Question

我有一项任务是清理大量目录。我想从一个目录开始并删除任何不包含文件的子目录（无论多深）（文件永远不会被删除，只有目录）。如果起始目录不包含任何文件或子目录，则将删除该起始目录。我希望有人可以指出一些现有的代码，而不是重新发明轮子。我将使用C＃进行此操作。

Answer 1

使用C＃代码。

static void Main(string[] args)
{
    processDirectory(@"c:\temp");
}

private static void processDirectory(string startLocation)
{
    foreach (var directory in Directory.GetDirectories(startLocation))
    {
        processDirectory(directory);
        if (Directory.GetFiles(directory).Length == 0 && 
            Directory.GetDirectories(directory).Length == 0)
        {
            Directory.Delete(directory, false);
        }
    }
}

Answer 2

如果您可以定位.NET 4.0，则可以使用Directory类上的新方法枚举目录，以便在您只想知道时列出目录中的每个文件时不会造成性能损失如果至少有一个。

方法是：

Directory.EnumerateDirectories
Directory.EnumerateFiles
Directory.EnumerateFileSystemEntries

使用递归的可能实现：

static void Main(string[] args)
{
    DeleteEmptyDirs("Start");
}

static void DeleteEmptyDirs(string dir)
{
    if (String.IsNullOrEmpty(dir))
        throw new ArgumentException(
            "Starting directory is a null reference or an empty string", 
            "dir");

    try
    {
        foreach (var d in Directory.EnumerateDirectories(dir))
        {
            DeleteEmptyDirs(d);
        }

        var entries = Directory.EnumerateFileSystemEntries(dir);

        if (!entries.Any())
        {
            try
            {
                Directory.Delete(dir);
            }
            catch (UnauthorizedAccessException) { }
            catch (DirectoryNotFoundException) { }
        }
    }
    catch (UnauthorizedAccessException) { }
}

你还提到目录树可能非常深，所以如果你探测的路径太长，你可能会遇到一些例外。

Answer 3

在目前为止提到的3种方法上，在C：\ Windows上运行1000次测试产生了这样的结果：

GetFiles+GetDirectories:630ms
GetFileSystemEntries:295ms
EnumerateFileSystemEntries.Any:71ms

在空文件夹上运行它会产生这种情况（再次1000次）：

GetFiles+GetDirectories:131ms
GetFileSystemEntries:66ms
EnumerateFileSystemEntries.Any:64ms

因此，当您检查空文件夹时，EnumerateFileSystemEntries是最好的整体。

Answer 4

从这里开始，Powershell script to remove empty directories：

$items = Get-ChildItem -Recurse

foreach($item in $items)
{
      if( $item.PSIsContainer )
      {
            $subitems = Get-ChildItem -Recurse -Path $item.FullName
            if($subitems -eq $null)
            {
                  "Remove item: " + $item.FullName
                  Remove-Item $item.FullName
            }
            $subitems = $null
      }
}

注意：自担风险使用！

Answer 5

如果你依赖DirectoryInfo.Delete只删除空目录，你可以写一个简洁的扩展方法

public static void DeleteEmptyDirs(this DirectoryInfo dir)
{
    foreach (DirectoryInfo d in dir.GetDirectories())
        d.DeleteEmptyDirs();

    try { dir.Delete(); }
    catch (IOException) {}
    catch (UnauthorizedAccessException) {}
}

用法：

static void Main()
{
    new DirectoryInfo(@"C:\temp").DeleteEmptyDirs();
}

Answer 6

这是一个利用并行执行的版本，可以在某些案例中更快地完成它：

public static void DeleteEmptySubdirectories(string parentDirectory){
  System.Threading.Tasks.Parallel.ForEach(System.IO.Directory.GetDirectories(parentDirectory), directory => {
    DeleteEmptySubdirectories(directory);
    if(!System.IO.Directory.EnumerateFileSystemEntries(directory).Any()) System.IO.Directory.Delete(directory, false);
  });   
}

这是单线程模式下的相同代码：

public static void DeleteEmptySubdirectoriesSingleThread(string parentDirectory){
  foreach(string directory in System.IO.Directory.GetDirectories(parentDirectory)){
    DeleteEmptySubdirectories(directory);
    if(!System.IO.Directory.EnumerateFileSystemEntries(directory).Any()) System.IO.Directory.Delete(directory, false);
  }
}

...这里有一些示例代码可用于测试您的方案中的结果：

var stopWatch = new System.Diagnostics.Stopwatch();
for(int i = 0; i < 100; i++) {
  stopWatch.Restart();
  DeleteEmptySubdirectories(rootPath);
  stopWatch.Stop();
  StatusOutputStream.WriteLine("Parallel: "+stopWatch.ElapsedMilliseconds);
  stopWatch.Restart();
  DeleteEmptySubdirectoriesSingleThread(rootPath);
  stopWatch.Stop();
  StatusOutputStream.WriteLine("Single: "+stopWatch.ElapsedMilliseconds);
}

...这里有一些来自我的机器的结果，用于在广域网上的文件共享上的目录。此分享目前只有16个子文件夹和2277个文件。

Parallel: 1479
Single: 4724
Parallel: 1691
Single: 5603
Parallel: 1540
Single: 4959
Parallel: 1592
Single: 4792
Parallel: 1671
Single: 4849
Parallel: 1485
Single: 4389

Answer 7

    private static void deleteEmptySubFolders(string ffd, bool deleteIfFileSizeZero=false)
{
    DirectoryInfo di = new DirectoryInfo(ffd);
    foreach (DirectoryInfo diSon in di.GetDirectories("*", SearchOption.TopDirectoryOnly))
    {
        FileInfo[] fis = diSon.GetFiles("*.*", SearchOption.AllDirectories);
        if (fis == null || fis.Length < 1)
        {
            diSon.Delete(true);
        }
        else
        {
            if (deleteIfFileSizeZero)
            {
                long total = 0;
                foreach (FileInfo fi in fis)
                {
                    total = total + fi.Length;
                    if (total > 0)
                    {
                        break;
                    }
                }

                if (total == 0)
                {
                    diSon.Delete(true);
                    continue;
                }
            }

            deleteEmptySubFolders(diSon.FullName, deleteIfFileSizeZero);
        }
    }
}

Answer 8

//Recursive scan of empty dirs. See example output bottom

string startDir = @"d:\root";

void Scan(string dir, bool stepBack)
    {
        //directory not empty
        if (Directory.GetFileSystemEntries(dir).Length > 0)
        {
            if (!stepBack)
            {
                foreach (string subdir in Directory.GetDirectories(dir))
                    Scan(subdir, false);
            } 
        }
        //directory empty so delete it.
        else
        {
            Directory.Delete(dir);
            string prevDir = dir.Substring(0, dir.LastIndexOf("\\"));
            if (startDir.Length <= prevDir.Length)
                Scan(prevDir, true);
        }
    }
//call like this
Scan(startDir, false);

/*EXAMPLE outputof d:\root with empty subfolders and one filled with files
   Scanning d:\root
   Scanning d:\root\folder1 (not empty)
   Scanning d:\root\folder1\folder1sub1 (not empty)
   Scanning d:\root\folder1\folder1sub1\folder2sub2 (deleted!)
   Scanning d:\root\folder1\folder1sub1 (deleted!)
   Scanning d:\root\folder1 (deleted)
   Scanning d:\root (not empty)
   Scanning d:\root\folder2 (not empty)
   Scanning d:\root\folder2\folder2sub1 (deleted)
   Scanning d:\root\folder2 (not empty)
   Scanning d:\root\folder2\notempty (not empty) */

Answer 9

    foreach (var folder in Directory.GetDirectories(myDir, "*", System.IO.SearchOption.AllDirectories))
    {
        {
            try
            {
                if (Directory.GetFiles(folder, "*", System.IO.SearchOption.AllDirectories).Length == 0)
                    Directory.Delete(folder, true);
            }
            catch { }
        }
    }

C＃删除所有空子目录

9 个答案: