c# - 检查路径是文件还是目录的更好方法?


我正在处理目录和文件的TreeView 。 用户可以选择一个文件或一个目录,然后做一些事情。 这要求我有一个方法,根据用户的选择执行不同的操作。

目前我正在做这样的事情,以确定路径是一个文件或目录:

bool bIsFile = false;
bool bIsDirectory = false;

try
{
    string[] subfolders = Directory.GetDirectories(strFilePath);

    bIsDirectory = true;
    bIsFile = false;
}
catch(System.IO.IOException)
{
    bIsFolder = false;
    bIsFile = true;
}

我不禁感到有更好的方法来做到这一点! 我希望找到一个标准的.NET方法来处理这个问题,但是我一直没能做到。 这样的方法是否存在,如果不存在,那么确定路径是文件还是目录的最直接方法是什么?



Answers


如何判断路径是文件还是目录

// get the file attributes for file or directory
FileAttributes attr = File.GetAttributes(@"c:\Temp");

//detect whether its a directory or file
if ((attr & FileAttributes.Directory) == FileAttributes.Directory)
    MessageBox.Show("Its a directory");
else
    MessageBox.Show("Its a file");

.NET 4.0+更新

根据下面的注释,如果您使用的是.NET 4.0或更高版本(并且最高性能并不重要),则可以使用更简洁的方式编写代码:

// get the file attributes for file or directory
FileAttributes attr = File.GetAttributes(@"c:\Temp");

if (attr.HasFlag(FileAttributes.Directory))
    MessageBox.Show("Its a directory");
else
    MessageBox.Show("Its a file");



如何使用这些?

File.Exists();
Directory.Exists();



只有这一行,你可以得到如果一个路径是一个目录或文件:

File.GetAttributes(data.Path).HasFlag(FileAttributes.Directory)



最准确的方法是使用shlwapi.dll中的一些互操作代码

[DllImport(SHLWAPI, CharSet = CharSet.Unicode)]
[return: MarshalAsAttribute(UnmanagedType.Bool)]
[ResourceExposure(ResourceScope.None)]
internal static extern bool PathIsDirectory([MarshalAsAttribute(UnmanagedType.LPWStr), In] string pszPath);

你会这样称呼它:

#region IsDirectory
/// <summary>
/// Verifies that a path is a valid directory.
/// </summary>
/// <param name="path">The path to verify.</param>
/// <returns><see langword="true"/> if the path is a valid directory; 
/// otherwise, <see langword="false"/>.</returns>
/// <exception cref="T:System.ArgumentNullException">
/// <para><paramref name="path"/> is <see langword="null"/>.</para>
/// </exception>
/// <exception cref="T:System.ArgumentException">
/// <para><paramref name="path"/> is <see cref="F:System.String.Empty">String.Empty</see>.</para>
/// </exception>
public static bool IsDirectory(string path)
{
    return PathIsDirectory(path);
}



作为Directory.Exists()的替代方法,可以使用File.GetAttributes()方法来获取文件或目录的属性,以便可以创建一个像下面这样的帮助方法:

private static bool IsDirectory(string path)
{
    System.IO.FileAttributes fa = System.IO.File.GetAttributes(path);
    bool isDirectory = false;
    if ((fa & FileAttributes.Directory) != 0)
    {
        isDirectory = true;
    }
    return isDirectory;
}

填充包含该项目的其他元数据的控件时,也可以考虑将对象添加到TreeView控件的标签属性中。 例如,您可以为文件添加FileInfo对象,为目录添加DirectoryInfo对象,然后在标签属性中测试项目类型,以便在点击项目时保存额外的系统调用以获取该数据。




考虑到Exists和Attributes属性的行为,这是我能想到的最好的方法:

using System.IO;

public static class FileSystemInfoExtensions
{
    /// <summary>
    /// Checks whether a FileInfo or DirectoryInfo object is a directory, or intended to be a directory.
    /// </summary>
    /// <param name="fileSystemInfo"></param>
    /// <returns></returns>
    public static bool IsDirectory(this FileSystemInfo fileSystemInfo)
    {
        if (fileSystemInfo == null)
        {
            return false;
        }

        if ((int)fileSystemInfo.Attributes != -1)
        {
            // if attributes are initialized check the directory flag
            return fileSystemInfo.Attributes.HasFlag(FileAttributes.Directory);
        }

        // If we get here the file probably doesn't exist yet.  The best we can do is 
        // try to judge intent.  Because directories can have extensions and files
        // can lack them, we can't rely on filename.
        // 
        // We can reasonably assume that if the path doesn't exist yet and 
        // FileSystemInfo is a DirectoryInfo, a directory is intended.  FileInfo can 
        // make a directory, but it would be a bizarre code path.

        return fileSystemInfo is DirectoryInfo;
    }
}

以下是它如何测试:

    [TestMethod]
    public void IsDirectoryTest()
    {
        // non-existing file, FileAttributes not conclusive, rely on type of FileSystemInfo
        const string nonExistentFile = @"C:\TotallyFakeFile.exe";

        var nonExistentFileDirectoryInfo = new DirectoryInfo(nonExistentFile);
        Assert.IsTrue(nonExistentFileDirectoryInfo.IsDirectory());

        var nonExistentFileFileInfo = new FileInfo(nonExistentFile);
        Assert.IsFalse(nonExistentFileFileInfo.IsDirectory());

        // non-existing directory, FileAttributes not conclusive, rely on type of FileSystemInfo
        const string nonExistentDirectory = @"C:\FakeDirectory";

        var nonExistentDirectoryInfo = new DirectoryInfo(nonExistentDirectory);
        Assert.IsTrue(nonExistentDirectoryInfo.IsDirectory());

        var nonExistentFileInfo = new FileInfo(nonExistentDirectory);
        Assert.IsFalse(nonExistentFileInfo.IsDirectory());

        // Existing, rely on FileAttributes
        const string existingDirectory = @"C:\Windows";

        var existingDirectoryInfo = new DirectoryInfo(existingDirectory);
        Assert.IsTrue(existingDirectoryInfo.IsDirectory());

        var existingDirectoryFileInfo = new FileInfo(existingDirectory);
        Assert.IsTrue(existingDirectoryFileInfo.IsDirectory());

        // Existing, rely on FileAttributes
        const string existingFile = @"C:\Windows\notepad.exe";

        var existingFileDirectoryInfo = new DirectoryInfo(existingFile);
        Assert.IsFalse(existingFileDirectoryInfo.IsDirectory());

        var existingFileFileInfo = new FileInfo(existingFile);
        Assert.IsFalse(existingFileFileInfo.IsDirectory());
    }



这是我的:

    bool IsPathDirectory(string path)
    {
        if (path == null) throw new ArgumentNullException("path");
        path = path.Trim();

        if (Directory.Exists(path)) 
            return true;

        if (File.Exists(path)) 
            return false;

        // neither file nor directory exists. guess intention

        // if has trailing slash then it's a directory
        if (new[] {"\\", "/"}.Any(x => path.EndsWith(x)))
            return true; // ends with slash

        // if has extension then its a file; directory otherwise
        return string.IsNullOrWhiteSpace(Path.GetExtension(path));
    }

这与其他人的答案类似,但不完全相同。




当遇到类似的问题时,我遇到了这个问题,除了我需要检查一个文件或文件夹的路径是否可能实际不存在时 。 上面的答案有几条评论提到他们不适合这种情况。 我找到了一个解决方案(我使用VB.NET,但你可以转换,如果你需要的话)似乎对我很好:

Dim path As String = "myFakeFolder\ThisDoesNotExist\"
Dim bIsFolder As Boolean = (IO.Path.GetExtension(path) = "")
'returns True

Dim path As String = "myFakeFolder\ThisDoesNotExist\File.jpg"
Dim bIsFolder As Boolean = (IO.Path.GetExtension(path) = "")
'returns False

希望这可以帮助一个人!




所以在我知道的游戏后期,但是我认为我会分享这个。 如果你只是把路径当作字符串来工作,搞清楚这一点很简单:

private bool IsFolder(string ThePath)
{
    string BS = Path.DirectorySeparatorChar.ToString();
    return Path.GetDirectoryName(ThePath) == ThePath.TrimEnd(BS.ToCharArray());
}

例如: ThePath == "C:\SomeFolder\File1.txt"最终会是这样的:

return "C:\SomeFolder" == "C:\SomeFolder\File1.txt" (FALSE)

另一个例子: ThePath == "C:\SomeFolder\"最终会变成这样:

return "C:\SomeFolder" == "C:\SomeFolder" (TRUE)

而且这也将工作没有后面的反斜杠: ThePath == "C:\SomeFolder"将最终是这样的:

return "C:\SomeFolder" == "C:\SomeFolder" (TRUE)

请记住,这只适用于路径本身,而不是路径和“物理磁盘”之间的关系...所以它不能告诉你路径/文件是否存在或类似的东西,但它确定可以告诉你,如果路径是一个文件夹或文件...




以下是我们使用的:

using System;

using System.IO;

namespace crmachine.CommonClasses
{

  public static class CRMPath
  {

    public static bool IsDirectory(string path)
    {
      if (path == null)
      {
        throw new ArgumentNullException("path");
      }

      string reason;
      if (!IsValidPathString(path, out reason))
      {
        throw new ArgumentException(reason);
      }

      if (!(Directory.Exists(path) || File.Exists(path)))
      {
        throw new InvalidOperationException(string.Format("Could not find a part of the path '{0}'",path));
      }

      return (new System.IO.FileInfo(path).Attributes & FileAttributes.Directory) == FileAttributes.Directory;
    } 

    public static bool IsValidPathString(string pathStringToTest, out string reasonForError)
    {
      reasonForError = "";
      if (string.IsNullOrWhiteSpace(pathStringToTest))
      {
        reasonForError = "Path is Null or Whitespace.";
        return false;
      }
      if (pathStringToTest.Length > CRMConst.MAXPATH) // MAXPATH == 260
      {
        reasonForError = "Length of path exceeds MAXPATH.";
        return false;
      }
      if (PathContainsInvalidCharacters(pathStringToTest))
      {
        reasonForError = "Path contains invalid path characters.";
        return false;
      }
      if (pathStringToTest == ":")
      {
        reasonForError = "Path consists of only a volume designator.";
        return false;
      }
      if (pathStringToTest[0] == ':')
      {
        reasonForError = "Path begins with a volume designator.";
        return false;
      }

      if (pathStringToTest.Contains(":") && pathStringToTest.IndexOf(':') != 1)
      {
        reasonForError = "Path contains a volume designator that is not part of a drive label.";
        return false;
      }
      return true;
    }

    public static bool PathContainsInvalidCharacters(string path)
    {
      if (path == null)
      {
        throw new ArgumentNullException("path");
      }

      bool containedInvalidCharacters = false;

      for (int i = 0; i < path.Length; i++)
      {
        int n = path[i];
        if (
            (n == 0x22) || // "
            (n == 0x3c) || // <
            (n == 0x3e) || // >
            (n == 0x7c) || // |
            (n  < 0x20)    // the control characters
          )
        {
          containedInvalidCharacters = true;
        }
      }

      return containedInvalidCharacters;
    }


    public static bool FilenameContainsInvalidCharacters(string filename)
    {
      if (filename == null)
      {
        throw new ArgumentNullException("filename");
      }

      bool containedInvalidCharacters = false;

      for (int i = 0; i < filename.Length; i++)
      {
        int n = filename[i];
        if (
            (n == 0x22) || // "
            (n == 0x3c) || // <
            (n == 0x3e) || // >
            (n == 0x7c) || // |
            (n == 0x3a) || // : 
            (n == 0x2a) || // * 
            (n == 0x3f) || // ? 
            (n == 0x5c) || // \ 
            (n == 0x2f) || // /
            (n  < 0x20)    // the control characters
          )
        {
          containedInvalidCharacters = true;
        }
      }

      return containedInvalidCharacters;
    }

  }

}



我使用以下内容,它也测试扩展,这意味着它可以用于测试,如果提供的路径是一个文件,但不存在的文件。

private static bool isDirectory(string path)
{
    bool result = true;
    System.IO.FileInfo fileTest = new System.IO.FileInfo(path);
    if (fileTest.Exists == true)
    {
        result = false;
    }
    else
    {
        if (fileTest.Extension != "")
        {
            result = false;
        }
    }
    return result;
}



如果你想查找目录,包括那些标记为“隐藏”和“系统”的目录,试试这个(需要.NET V4):

FileAttributes fa = File.GetAttributes(path);
if(fa.HasFlag(FileAttributes.Directory)) 



using System;
using System.IO;
namespace FileOrDirectory
{
     class Program
     {
          public static string FileOrDirectory(string path)
          {
               if (File.Exists(path))
                    return "File";
               if (Directory.Exists(path))
                    return "Directory";
               return "Path Not Exists";
          }
          static void Main()
          {
               Console.WriteLine("Enter The Path:");
               string path = Console.ReadLine();
               Console.WriteLine(FileOrDirectory(path));
          }
     }
}



我需要这个,帖子帮助,这将它归结为一行,如果路径根本不是一个路径,它只是返回并退出该方法。 它解决了所有上述问题,也不需要结尾的斜线。

if (!Directory.Exists(@"C:\folderName")) return;



在这篇文章中使用选择的答案,我看了评论,并给予@ŞafakGür,@Anthony和@Quinn Wilson的信任他们的信息位,使我得到了这个改进的答案,我写和测试:

    /// <summary>
    /// Returns true if the path is a dir, false if it's a file and null if it's neither or doesn't exist.
    /// </summary>
    /// <param name="path"></param>
    /// <returns></returns>
    public static bool? IsDirFile(this string path)
    {
        bool? result = null;

        if(Directory.Exists(path) || File.Exists(path))
        {
            // get the file attributes for file or directory
            var fileAttr = File.GetAttributes(path);

            if (fileAttr.HasFlag(FileAttributes.Directory))
                result = true;
            else
                result = false;
        }

        return result;
    }



结合其他答案的建议后,我意识到我提出了与罗尼·奥弗比的回答大致相同的东西。 下面是一些测试,指出一些事情要考虑:

  1. 文件夹可以有“扩展名”: C:\Temp\folder_with.dot
  2. 文件不能以目录分隔符(斜杠)结尾
  3. 技术上有两个目录分隔符是平台特定的 - 即可能或不可以是斜线( Path.DirectorySeparatorCharPath.AltDirectorySeparatorChar

测试(Linqpad)

var paths = new[] {
    // exists
    @"C:\Temp\dir_test\folder_is_a_dir",
    @"C:\Temp\dir_test\is_a_dir_trailing_slash\",
    @"C:\Temp\dir_test\existing_folder_with.ext",
    @"C:\Temp\dir_test\file_thats_not_a_dir",
    @"C:\Temp\dir_test\notadir.txt",
    // doesn't exist
    @"C:\Temp\dir_test\dne_folder_is_a_dir",
    @"C:\Temp\dir_test\dne_folder_trailing_slash\",
    @"C:\Temp\dir_test\non_existing_folder_with.ext",
    @"C:\Temp\dir_test\dne_file_thats_not_a_dir",
    @"C:\Temp\dir_test\dne_notadir.txt",        
};

foreach(var path in paths) {
    IsFolder(path/*, false*/).Dump(path);
}

结果

C:\Temp\dir_test\folder_is_a_dir
  True 
C:\Temp\dir_test\is_a_dir_trailing_slash\
  True 
C:\Temp\dir_test\existing_folder_with.ext
  True 
C:\Temp\dir_test\file_thats_not_a_dir
  False 
C:\Temp\dir_test\notadir.txt
  False 
C:\Temp\dir_test\dne_folder_is_a_dir
  True 
C:\Temp\dir_test\dne_folder_trailing_slash\
  True 
C:\Temp\dir_test\non_existing_folder_with.ext
  False (this is the weird one)
C:\Temp\dir_test\dne_file_thats_not_a_dir
  True 
C:\Temp\dir_test\dne_notadir.txt
  False 

方法

/// <summary>
/// Whether the <paramref name="path"/> is a folder (existing or not); 
/// optionally assume that if it doesn't "look like" a file then it's a directory.
/// </summary>
/// <param name="path">Path to check</param>
/// <param name="assumeDneLookAlike">If the <paramref name="path"/> doesn't exist, does it at least look like a directory name?  As in, it doesn't look like a file.</param>
/// <returns><c>True</c> if a folder/directory, <c>false</c> if not.</returns>
public static bool IsFolder(string path, bool assumeDneLookAlike = true)
{
    // https://.com/questions/1395205/better-way-to-check-if-path-is-a-file-or-a-directory
    // turns out to be about the same as https://.com/a/19596821/1037948

    // check in order of verisimilitude

    // exists or ends with a directory separator -- files cannot end with directory separator, right?
    if (Directory.Exists(path)
        // use system values rather than assume slashes
        || path.EndsWith("" + Path.DirectorySeparatorChar)
        || path.EndsWith("" + Path.AltDirectorySeparatorChar))
        return true;

    // if we know for sure that it's an actual file...
    if (File.Exists(path))
        return false;

    // if it has an extension it should be a file, so vice versa
    // although technically directories can have extensions...
    if (!Path.HasExtension(path) && assumeDneLookAlike)
        return true;

    // only works for existing files, kinda redundant with `.Exists` above
    //if( File.GetAttributes(path).HasFlag(FileAttributes.Directory) ) ...; 

    // no idea -- could return an 'indeterminate' value (nullable bool)
    // or assume that if we don't know then it's not a folder
    return false;
}



这不会工作吗?

var isFile = Regex.IsMatch(path, @"\w{1,}\.\w{1,}$");



这是使用DirectoryInfo获取属性

Dim newnode As TreeNode
Dim dirs As New DirectoryInfo(node.FullPath)
For Each dir As DirectoryInfo In dirs.GetDirectories()
    If dir.Attributes = FileAttributes.Directory Then

    Else

    End If
Next

这将工作,如果你试图通过DirectoryInfo试图创建一个TreeView或阅读一个TreeView