作者：朱金灿

来源：http://blog.csdn.net/clever101

在xp系统上进行文件多选，实际上其文件字符串数组的缓冲区是有限，并不能支持选择任意多个文件，为此以前我还写过一篇文章：使用CFileDialog的钩子函数解决对话框的多选问题。实际上这种做法在vista系统及win7系统上并不支持。那么如何在vista系统及win7系统支持打开文件对话框任意多选文件呢？我想到windows是一个基于com的系统，没准使用com接口能做到。事实上是这样的，需要使用一个叫IFileOpenDialog的接口类。下面是示例代码：

// Return the file system path for a given IShellItem.
static bool PathFromShellItem ( IShellItem* pItem, CString& sPath )
{HRESULT hr;LPOLESTR pwsz = NULL;hr = pItem->GetDisplayName ( SIGDN_FILESYSPATH, &pwsz );if ( FAILED(hr) )return false;sPath = pwsz;CoTaskMemFree ( pwsz );return true;
}// Convert a pipe-separated list of filter strings into a vector of
// COMDLG_FILTERSPEC. The vector<CString> is needed to actually hold the strings
// that the COMDLG_FILTERSPEC structs will point to.
static bool BuildFilterSpecList (_U_STRINGorID szFilterList,COMDLG_FILTERSPEC*& pVecFilter,int& nFilterNum )
{std::vector<CString> vecsFilterParts;CString sFilterList = szFilterList.m_lpstr;CString sToken;int nIdx = 0;// Split the passed-in filter list on pipe characters (MFC-style)for(;;){sToken = sFilterList.Tokenize(_T("|"), nIdx );if ( sToken.IsEmpty() )break;vecsFilterParts.push_back ( sToken );}// There should be an even number of tokens in the stringif ( vecsFilterParts.size() & 1 ){ATLASSERT(0);vecsFilterParts.pop_back();}if(vecsFilterParts.empty())return false;nFilterNum = vecsFilterParts.size()/2.0;pVecFilter = new COMDLG_FILTERSPEC[nFilterNum];// Use each pair of tokens for a COMDLG_FILTERSPEC struct./*for (std::vector<CString>::size_type i = 0; i < vecsFilterParts.size(); i += 2 )*/for (std::vector<CString>::size_type i = 0; i <nFilterNum; i++){USES_CONVERSION;int j = i*2;std::wstring strName = A2W(vecsFilterParts[j]);pVecFilter[i].pszName = new WCHAR[strName.length()+1];memset((void*)pVecFilter[i].pszName,'\0',(strName.length()+1)*sizeof(WCHAR));wcsncpy((wchar_t*)pVecFilter[i].pszName,strName.c_str(),strName.length());j = j+1;std::wstring strSpec = A2W(vecsFilterParts[j]);pVecFilter[i].pszSpec = new WCHAR[strSpec.length()+1];memset((void*)pVecFilter[i].pszSpec,'\0',(strSpec.length()+1)*sizeof(WCHAR));wcsncpy((wchar_t*)pVecFilter[i].pszSpec,strSpec.c_str(),strSpec.length());}
//  return !vecFilters.empty();return true;
}void CMultiSelectDlg::OnBnClickedBtnVista()
{// TODO: 在此添加控件通知处理程序代码HRESULT hr;CComPtr<IFileOpenDialog> pDlg;
//  std::vector<CString> vecsFilterParts;
//  std::vector<COMDLG_FILTERSPEC> vecFilters;COMDLG_FILTERSPEC* pVecFilter = NULL;;int nFilterNum = 0;//   std::vector<std::wstring> vecFilters;CString sDlgTitle = _T("Multi-selection File Open Dialog");CString sOKButtonLabel = _T("确定");CString sFilenameLabel = _T("文件名(N):");DWORD dwFlags = 0;// Create the file-open dialog COM object.hr = pDlg.CoCreateInstance( __uuidof(FileOpenDialog) );if ( FAILED(hr) )return;// Tell the dlg to load the state data associated with this GUID:// {7D5FE367-E148-4a96-B326-42EF237A3662}// This is not strictly necessary for our app (normally you'd wand loads// and saves to share the same state data) but I'm putting this in for the demo.static const GUID guidFileOpen = { 0x7D5FE367, 0xE148, 0x4A96, { 0xB3, 0x26, 0x42, 0xEF, 0x23, 0x7A, 0x36, 0x62 } };hr = pDlg->SetClientGuid ( guidFileOpen );// Call this helper function to convert a pipe-separated file spec list // (like MFC uses) to a vector of COMDLG_FILTERSPEC.if ( BuildFilterSpecList(_T("Text files (*.txt)|*.txt|Executable files (*.exe;*.dll)|*.exe;*.dll|All files (*.*)|*.*|"),pVecFilter,nFilterNum))hr = pDlg->SetFileTypes(nFilterNum,pVecFilter);// Set some other properties of the dialog. It's not the end of the world if// any of these calls fail.USES_CONVERSION; hr = pDlg->SetTitle (A2W(sDlgTitle));hr = pDlg->SetOkButtonLabel(A2W(sOKButtonLabel));hr = pDlg->SetFileNameLabel(A2W(sFilenameLabel));// Set the multi-select option flag.hr = pDlg->GetOptions ( &dwFlags );hr = pDlg->SetOptions ( dwFlags | FOS_ALLOWMULTISELECT );// Set up our event listener.
//  CComObjectStackEx<CDlgEventHandler> cbk;// Show the dialog!hr = pDlg->Show ( m_hWnd );//if ( bAdvised )// pDlg->Unadvise ( dwCookie );// Get the list of selected items and add each filename to the list ctrl.if ( SUCCEEDED(hr) ){CComPtr<IShellItemArray> pItemArray;hr = pDlg->GetResults ( &pItemArray );if ( SUCCEEDED(hr) ){DWORD cSelItems;hr = pItemArray->GetCount ( &cSelItems );if ( SUCCEEDED(hr) ){int nCount = 0;for ( DWORD j = 0; j < cSelItems; j++ ){CComPtr<IShellItem> pItem;hr = pItemArray->GetItemAt ( j, &pItem );if ( SUCCEEDED(hr) ){CString sPath;if ( PathFromShellItem ( pItem, sPath ) ){m_listbox.AddString(sPath);nCount++;}}}CString str;str.Format(_T("%u files selected"), nCount);m_static.SetWindowText(str);}}}for (int i  = 0;i<nFilterNum;i++){delete []pVecFilter[i].pszName;delete []pVecFilter[i].pszSpec;}delete []pVecFilter;
}

值得注意的是这个做法并不兼容xp系统，因此在使用哪种做法时需要你先对操作系统的版本进行判断。我专门写了一个例程供大家参考：VC文件多选对话框

参考文献：

1. WindowsVista for Developers——第六部分：新的文件对话框

2. IFileDialog使用指南