还有一个下降解决方案，似乎没有任何内存或性能开销，而且相当优雅:

string[] filters = new[]{"*.jpg", "*.png", "*.gif"};
string[] filePaths = filters.SelectMany(f => Directory.GetFiles(basePath, f)).ToArray();

是什么

string[] filesPNG = Directory.GetFiles(path, "*.png");
string[] filesJPG = Directory.GetFiles(path, "*.jpg");
string[] filesJPEG = Directory.GetFiles(path, "*.jpeg");

int totalArraySizeAll = filesPNG.Length + filesJPG.Length + filesJPEG.Length;
List<string> filesAll = new List<string>(totalArraySizeAll);
filesAll.AddRange(filesPNG);
filesAll.AddRange(filesJPG);
filesAll.AddRange(filesJPEG);

Using GetFiles search pattern for filtering the extension is not safe!! For instance you have two file Test1.xls and Test2.xlsx and you want to filter out xls file using search pattern *.xls, but GetFiles return both Test1.xls and Test2.xlsx I was not aware of this and got error in production environment when some temporary files suddenly was handled as right files. Search pattern was *.txt and temp files was named *.txt20181028_100753898 So search pattern can not be trusted, you have to add extra check on filenames as well.

另一种使用Linq的方式，但是不需要返回所有内容并在内存中过滤。

var files = Directory.GetFiles("C:\\path", "*.mp3", SearchOption.AllDirectories).Union(Directory.GetFiles("C:\\path", "*.jpg", SearchOption.AllDirectories));

它实际上是对GetFiles()的2次调用，但我认为这与问题的精神是一致的，并以一个可枚举的形式返回它们。

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。

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
}