C# 删除所有空子目录

Question

我的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文件或子目录，则该目录将被删除。我希望有人能给我指出一些现有的代码，而不是重新发明轮子。我将使用 C# 来完成此操作。

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

如果您可以以 .NET 4.0 为目标，则可以使用 Directory 类上的新方法来枚举目录，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。

这些方法是：

• 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) { }
}

您还提到目录树可能非常深，因此如果您探测的路径太长，您可能会遇到一些异常。

Answer 3

在 C:\Windows 上对到目前为止提到的 3 种方法运行测试 1000 次，结果如下：

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

在空文件夹上运行测试，结果如下（再次 1000 次）：

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

因此，当您检查空文件夹时，EnumerateFileSystemEntries 是迄今为止最好的整体结果。

Answer 4

这是一个利用并行执行在某些情况下更快地完成任务的版本：

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);
  }
}

...这是一些示例代码，您可以使用它来测试您的场景：

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);
}

...以下是我的计算机针对广域网文件共享上的目录的一些结果。此共享当前只有 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 5

从此处，用于删除空目录的 Powershell 脚本：

$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
      }
}

<强>注意：使用风险自负！

Answer 6

如果您仅依赖 DirectoryInfo.Delete 删除空目录，则可以编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 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 { }
        }
    }

Answer 10

foreach (var emptyDir in Directory.GetDirectories(root,"*",SearchOption.AllDirectories)
                                  .Select(p=>new DirectoryInfo(p))
                                  .Where(p=>p.GetFiles("*.*", SearchOption.AllDirectories).Count() == 0))
{
        
    if(emptyDir.Exists){emptyDir.Delete(true);}

    
}