调用API：SHBrowseForFolder()选择文件夹总是报错，为什么？

我写了一个选择文件夹的函数，代码如下：  
  VOID   SelectPath(HWND   hwnd)  
  {  
  BROWSEINFO   bi   =   {   0   };  
  LPMALLOC   pMlc;  
  TCHAR   szDisplayName[MAX_PATH];  
  TCHAR   szPath[MAX_PATH];  
   
  SecureZeroMemory(szDisplayName,   sizeof(szDisplayName)); SecureZeroMemory(szPath,   sizeof(szPath));  
   
  if   (SHGetMalloc(&pMlc)   ==   E_FAIL)  
  {  
  MessageBox(hwnd,    
  TEXT("Call   to   SHGetMalloc()   failed."),  
  TEXT("Error"),  
  MB_OK   |   MB_ICONERROR);  
  return;  
  }  
   
  bi.hwndOwner   =   hwnd;  
  bi.pidlRoot   =   NULL;  
  bi.pszDisplayName   =   szDisplayName;  
  bi.lpszTitle   =   TEXT("Please   select   the   path   to   create   the   file:");  
  bi.ulFlags   =   BIF_NEWDIALOGSTYLE   |   BIF_RETURNONLYFSDIRS;  
   
  LPITEMIDLIST   pIdl   =   SHBrowseForFolder(&bi);  
  if   (pIdl   ==   NULL)  
  {  
  pMlc->Release();  
  return;  
  }  
   
  SHGetPathFromIDList(pIdl,   szPath);  
  if   (szPath[lstrlen(szPath)   -   1]   !=   TEXT('\\'))  
  lstrcat(szPath,   TEXT("\\"));  
  SetWindowText(GetDlgItem(hwnd,   IDC_PATH),   szPath);  
  pMlc->Free(pIdl);  
  pMlc->Release();  
  }  
  在程序的初始化过程中我已经调用了CoInitializeEx(NULL,   COINIT_APARTMENTTHREADED)函数用来加载COM   library，在程序的结束过程中也调用了CoUninitialize()函数用来关闭COM   library。  
  在程序的执行过程中，首次调用SelectPath()时运行正常，但是当我第二或者第三次调用SelectPath()时程序就有可能报如下错误：  
  “xxx”指令引用的内存“xxx”。该内存不能为“written”。  
  而且该错误不是总能再现的，但是出现频率较高。  
   
  请大侠们指点迷津，非常感谢！  
  问题点数：100、回复次数：3Top

1 楼legendhui（秋天的叶子）回复于 2005-04-15 15:34:35 得分 30

You   must   initialize   Component   Object   Model   (COM)   using   CoInitializeEx   with   the   COINIT_APARTMENTTHREADED   flag   set   in   the   dwCoInit   parameter   prior   to   calling   SHBrowseForFolder.   You   can   also   use   CoInitialize   or   OleInitialize,   which   always   use   apartment   threading.  
   
  Note     If   COM   is   initialized   using   CoInitializeEx   with   the   COINIT_MULTITHREADED   flag,   SHBrowseForFolder   fails   if   the   caller   uses   the   BIF_USENEWUI   or   BIF_NEWDIALOGSTYLE   flag   in   the   BROWSEINFO   structure.  
  The   calling   application   is   responsible   for   freeing   the   returned   PIDL   by   using   the   Shell   allocator's   IMalloc::Free   method.   To   retrieve   a   handle   to   that   IMalloc   interface,   call   SHGetMalloc.   For   further   discussion   of   the   Shell   allocator   and   PIDLs,   see   The   Shell   Namespace.  
   
  There   are   two   styles   of   dialog   box   available.   The   older   style   is   displayed   by   default   and   is   not   resizable.   To   specify   a   dialog   box   using   the   newer   style,   set   the   BIF_USENEWUI   flag   in   the   ulFlags   member   of   the   BROWSEINFO   structure.   The   newer   style   provides   a   number   of   additional   features,   including   drag   and   drop   capability   within   the   dialog   box,   reordering,   deletion,   shortcut   menus,   the   ability   to   create   new   folders,   and   other   shortcut   menu   commands.   Initially,   it   is   larger   than   the   older   dialog   box,   but   can   be   resized   by   the   user.  
   
  If   you   implement   a   callback   function,   you   receive   a   handle   to   the   dialog   box.   One   use   of   this   window   handle   is   to   modify   the   layout   or   contents   of   the   dialog   box.   Because   it   is   not   resizable,   modifying   the   older   style   dialog   box   is   relatively   straightforward.   Modifying   the   newer   style   dialog   box   is   much   more   difficult,   and   not   recommended.   Not   only   does   it   have   a   different   size   and   layout   than   the   old   style,   but   its   dimensions   and   the   positions   of   its   controls   change   every   time   it   is   resized   by   the   user.  
   
  If   the   BIF_RETURNONLYFSDIRS   flag   is   set   in   the   ulFlags   member   of   the   BROWSEINFO   structure,   the   OK   button   will   remain   enabled   for   "\\server"   items,   as   well   as   "\\server\share"   and   directory   items.   However,   if   the   user   selects   a   "\\server"   item,   passing   the   returned   PIDL   to   SHGetPathFromIDList   fails.  
   
  Custom   Filtering  
   
  Under   Microsoft®   Windows®   XP,   SHBrowseForFolder   supports   custom   filtering   on   the   contents   of   the   dialog   box.   To   create   a   custom   filter,   follow   these   steps.    
   
  Set   the   BIF_NEWDIALOGSTYLE   flag   in   the   ulFlags   member   of   the   BROWSEINFO   parameter   structure.  
  Specify   a   callback   function   in   the   lpfn   member   of   the   BROWSEINFO   parameter   structure.  
  The   callback   function   receives   BFFM_INITIALIZED   and   BFFM_IUNKNOWN   messages.   On   receipt   of   the   BFFM_IUNKNOWN   message,   the   callback   function's   LPARAM   parameter   contains   a   pointer   to   an   instance   of   IUnknown.   Call   QueryInterface   on   that   IUnknown   to   obtain   a   pointer   to   an   instance   of   IFolderFilterSite.  
  Create   an   object   that   implements   IFolderFilter.  
  Call   IFolderFilterSite::SetFilter,   passing   it   a   pointer   to   your   IFolderFilter.   IFolderFilter   methods   can   then   be   used   to   include   and   exclude   items   from   the   tree.  
  Once   the   filter   is   created,   the   IFolderFilterSite   interface   is   no   longer   needed.   Call   IFolderFilterSite::Release   if   you   have   no   further   use   for   it.Top

2 楼ColderRain（一切尽在不言中）回复于 2005-04-15 20:17:01 得分 40

//   Displays   the   dialog  
  CSBrowseFolder::retCode   CSBrowseFolder::Show(HWND   parent,   LPSTR   pathBuffer)  
  {  
   
  //   Passed   in   a   NULL   pointer   (!)  
  ASSERT(pathBuffer);  
   
  if   (!pathBuffer)  
  return   RET_NOPATH;  
   
  //   Return   value   for   the   function  
  retCode   ret   =   RET_OK;  
   
  LPITEMIDLIST   itemIDList;  
   
  //   Set   up   the   params  
  BROWSEINFO   browseInfo;  
   
  //   The   dialog   must   have   a   parent  
  ASSERT(parent);  
   
  browseInfo.hwndOwner =   parent;  
  browseInfo.pidlRoot =   m_root;  
  browseInfo.pszDisplayName =   m_displayName;  
  browseInfo.lpszTitle =   m_title;  
  browseInfo.ulFlags =   m_style;  
  browseInfo.lpfn =   NULL;  
  browseInfo.lParam =   0;  
   
  //   Show   the   dialog  
  itemIDList   =   SHBrowseForFolder(&browseInfo);  
   
  //   Did   user   press   cancel?  
  if   (!itemIDList)  
  ret   =   RET_CANCEL;  
   
  //   Is   everything   so   far?  
  if   (ret   !=   RET_CANCEL)   {  
   
  //   Get   the   path   from   the   returned   ITEMIDLIST  
  if   (!SHGetPathFromIDList(itemIDList,   pathBuffer))  
  ret   =   RET_NOPATH;  
   
  //   Now   we   need   to   free   the   ITEMIDLIST   the   shell   allocated  
  LPMALLOC shellMalloc;  
  HRESULT hr;  
   
  //   Get   pointer   to   the   shell's   malloc   interface  
  hr   =   SHGetMalloc(&shellMalloc);  
   
  //   Did   it   work?  
  if   (SUCCEEDED(hr))   {  
   
  //   Free   the   shell's   memory  
  shellMalloc->Free(itemIDList);  
   
  //   Release   the   interface  
  shellMalloc->Release();  
   
  }  
  }  
   
  return   ret;  
  }Top

3 楼vcmute（BCare4 H1Rest Good9!）回复于 2005-04-16 09:15:39 得分 30

我这正常  
  去掉BIF_NEWDIALOGSTYLE看看  
  还有你的SecureZeroMemoryTop

相关问题

• bi
• browseinfo
• shbrowseforfolder
• pmlc
• bif
• szpath
• 调用
• ifolderfiltersite
• newdialogstyle
• pathbuffer

• 帖主：BlueprintIrene
• legendhui
• ColderRain
• vcmute

• Visual C++类图书
• Visual C++类源码下载