Windows API封装:LoadLibrary/FreeLibrary

LoadLibrary/LoadLibraryEx用来加载DLL到自己的进程空间,使用完用FreeLibrary释放,一般使用方式如下:
HINSTANCE hInstRich = ::LoadLibrary(CRichEditCtrl::GetLibraryName());

ATLASSERT(hInstRich != NULL);

::FreeLibrary(hInstRich);
若使用过程中遇到跳转语句,即使不忘记 FreeLibrary,代码也会变得相当难看.一种优雅的封装方式如下(原理同智能指针):
class CLoadLibrary

{

public:

HINSTANCE m_hInst;

CLoadLibrary(HINSTANCE hInst = NULL) : m_hInst(hInst)

{

}

CLoadLibrary(LPCTSTR pstrFileName) : m_hInst(NULL)

{

Load(pstrFileName);

}

~CLoadLibrary()

{

Free();

}

BOOL Load(LPCTSTR pstrFileName, DWORD dwFlags = 0)

{

ATLASSERT(!::IsBadStringPtr(pstrFileName, MAX_PATH));

Free();

m_hInst = ::LoadLibraryEx(pstrFileName, NULL, dwFlags);

return m_hInst != NULL;

}

void Free()

{

if( IsLoaded() ) {

::FreeLibrary(m_hInst);

m_hInst = NULL;

}

}

HINSTANCE Detach()

{

HINSTANCE hInst = m_hInst;

m_hInst = NULL;

return hInst;

}

BOOL IsLoaded() const

{

return m_hInst != NULL;

}

FARPROC GetProcAddress(LPCSTR pszFuncName) const

{

ATLASSERT(!::IsBadStringPtrA(pszFuncName,-1));

ATLASSERT(IsLoaded());

return ::GetProcAddress(m_hInst, pszFuncName);

}

BOOL GetFileName(LPTSTR pstrFilename, DWORD cchMax = MAX_PATH) const

{

ATLASSERT(IsLoaded());

return ::GetModuleFileName(m_hInst, pstrFilename, cchMax);

}

operator HINSTANCE() const

{

return m_hInst;

}

};
应用这个封装,上述示例即可这样写:
CLoadLibrary loadEditDll( CRichEditCtrl::GetLibraryName() );

ATLASSERT( loadEditDll.IsLoaded() );