c# - 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，则将删除它。我希望有人可以为我指出一些现有的代码，而不必重新发明轮子。我将使用 C# 来执行此操作。

score 108 · Accepted Answer

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);
        }
    }
}

score 49 · Accepted Answer

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，以便在您只想知道是否至少有一个文件时，在列出目录中的每个文件时不会付出性能损失。

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。

score 11 · Accepted Answer

使用目前提到的 3 种方法在 C:\Windows 上运行 1000 次测试，结果如下：

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

在一个空文件夹上运行它会产生这个（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。

score 4 · Accepted Answer

这是一个利用并行执行在某些情况下更快完成的版本：

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);
  }
}

...这里有一些示例代码可用于在您的场景中测试结果：

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);
}

...这是我机器上的一些结果，该目录位于广域网的文件共享中。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

score 3 · Accepted Answer

从这里，Powershell 脚本删除空目录：

$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：使用风险自负！

score 3 · Accepted Answer

如果DirectoryInfo.Delete只依赖删除空目录，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();
}

score 1 · Accepted Answer

    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);
        }
    }
}

score 0 · Accepted Answer

//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) */

score 0 · Accepted Answer

    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# - C# 删除所有空子目录

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