http://www.oschina.net/code/snippet_228738_46534

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Security.Permissions;
using System.Runtime.InteropServices;
using System.Management;

class DriverAndFileService
{
    [DllImport("kernel32.dll")]
    public static extern IntPtr _lopen(string lpPathName, int iReadWrite);
    [DllImport("kernel32.dll")]
    public static extern bool CloseHandle(IntPtr hObject);
    public const int OF_READWRITE = 2;
    public const int OF_SHARE_DENY_NONE = 0x40;
    public static readonly IntPtr HFILE_ERROR = new IntPtr(-1);

    List<String> fileList = new System.Collections.Generic.List<string>();
     /// <summary>
     /// 获得驱动器列表
     /// </summary>
     /// <param name="path"></param>
     /// <returns></returns>
     public static List<String> getDriversList()
     {
         List<String> list = new System.Collections.Generic.List<string>();
         DriveInfo[] volumes = DriveInfo.GetDrives();

         foreach (DriveInfo di in volumes)
         {
             list.Add(di.Name);
         }
         return list;
     }

    /// <summary>
    /// 列出文件夹下面的所有文件
    /// </summary>
    /// <param name="info"></param>
    /// <param name="Filter">Filter为null列出所有文件，注意扩展名必须带.</param>
    /// <returns></returns>
     public List<String> getPathFiles(FileSystemInfo info, String[] Filter,System.ComponentModel.BackgroundWorker worker)
     {
         DirectoryInfo dir = info as DirectoryInfo;
         //不是目录 

         try
         {
             FileSystemInfo[] files = dir.GetFileSystemInfos();
             for (int i = 0; i < files.Length; i++)
             {
                 FileInfo file = files[i] as FileInfo;

                 if (file != null)
                 {
                    //不获取回收站的内容
                     if (file.FullName.Contains("$RECYCLE.BIN") == false)
                     {
                         if (Filter != null)
                         {
                             foreach (String f in Filter)
                             {
                                 if (file.Extension.ToLower().Equals(f.ToLower()))
                                 {
                                     fileList.Add(file.FullName);
                                     if (worker != null)
                                     {
                                         worker.ReportProgress(fileList.Count);
                                     }
                                 }
                             }
                         }
                         else
                         {
                             fileList.Add(file.FullName);
                         }

                     }
                 }
                 //对于子目录，进行递归调用 
                 else
                 {
                     getPathFiles(files[i], Filter, worker);
                 }

             }
         }
         catch (Exception ex)
         {
             throw ex;
         }
         return fileList;
     }

     /// <summary>
     /// 列出文件夹下面的所有文件
     /// </summary>
     /// <param name="info"></param>
     /// <param name="Filter"></param>
     /// <returns></returns>
     public List<String> getPathFiles(FileSystemInfo info, String[] Filter)
     {
         return getPathFiles(info,Filter,null);

     }

     /// <summary>
     /// 检查文件是否处于编辑状态
     /// </summary>
     /// <param name="FileName"></param>
     /// <returns></returns>
     [PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
     private static bool isUsing(String FileName)
     {
         string vFileName = FileName;
         IntPtr vHandle = _lopen(vFileName, OF_READWRITE | OF_SHARE_DENY_NONE);
         if (vHandle == HFILE_ERROR)
         {
             return true;
         }
         CloseHandle(vHandle);
         return false;
     }

     public static List<string> GetNtfsFiles(IEnumerable<string> enumList, String[] Filter)
     {
         List<String> ntfsList = new List<string>();
         foreach (String s in enumList)
         {
             foreach(String filter in Filter)
             {
                 if(s.ToLower().EndsWith(filter))
                 {
                     if (File.Exists(s) && (s.Contains("$RECYCLE.BIN")==false)&&(File.GetAttributes(s)!=FileAttributes.Hidden)) 
                     {
                         ntfsList.Add(s);
                     } 
                 }
             }
         }
         return ntfsList;
     }
}