下面是一种获得过滤文件的简单而优雅的方法

var allowedFileExtensions = ".csv,.txt";


var files = Directory.EnumerateFiles(@"C:\MyFolder", "*.*", SearchOption.TopDirectoryOnly)
                .Where(s => allowedFileExtensions.IndexOf(Path.GetExtension(s)) > -1).ToArray(); 

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));
            }

我不能使用. where方法，因为我在. net Framework 2.0中编程(Linq只在. net Framework 3.5+中被支持)。

下面的代码不区分大小写(因此.cab或.cab也会被列出)。

string[] ext = new string[2] { "*.CAB", "*.MSU" };

foreach (string found in ext)
{
    string[] extracted = Directory.GetFiles("C:\\test", found, System.IO.SearchOption.AllDirectories);

    foreach (string file in extracted)
    {
        Console.WriteLine(file);
    }
}

如果你使用VB。NET(或将依赖导入到你的c#项目中)，实际上存在一个方便的方法，允许过滤多个扩展:

Microsoft.VisualBasic.FileIO.FileSystem.GetFiles("C:\\path", Microsoft.VisualBasic.FileIO.SearchOption.SearchAllSubDirectories, new string[] {"*.mp3", "*.jpg"});

在VB。NET可以通过My-namespace访问:

My.Computer.FileSystem.GetFiles("C:\path", FileIO.SearchOption.SearchAllSubDirectories, {"*.mp3", "*.jpg"})

不幸的是，这些方便的方法不支持像Directory.EnumerateFiles()那样的惰性求值变体。

/// <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();
}

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