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 string

	if ( 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