DirectoryInfo directory = new DirectoryInfo(Server.MapPath("~/Contents/"));

//Using Union

FileInfo[] files = directory.GetFiles("*.xlsx")
                            .Union(directory
                            .GetFiles("*.csv"))
                            .ToArray();

让你想要的扩展名为一个字符串，即“.mp3.jpg.wma.wmf”，然后检查每个文件是否包含你想要的扩展名。 这适用于。net 2.0，因为它不使用LINQ。

string myExtensions=".jpg.mp3";

string[] files=System.IO.Directory.GetFiles("C:\myfolder");

foreach(string file in files)
{
   if(myExtensions.ToLower().contains(System.IO.Path.GetExtension(s).ToLower()))
   {
      //this file has passed, do something with this file

   }
}

这种方法的优点是你可以添加或删除扩展，而不需要编辑代码，即添加png图像，只需写myExtensions=".jpg.mp3.png"。

/// <summary>
/// Returns the names of files in a specified directories that match the specified patterns using LINQ
/// </summary>
/// <param name="srcDirs">The directories to seach</param>
/// <param name="searchPatterns">the list of search patterns</param>
/// <param name="searchOption"></param>
/// <returns>The list of files that match the specified pattern</returns>
public static string[] GetFilesUsingLINQ(string[] srcDirs,
     string[] searchPatterns,
     SearchOption searchOption = SearchOption.AllDirectories)
{
    var r = from dir in srcDirs
            from searchPattern in searchPatterns
            from f in Directory.GetFiles(dir, searchPattern, searchOption)
            select f;

    return r.ToArray();
}

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

Let

var set = new HashSet<string>(
    new[] { ".mp3", ".jpg" },
    StringComparer.OrdinalIgnoreCase); // ignore case
var dir = new DirectoryInfo(path);

Then

dir.EnumerateFiles("*.*", SearchOption.AllDirectories)
   .Where(f => set.Contains(f.Extension));

or

from file in dir.EnumerateFiles("*.*", SearchOption.AllDirectories)
from ext in set // makes sense only if it's just IEnumerable<string> or similar
where String.Equals(ext, file.Extension, StringComparison.OrdinalIgnoreCase)
select file;