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

如果你有一个很大的扩展列表要检查，你可以使用下面的。我不想创建很多OR语句，所以我修改了lette写的东西。

string supportedExtensions = "*.jpg,*.gif,*.png,*.bmp,*.jpe,*.jpeg,*.wmf,*.emf,*.xbm,*.ico,*.eps,*.tif,*.tiff,*.g01,*.g02,*.g03,*.g04,*.g05,*.g06,*.g07,*.g08";
foreach (string imageFile in Directory.GetFiles(_tempDirectory, "*.*", SearchOption.AllDirectories).Where(s => supportedExtensions.Contains(Path.GetExtension(s).ToLower())))
{
    //do work here
}

对于。net 4.0及更高版本，

var files = Directory.EnumerateFiles("C:\\path", "*.*", SearchOption.AllDirectories)
            .Where(s => s.EndsWith(".mp3") || s.EndsWith(".jpg"));

对于。net的早期版本，

var files = Directory.GetFiles("C:\\path", "*.*", SearchOption.AllDirectories)
            .Where(s => s.EndsWith(".mp3") || s.EndsWith(".jpg"));

编辑:请阅读评论。Paul Farry提出的改进，以及Christian提出的记忆/性能问题。K点都很重要。

在。net 2.0中(没有Linq):

public static List<string> GetFilez(string path, System.IO.SearchOption opt,  params string[] patterns)
{
    List<string> filez = new List<string>();
    foreach (string pattern in patterns)
    {
        filez.AddRange(
            System.IO.Directory.GetFiles(path, pattern, opt)
        );
    }


    // filez.Sort(); // Optional
    return filez; // Optional: .ToArray()
}

然后使用它:

foreach (string fn in GetFilez(path
                             , System.IO.SearchOption.AllDirectories
                             , "*.xml", "*.xml.rels", "*.rels"))
{}

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");