C# - 如何快速、优化地列出子目录中的文件

Question

我正在尝试使用以下方法列出根目录的所有子目录中的文件。但是当文件数量以百万计时，它会花费很多时间。有没有更好的方法来做到这一点。

我正在使用 .NET 3.5，所以不能使用枚举器:-(

        ******************* Main *************
        DirectoryInfo dir = new DirectoryInfo(path);
        DirectoryInfo[] subDir = dir.GetDirectories();
        foreach (DirectoryInfo di in subDir) //call for each sub directory
        {
             PopulateList(di.FullName, false);
        }

        *******************************************
        static void PopulateList(string directory, bool IsRoot)
        {

            System.Diagnostics.ProcessStartInfo procStartInfo = new System.Diagnostics.ProcessStartInfo("cmd", "/c " + "dir /s/b \"" + directory + "\"");
            procStartInfo.RedirectStandardOutput = true;
            procStartInfo.UseShellExecute = false;
            procStartInfo.CreateNoWindow = true;
            System.Diagnostics.Process proc = new System.Diagnostics.Process();
            proc.StartInfo = procStartInfo;
            proc.Start();

            string fileName = directory.Substring(directory.LastIndexOf('\\') + 1);
            StreamWriter writer = new StreamWriter(fileName + ".lst");

            while (proc.StandardOutput.EndOfStream != true)
            {
                 writer.WriteLine(proc.StandardOutput.ReadLine());
                 writer.Flush();
            }
            writer.Close();
        }

Answer 1

删除所有与流程相关的内容并尝试 Directory.GetDirectories ()和 Directory.GetFiles()方法:

public IEnumerable<string> GetAllFiles(string rootDirectory)
{
    foreach(var directory in Directory.GetDirectories(
                                            rootDirectory, 
                                            "*", 
                                            SearchOption.AllDirectories))
    {
        foreach(var file in Directory.GetFiles(directory))
        {
            yield return file;
        }
    }
}

来自 MSDN，SearchOption.AllDirectories:

Includes the current directory and all the subdirectories in a search operation. This option includes reparse points like mounted drives and symbolic links in the search.