLINE)
{
rString.GetBufferSetLength(nLen-2);
}
else
{
lpsz = rString.GetBuffer(0);
if (nLen != 0 && (lpsz[nLen-1] == _T('\r') || lpsz[nLen-1] == _T('\n')))
{
rString.GetBufferSetLength(nLen-1);
}
}
}

return bReadData;
}

// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::WriteString()
//
// --------------------------------------------------------------------------------------------
// Returns: void
// Parameters: LPCTSTR lpsz
//
// Purpose: Writes string to file either in Unicode or multibyte, depending on whether the caller specified the
// CStdioFileEx::modeWriteUnicode flag. Override of base class function.
// Notes: If writing in Unicode we need to:
// a) Write the Byte-order-mark at the beginning of the file
// b) Write all strings in byte-mode
// - If we were compiled in Unicode, we need to convert Unicode to multibyte if
// we want to write in multibyte
// - If we were compiled in multi-byte, we need to convert multibyte to Unicode if
// we want to write in Unicode.
// Exceptions: None.
//
void CStdioFileEx::WriteString(LPCTSTR lpsz)
{
// If writing Unicode and at the start of the file, need to write byte mark
if (m_nFlags & CStdioFileEx::modeWriteUnicode)
{
// If at position 0, write byte-order mark before writing anything else
if (!m_pStream || GetPosition() == 0)
{
wchar_t cBOM = (wchar_t)nUNICODE_BOM;
CFile::Write(&cBOM, sizeof(wchar_t));
}
}

// If compiled in Unicode...
#ifdef _UNICODE

// If writing Unicode, no conversion needed
if (m_nFlags & CStdioFileEx::modeWriteUnicode)
{
// Write in byte mode
CFile::Write(lpsz, lstrlen(lpsz) * sizeof(wchar_t));
}
// Else if we don't want to write Unicode, need to convert
else
{
int nChars = lstrlen(lpsz) + 1; // Why plus 1? Because yes
int nBufferSize = nChars * sizeof(char);
wchar_t* pszUnicodeString = new wchar_t[nChars];
char * pszMultiByteString= new char[nChars];

// Copy string to Unicode buffer
lstrcpy(pszUnicodeString, lpsz);

// Get multibyte string
if (GetMultiByteStringFromUnicodeString(pszUnicodeString, pszMultiByteString, nBufferSize, GetACP()))
{
// Do standard write
CFile::Write((const void*)pszMultiByteString, lstrlen(lpsz));
}

if (pszUnicodeString && pszMultiByteString)
{
delete [] pszUnicodeString;
delete [] pszMultiByteString;
}
}
// Else if *not* compiled in Unicode
#else
// If writing Unicode, need to convert
if (m_nFlags & CStdioFileEx::modeWriteUnicode)
{
int nChars = lstrlen(lpsz) + 1; // Why plus 1? Because yes
int nBufferSize = nChars * sizeof(wchar_t);
wchar_t* pszUnicodeString = new wchar_t[nChars];
char * pszMultiByteString= new char[nChars];

// Copy string to multibyte buffer
lstrcpy(pszMultiByteString, lpsz);

if (GetUnicodeStringFromMultiByteString(pszMultiByteString, pszUnicodeString, nBufferSize, GetACP()))
{
// Write in byte mode
CFile::Write(pszUnicodeString, lstrlen(lpsz) * sizeof(wchar_t));
}
else
{
ASSERT(false);
}

if (pszUnicodeString && pszMultiByteString)
{
delete [] pszUnicodeString;
delete [] pszMultiByteString;
}
}
// Else if we don't want to write Unicode, no conversion needed
else
{
// Do standard stuff
CStdioFile::WriteString(lpsz);
}

#endif
}

UINT CStdioFileEx:rocessFlags(const CString& sFilePath, UINT& nOpenFlags)
{
m_bIsUnicodeText = false;

// If we have writeUnicode we must have write or writeRead as well
#ifdef _DEBUG
if (nOpenFlags & CStdioFileEx::modeWriteUnicode)
{
ASSERT(nOpenFlags & CFile::modeWrite || nOpenFlags & CFile::modeReadWrite);
}
#endif

// If reading in text mode and not creating...
if (nOpenFlags & CFile::typeText && !(m_nFlags & CFile::modeCreate) && !(m_nFlags & CFile::modeWrite ))
{
m_bIsUnicodeText = IsFileUnicode(sFilePath);

// If it's Unicode, switch to binary mode
if (m_bIsUnicodeText)
{
nOpenFlags ^= CFile::typeText;
nOpenFlags |= CFile::typeBinary;
}
}

m_nFlags = nOpenFlags;

return nOpenFlags;
}

// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::IsFileUnicode()
//
// --------------------------------------------------------------------------------------------
// Returns: bool
// Parameters: const CString& sFilePath
//
// Purpose: Determines whether a file is Unicode by reading the first character and detecting
// whether it's the Unicode byte marker.
// Notes: None.
// Exceptions: None.
//
/*static*/ bool CStdioFileEx::IsFileUnicode(const CString& sFilePath)
{
CFile file;
bool bIsUnicode = false;
wchar_t cFirstChar;
CFileException exFile;

// Open file in binary mode and read first character
if (file.Open(sFilePath, CFile::typeBinary | CFile::modeRead, &exFile))
{
// If byte is Unicode byte-order marker, let's say it's Unicode
if (file.Read(&cFirstChar, sizeof(wchar_t)) > 0 && cFirstChar == (wchar_t)nUNICODE_BOM)
{
bIsUnicode = true;
}

file.Close();
}
else
{
// Handle error here if you like
}

return bIsUnicode;
}

unsigned long CStdioFileEx::GetCharCount()
{
int nCharSize;
unsigned long nByteCount, nCharCount = 0;

if (m_pStream)
{
// Get size of chars in file
nCharSize = m_bIsUnicodeText ? sizeof(wchar_t): sizeof(char);

// If Unicode, remove byte order mark from count
nByteCount = (unsigned long)GetLength();

if (m_bIsUnicodeText)
{
nByteCount = nByteCount - sizeof(wchar_t);
}

// Calc chars
nCharCount = (nByteCount / nCharSize);
}

return nCharCount;
}

// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::GetUnicodeStringFromMultiByteString()
//
// --------------------------------------------------------------------------------------------
// Returns: bool
// Parameters: char * szMultiByteString (IN) Multi-byte input string
// wchar_t* szUnicodeString (OUT) Unicode outputstring
// short nUnicodeBufferSize (IN) Size of Unicode output buffer
// UINT nCodePage (IN) Code page used to perform conversion
// Default = -1 (Get local code page).
//
// Purpose: Gets a Unicode string from a MultiByte string.
// Notes: None.
// Exceptions: None.
//
bool CStdioFileEx::GetUnicodeStringFromMultiByteString(char * szMultiByteString, wchar_t* szUnicodeString, short nUnicodeBufferSize, UINT nCodePage)
{
bool bOK = true;
int nReturn = 0;
CString sErrorMsg;

if (szUnicodeString && szMultiByteString)
{
// If no code page specified, take default for system
if (nCodePage == -1)
{
nCodePage = GetACP();
}

try
{
nReturn = MultiByteToWideChar(nCodePage,MB_PRECOMPOSED,szMultiByteString,-1,szUnicodeString,nUnicodeBufferSize);

if (nReturn == 0)
{
bOK = false;
}
}
catch(...)
{
bOK = false;
}
}
else
{
bOK = false;
}

ASSERT(bOK);
return bOK;
}

// --------------------------------------------------------------------------------------------
//
// CStdioFileEx::GetMultiByteStringFromUnicodeString()
//
// --------------------------------------------------------------------------------------------
// Returns: BOOL
// Parameters: wchar_t * szUnicodeString (IN) Unicode input string
// char* szMultiByteString (OUT) Multibyte output string
// short nMultiByteBufferSize (IN) Multibyte buffer size
// UINT nCodePage (IN) Code page used to perform conversion
// Default = -1 (Get local code page).
//
// Purpose: Gets a MultiByte string from a Unicode string
// Notes: None.
// Exceptions: None.
//
BOOL CStdioFileEx::GetMultiByteStringFromUnicodeString(wchar_t * szUnicodeString, char* szMultiByteString,
short nMultiByteBufferSize, UINT nCodePage)
{
BOOL bUsedDefChar = FALSE;
BOOL bGotIt = FALSE;

if (szUnicodeString && szMultiByteString)
{
// If no code page specified, take default for system
if (nCodePage == -1)
{
nCodePage = GetACP();
}

try
{
bGotIt = WideCharToMultiByte(nCodePage, WC_COMPOSITECHECK | WC_SEPCHARS,
szUnicodeString,-1, szMultiByteString, nMultiByteBufferSize, sDEFAULT_UNICODE_FILLER_CHAR, &bUsedDefChar);
}
catch(...)
{
TRACE(_T("Controlled exception in WideCharToMultiByte!\n"));
}
}

return bGotIt;
}