这个怎么样:

private static string[] GetFiles(string sourceFolder, string filters, System.IO.SearchOption searchOption)
{
   return filters.Split('|').SelectMany(filter => System.IO.Directory.GetFiles(sourceFolder, filter, searchOption)).ToArray();
}

我在这里(评论中)找到了它:http://msdn.microsoft.com/en-us/library/wz42302f.aspx

我有同样的问题，找不到正确的解决方案，所以我写了一个函数叫GetFiles:

/// <summary>
/// Get all files with a specific extension
/// </summary>
/// <param name="extensionsToCompare">string list of all the extensions</param>
/// <param name="Location">string of the location</param>
/// <returns>array of all the files with the specific extensions</returns>
public string[] GetFiles(List<string> extensionsToCompare, string Location)
{
    List<string> files = new List<string>();
    foreach (string file in Directory.GetFiles(Location))
    {
        if (extensionsToCompare.Contains(file.Substring(file.IndexOf('.')+1).ToLower())) files.Add(file);
    }
    files.Sort();
    return files.ToArray();
}

这个函数只调用Directory.Getfiles()一次。

例如，像这样调用函数:

string[] images = GetFiles(new List<string>{"jpg", "png", "gif"}, "imageFolder");

编辑:要获得一个具有多个扩展名的文件，请使用这个文件:

/// <summary>
    /// Get the file with a specific name and extension
    /// </summary>
    /// <param name="filename">the name of the file to find</param>
    /// <param name="extensionsToCompare">string list of all the extensions</param>
    /// <param name="Location">string of the location</param>
    /// <returns>file with the requested filename</returns>
    public string GetFile( string filename, List<string> extensionsToCompare, string Location)
    {
        foreach (string file in Directory.GetFiles(Location))
        {
            if (extensionsToCompare.Contains(file.Substring(file.IndexOf('.') + 1).ToLower()) &&& file.Substring(Location.Length + 1, (file.IndexOf('.') - (Location.Length + 1))).ToLower() == filename) 
                return file;
        }
        return "";
    }

例如，像这样调用函数:

string image = GetFile("imagename", new List<string>{"jpg", "png", "gif"}, "imageFolder");

List<string> FileList = new List<string>();
DirectoryInfo di = new DirectoryInfo("C:\\DirName");

IEnumerable<FileInfo> fileList = di.GetFiles("*.*");

//Create the query
IEnumerable<FileInfo> fileQuery = from file in fileList
                                  where (file.Extension.ToLower() == ".jpg" || file.Extension.ToLower() == ".png")
                                  orderby file.LastWriteTime
                                  select file;

foreach (System.IO.FileInfo fi in fileQuery)
{
    fi.Attributes = FileAttributes.Normal;
    FileList.Add(fi.FullName);
}

我不知道哪种解决方案更好，但我用这个:

String[] ext = "*.ext1|*.ext2".Split('|');

            List<String> files = new List<String>();
            foreach (String tmp in ext)
            {
                files.AddRange(Directory.GetFiles(dir, tmp, SearchOption.AllDirectories));
            }

只是找到了另一种方法。仍然不是一次操作，而是把它扔出去，看看其他人是怎么想的。

private void getFiles(string path)
{
    foreach (string s in Array.FindAll(Directory.GetFiles(path, "*", SearchOption.AllDirectories), predicate_FileMatch))
    {
        Debug.Print(s);
    }
}

private bool predicate_FileMatch(string fileName)
{
    if (fileName.EndsWith(".mp3"))
        return true;
    if (fileName.EndsWith(".jpg"))
        return true;
    return false;
}

这个怎么样:

private static string[] GetFiles(string sourceFolder, string filters, System.IO.SearchOption searchOption)
{
   return filters.Split('|').SelectMany(filter => System.IO.Directory.GetFiles(sourceFolder, filter, searchOption)).ToArray();
}

我在这里(评论中)找到了它:http://msdn.microsoft.com/en-us/library/wz42302f.aspx