SetRegistryKey的作用

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SetRegistryKey导致CWinApp::WriteProfileInt等操作注册表而不是INI文件

这样配置就在注册表中

否则配置文件在c:windows/下，如果写入了详细路径，则在指定路径下

在利用mfc框架的时候，在App应用类的InitInstance()函数中，初始化时总有一个 SetRegistryKey("字符串XXX")，不知道究竟有何用处，这天仔细查看了一下，发现如果你使用注册表，则它为你提供了很便利的方法，当然如果不使用系统注册表，这句可以注释掉。

以下是我在网上找到的一些资料：

SetRegistryKeyCauses application settings to be stored in the registry instead of .INI files.

SetRegistryKey 这个函数功能是设置MFC程序的注册表访问键，并把读写 ini 文件的成员函数映射到读写注册表。只要调用一下 SetRegistryKey 并指定注册表键值，那么下面6个成员函数，就被映射到进行注册表读取了~

WriteProfileBinaryWrites binary data to an entry in the application's .INI file.WriteProfileIntWrites an integer to an entry in the application's .INI file.WriteProfileStringWrites a string to an entry in the application's .INI file.
GetProfileBinaryRetrieves binary data from an entry in the application's .INI file.GetProfileIntRetrieves an integer from an entry in the application's .INI file.GetProfileStringRetrieves a string from an entry in the application's .INI file.
MSDN上面写上面6个函数是写到INI文件的。所以俺就忽略了其访问注册表的功能。无意中看了其MFC实现才有所了解。

例子如下：
SetRegistryKey(_T("boli's app")); //这里是准备在注册表HKEY_CURRENT_USER\\software 下面生成一个boli's app 分支~为什么说是准备呢？因为如果不调用相关函数，如上面提到的6个函数，它是不会真正读写注册表的。具体本文最最下面的MFC实现摘录。
CString strUserName,strPassword;
WriteProfileString("LogInfo","UserName",strUserName); //向注册表HKEY_CURRENT_USER\\software\\boli's app\\LogInfo\\分支下写入 UserName 字符串行键值~
WriteProfileString("LogInfo","Password",strPassword);//同上~

strUserName = GetProfileString("LogInfo","UserName");// 这里是读取HKEY_CURRENT_USER\\software\\boli's app\\LogInfo\\分支下的 UserName 字符串键值到 strUserName~
strPassword = GetProfileString("LogInfo","Password");

如果不是在CWinApp 派生的类中读写注册表，可以直接用：
strUserName = theApp.GetProfileString("LogInfo","UserName");
strPassword = theApp.GetProfileString("LogInfo","Password");
或
strUserName = AfxGetApp()->GetProfileString("LogInfo","UserName");
条条大路通罗马。

下列是mfc实现的代码：

////////////////////////////////////////////////////////////////////////////
// CWinApp Settings Helpers

#ifdef AFX_INIT_SEG
#pragma code_seg(AFX_INIT_SEG)
#endif

void CWinApp::SetRegistryKey(LPCTSTR lpszRegistryKey)
{
ASSERT(m_pszRegistryKey == NULL);
ASSERT(lpszRegistryKey != NULL);
ASSERT(m_pszAppName != NULL);

BOOL bEnable = AfxEnableMemoryTracking(FALSE);
free((void*)m_pszRegistryKey);
m_pszRegistryKey = _tcsdup(lpszRegistryKey);
free((void*)m_pszProfileName);
m_pszProfileName = _tcsdup(m_pszAppName);
AfxEnableMemoryTracking(bEnable);
}

void CWinApp::SetRegistryKey(UINT nIDRegistryKey)
{
ASSERT(m_pszRegistryKey == NULL);

TCHAR szRegistryKey[256];
VERIFY(AfxLoadString(nIDRegistryKey, szRegistryKey));
SetRegistryKey(szRegistryKey);
}

// returns key for HKEY_CURRENT_USER\"Software"\RegistryKey\ProfileName
// creating it if it doesn't exist
// responsibility of the caller to call RegCloseKey() on the returned HKEY
HKEY CWinApp::GetAppRegistryKey()
{
ASSERT(m_pszRegistryKey != NULL);
ASSERT(m_pszProfileName != NULL);

HKEY hAppKey = NULL;
HKEY hSoftKey = NULL;
HKEY hCompanyKey = NULL;
if (RegOpenKeyEx(HKEY_CURRENT_USER, _T("software"), 0, KEY_WRITE|KEY_READ,
   &hSoftKey) == ERROR_SUCCESS)
{
   DWORD dw;
   if (RegCreateKeyEx(hSoftKey, m_pszRegistryKey, 0, REG_NONE,
    REG_OPTION_NON_VOLATILE, KEY_WRITE|KEY_READ, NULL,
    &hCompanyKey, &dw) == ERROR_SUCCESS)
   {
    RegCreateKeyEx(hCompanyKey, m_pszProfileName, 0, REG_NONE,
     REG_OPTION_NON_VOLATILE, KEY_WRITE|KEY_READ, NULL,
     &hAppKey, &dw);
   }
}
if (hSoftKey != NULL)
   RegCloseKey(hSoftKey);
if (hCompanyKey != NULL)
   RegCloseKey(hCompanyKey);

return hAppKey;
}

// returns key for:
// HKEY_CURRENT_USER\"Software"\RegistryKey\AppName\lpszSection
// creating it if it doesn't exist.
// responsibility of the caller to call RegCloseKey() on the returned HKEY
HKEY CWinApp::GetSectionKey(LPCTSTR lpszSection)
{
ASSERT(lpszSection != NULL);

HKEY hSectionKey = NULL;
HKEY hAppKey = GetAppRegistryKey();
if (hAppKey == NULL)
return NULL;

DWORD dw;
RegCreateKeyEx(hAppKey, lpszSection, 0, REG_NONE,
REG_OPTION_NON_VOLATILE, KEY_WRITE|KEY_READ, NULL,
&hSectionKey, &dw);
RegCloseKey(hAppKey);
return hSectionKey;
}

UINT CWinApp::GetProfileInt(LPCTSTR lpszSection, LPCTSTR lpszEntry,
int nDefault)
{
ASSERT(lpszSection != NULL);
ASSERT(lpszEntry != NULL);
if (m_pszRegistryKey != NULL) // use registry
{
   HKEY hSecKey = GetSectionKey(lpszSection);
   if (hSecKey == NULL)
    return nDefault;
   DWORD dwValue;
   DWORD dwType;
   DWORD dwCount = sizeof(DWORD);
   LONG lResult = RegQueryValueEx(hSecKey, (LPTSTR)lpszEntry, NULL, &dwType,
    (LPBYTE)&dwValue, &dwCount);
   RegCloseKey(hSecKey);
   if (lResult == ERROR_SUCCESS)
   {
    ASSERT(dwType == REG_DWORD);
    ASSERT(dwCount == sizeof(dwValue));
    return (UINT)dwValue;
   }
   return nDefault;
}
else
{
   ASSERT(m_pszProfileName != NULL);
   return ::GetPrivateProfileInt(lpszSection, lpszEntry, nDefault,
    m_pszProfileName);
}
}

CString CWinApp::GetProfileString(LPCTSTR lpszSection, LPCTSTR lpszEntry,
LPCTSTR lpszDefault)
{
ASSERT(lpszSection != NULL);
ASSERT(lpszEntry != NULL);
if (m_pszRegistryKey != NULL)
{
   HKEY hSecKey = GetSectionKey(lpszSection);
   if (hSecKey == NULL)
    return lpszDefault;
   CString strValue;
   DWORD dwType, dwCount;
   LONG lResult = RegQueryValueEx(hSecKey, (LPTSTR)lpszEntry, NULL, &dwType,
    NULL, &dwCount);
   if (lResult == ERROR_SUCCESS)
   {
    ASSERT(dwType == REG_SZ);
    lResult = RegQueryValueEx(hSecKey, (LPTSTR)lpszEntry, NULL, &dwType,
     (LPBYTE)strValue.GetBuffer(dwCount/sizeof(TCHAR)), &dwCount);
    strValue.ReleaseBuffer();
   }
   RegCloseKey(hSecKey);
   if (lResult == ERROR_SUCCESS)
   {
    ASSERT(dwType == REG_SZ);
    return strValue;
   }
   return lpszDefault;
}
else
{
   ASSERT(m_pszProfileName != NULL);

   if (lpszDefault == NULL)
    lpszDefault = _T(""); // don't pass in NULL
   TCHAR szT[4096];
   DWORD dw = ::GetPrivateProfileString(lpszSection, lpszEntry,
    lpszDefault, szT, _countof(szT), m_pszProfileName);
   ASSERT(dw < 4095);
   return szT;
}
}

BOOL CWinApp::GetProfileBinary(LPCTSTR lpszSection, LPCTSTR lpszEntry,
BYTE** ppData, UINT* pBytes)
{
ASSERT(lpszSection != NULL);
ASSERT(lpszEntry != NULL);
ASSERT(ppData != NULL);
ASSERT(pBytes != NULL);
*ppData = NULL;
*pBytes = 0;
if (m_pszRegistryKey != NULL)
{
   HKEY hSecKey = GetSectionKey(lpszSection);
   if (hSecKey == NULL)
    return FALSE;

   DWORD dwType, dwCount;
   LONG lResult = RegQueryValueEx(hSecKey, (LPTSTR)lpszEntry, NULL, &dwType,
    NULL, &dwCount);
   *pBytes = dwCount;
   if (lResult == ERROR_SUCCESS)
   {
    ASSERT(dwType == REG_BINARY);
    *ppData = new BYTE[*pBytes];
    lResult = RegQueryValueEx(hSecKey, (LPTSTR)lpszEntry, NULL, &dwType,
     *ppData, &dwCount);
   }
   RegCloseKey(hSecKey);
   if (lResult == ERROR_SUCCESS)
   {
    ASSERT(dwType == REG_BINARY);
    return TRUE;
   }
   else
   {
    delete [] *ppData;
    *ppData = NULL;
   }
   return FALSE;
}
else
{
   ASSERT(m_pszProfileName != NULL);

   CString str = GetProfileString(lpszSection, lpszEntry, NULL);
   if (str.IsEmpty())
    return FALSE;
   ASSERT(str.GetLength()%2 == 0);
   INT_PTR nLen = str.GetLength();
   *pBytes = UINT(nLen)/2;
   *ppData = new BYTE[*pBytes];
   for (int i=0;i<nLen;i+=2)
   {
    (*ppData)[i/2] = (BYTE)
     (((str[i+1] - 'A') << 4) + (str[i] - 'A'));
   }
   return TRUE;
}
}

#ifdef AFX_CORE3_SEG
#pragma code_seg(AFX_CORE3_SEG)
#endif

BOOL CWinApp::WriteProfileInt(LPCTSTR lpszSection, LPCTSTR lpszEntry,
int nValue)
{
ASSERT(lpszSection != NULL);
ASSERT(lpszEntry != NULL);
if (m_pszRegistryKey != NULL)
{
   HKEY hSecKey = GetSectionKey(lpszSection);
   if (hSecKey == NULL)
    return FALSE;
   LONG lResult = RegSetValueEx(hSecKey, lpszEntry, NULL, REG_DWORD,
    (LPBYTE)&nValue, sizeof(nValue));
   RegCloseKey(hSecKey);
   return lResult == ERROR_SUCCESS;
}
else
{
   ASSERT(m_pszProfileName != NULL);

   TCHAR szT[16];
   wsprintf(szT, _T("%d"), nValue);
   return ::WritePrivateProfileString(lpszSection, lpszEntry, szT,
    m_pszProfileName);
}
}

BOOL CWinApp::WriteProfileString(LPCTSTR lpszSection, LPCTSTR lpszEntry,
    LPCTSTR lpszValue)
{
ASSERT(lpszSection != NULL);
if (m_pszRegistryKey != NULL)
{
   LONG lResult;
   if (lpszEntry == NULL) //delete whole section
   {
    HKEY hAppKey = GetAppRegistryKey();
    if (hAppKey == NULL)
     return FALSE;
    lResult = ::RegDeleteKey(hAppKey, lpszSection);
    RegCloseKey(hAppKey);
   }
   else if (lpszValue == NULL)
   {
    HKEY hSecKey = GetSectionKey(lpszSection);
    if (hSecKey == NULL)
     return FALSE;
    // necessary to cast away const below
    lResult = ::RegDeleteValue(hSecKey, (LPTSTR)lpszEntry);
    RegCloseKey(hSecKey);
   }
   else
   {
    HKEY hSecKey = GetSectionKey(lpszSection);
    if (hSecKey == NULL)
     return FALSE;
    lResult = RegSetValueEx(hSecKey, lpszEntry, NULL, REG_SZ,
     (LPBYTE)lpszValue, (lstrlen(lpszValue)+1)*sizeof(TCHAR));
    RegCloseKey(hSecKey);
   }
   return lResult == ERROR_SUCCESS;
}
else
{
   ASSERT(m_pszProfileName != NULL);
   ASSERT(lstrlen(m_pszProfileName) < 4095); // can't read in bigger
   return ::WritePrivateProfileString(lpszSection, lpszEntry, lpszValue,
    m_pszProfileName);
}
}

BOOL CWinApp::WriteProfileBinary(LPCTSTR lpszSection, LPCTSTR lpszEntry,
LPBYTE pData, UINT nBytes)
{
ASSERT(lpszSection != NULL);
if (m_pszRegistryKey != NULL)
{
   LONG lResult;
   HKEY hSecKey = GetSectionKey(lpszSection);
   if (hSecKey == NULL)
    return FALSE;
   lResult = RegSetValueEx(hSecKey, lpszEntry, NULL, REG_BINARY,
    pData, nBytes);
   RegCloseKey(hSecKey);
   return lResult == ERROR_SUCCESS;
}

// convert to string and write out
LPTSTR lpsz = new TCHAR[nBytes*2+1];
UINT i;
for (i = 0; i < nBytes; i++)
{
lpsz[i*2] = (TCHAR)((pData[i] & 0x0F) + 'A'); //low nibble
lpsz[i*2+1] = (TCHAR)(((pData[i] >> 4) & 0x0F) + 'A'); //high nibble
}
lpsz[i*2] = 0;

ASSERT(m_pszProfileName != NULL);

BOOL bResult = WriteProfileString(lpszSection, lpszEntry, lpsz);
delete[] lpsz;
return bResult;
}

/////////////////////////////////////////////////////////////////////////////