作者：Alexei Evdokimov 译自：CodeGuru
使用MFC实现COM组件时，经常节省许多开发时间。例如，使用AppWizard生成的基于MFC的COM dll工程，已经自动的提供了DllRegisterServer功能的实现。然而，却没有自动生成DllUnregisterServer功能。一般情况下，DllUnregisterServer对于程序是不可缺少的，因为一个完整的程序，不仅需要自注册功能，同时也需要自卸载功能。
基于MFC实现DllRegisterServer()的方法是调用COleObjectFactory::UpdateRegistryAll()。这个方法有一个未公开的参数-(BOOL bRegister = TRUE) - 因此，我们猜测通过调用COleObjectFactory::UpdateRegistry(FALSE)将能够实卸载COM dll的功能。但是，事实并非如此。通过分析源代码，我们能够知道COleObjectFactory::UpdateRegistryAll(BOOL bRegister)通过同样的BOOL值调用COleObjectFactory::UpdateRegistry(BOOL bRegister),但是COleObjectFactory::UpdateRegistry(BOOL bRegister)的实现调用UpdateRegistry(LPCTSTR lpszProgID)函数，这个调用仅当bRegister为TRUE时注册组件,否则什么都不做！
所以，有必要写我们自己的DllUnregisterServer()。下面的代码能够实现基于MFC的DllUnregisterServer()，并且使用非常的简单。使用方法：
- 创建文件DllUnregisterServer_MFC_Impl.inl
- 把下面的代码拷贝/粘贴到新建的文件中
- 在dll的主文件.cpp中(dll_name.cpp)加入:
#include "DllUnregisterServer_MFC_Impl.inl"
- 在dll_name.def文件的EXPORTS片断中加入:
DllUnregisterServer PRIVATE
完成！现在你可以使用"regsvr32 /u dll_name.dll"完成组件的卸载了。
以下代码测试环境为VC++ 5.0, VC++ 5.0 SP3, VC++ 6.0，ANSI环境。也可用于UNICODE环境。
//**************************************************************************
// Date : 11.15.98
// Header : DllUnregisterServer_MFC_Impl.inl
//
// Desc.:DllUnregisterServer() helper for the inproc servers that were
//registered via MFC’s COleObjectFactory::UpdateRegistryAll()
//
// Usage:
//Add ’#include "DllUnregisterServer_MFC_Impl.inl"’ to the end of
//the main dll file (i.e. dll_name.cpp).
//
//Add ’DllUnregisterServerPRIVATE’ to EXPORTS section of the
//dll_name.def.
//
// Caution:
//Code below uses undocumented, internal MFC data structures
//and functions. Therefore, probably, it will be necessary to modify
//it, according to the changes in the future versions of MFC.
//Code below is based on the COleObjectFactory::UpdateRegistryAll(),
//in srcolefact.cpp. (srcolereg.cpp - is actual implementation of
//all registry work).
//**************************************************************************
#include "stdafx.h"
// workaround MFC bug - no #ifndef/#endif for afximpl.h header
#if !defined(CRIT_OBJECTFACTORYLIST)
#include <..srcafximpl.h>
#endif//!CRIT_OBJECTFACTORYLIST
//**************************************************************************
static HRESULT UnregisterCOMObject(REFCLSID p_clsid)
{
LPOLESTR t_wzProgID(NULL);
// get ProgID from CLSID and unregister...
HRESULT t_hr = ::ProgIDFromCLSID(p_clsid, &t_wzProgID);
if(FAILED(t_hr))
return t_hr;
// convert OLESTR to LPTSTR
CString t_strProgID(t_wzProgID);
LPCTSTR t_szProgID = t_strProgID.operator LPCTSTR();
// free memory
::CoTaskMemFree(t_wzProgID);
// unregister...
if(AfxOleUnregisterServerClass(p_clsid,
t_szProgID,
t_szProgID,
t_szProgID,
OAT_DISPATCH_OBJECT))
return S_OK;
else
return E_FAIL;
}
//**************************************************************************
// by exporting DllUnregisterServer, you can use regsvr.exe
STDAPI DllUnregisterServer(void)
{
AFX_MANAGE_STATE(AfxGetStaticModuleState());
AFX_MODULE_STATE* pModuleState = AfxGetModuleState();
AfxLockGlobals(CRIT_OBJECTFACTORYLIST);
for(COleObjectFactory* pFactory = pModuleState->m_factoryList;
pFactory != NULL;
pFactory = pFactory->m_pNextFactory)
{
HRESULT t_hr = UnregisterCOMObject(pFactory->GetClassID());
if(FAILED(t_hr))
{
AfxUnlockGlobals(CRIT_OBJECTFACTORYLIST);
return t_hr;
}
}
AfxUnlockGlobals(CRIT_OBJECTFACTORYLIST);
#ifdef _AFXDLL
AfxLockGlobals(CRIT_DYNLINKLIST);
// register extension DLL factories
for(CDynLinkLibrary* pDLL = pModuleState->m_libraryList;
pDLL != NULL;
pDLL = pDLL->m_pNextDLL)
{
for(pFactory = pDLL->m_factoryList;
pFactory != NULL;
pFactory = pFactory->m_pNextFactory)
{
HRESULT t_hr = UnregisterCOMObject(pFactory->GetClassID());
if(FAILED(t_hr))
{
AfxUnlockGlobals(CRIT_DYNLINKLIST);
return t_hr;
}
}
}
AfxUnlockGlobals(CRIT_DYNLINKLIST);
#endif
return S_OK;
}
//**************************************************************************
// end of DllUnregisterServer_MFC_Impl.inl
