检查字符串是否是有效的 Windows 目录（文件夹）路径

Question

我试图确定用户输入的字符串对于表示文件夹路径是否有效。我所说的有效是指格式正确。

在我的应用程序中，该文件夹代表安装目标。假设文件夹路径有效，我想确定该文件夹是否存在，如果不存在则创建它。

我目前正在使用 IO.Directory.Exists( String path ) 。我发现这工作正常，除非用户没有正确格式化字符串。当发生这种情况时，此方法将返回 false，表示该文件夹不存在。但这是一个问题，因为之后我将无法创建该文件夹。

从我的谷歌搜索中，我发现了一个使用正则表达式来检查格式是否正确的建议。我没有使用正则表达式的经验，想知道这是否是一种可行的方法。这是我发现的：

Regex r = new Regex( @"^(([a-zA-Z]\:)|(\\))(\\{1}|((\\{1})[^\\]([^/:*?<>""|]*))+)$" );
return r.IsMatch( path );

将正则表达式测试与 Directory.Exists() 结合使用，给我一个足够好的方法来检查路径是否有效以及是否存在？我知道这会因操作系统和其他因素而异，但该程序仅针对 Windows 用户。

Answer 1

调用 Path.GetFullPath;如果路径无效，它将抛出异常。

要禁止相对路径（例如 Word），请调用 Path.IsPathRooted。

Answer 2

我实际上不同意 SLAks。该解决方案对我不起作用。异常没有按预期发生。但这段代码对我有用：

if(System.IO.Directory.Exists(path))
{
    ...
}

Answer 3

Path.GetFullPath 仅给出以下例外

ArgumentException 路径是一个零长度字符串，仅包含白色
空格，或包含一个或多个定义在中的无效字符
获取无效路径字符。
- 或 - 系统无法检索绝对路径。

SecurityException 调用者没有所需的权限。

ArgumentNullException 路径为空。

NotSupportedException 路径包含不属于以下部分的冒号（“：”）
卷标识符（例如“c:\”）。

PathTooLongException 指定的路径、文件名或两者都超出
系统定义的最大长度。例如，在基于 Windows 的
平台、路径必须少于 248 个字符、文件名必须
少于 260 个字符。

另一种方法是使用以下方法：

/// <summary>
/// Validate the Path. If path is relative append the path to the project directory by default.
/// </summary>
/// <param name="path">Path to validate</param>
/// <param name="RelativePath">Relative path</param>
/// <param name="Extension">If want to check for File Path</param>
/// <returns></returns>
private static bool ValidateDllPath(ref string path, string RelativePath = "", string Extension = "")
{
    // Check if it contains any Invalid Characters.
    if (path.IndexOfAny(Path.GetInvalidPathChars()) == -1)
    {
        try
        {
            // If path is relative take %IGXLROOT% as the base directory
            if (!Path.IsPathRooted(path))
            {
                if (string.IsNullOrEmpty(RelativePath))
                {
                    // Exceptions handled by Path.GetFullPath
                    // ArgumentException path is a zero-length string, contains only white space, or contains one or more of the invalid characters defined in GetInvalidPathChars. -or- The system could not retrieve the absolute path.
                    // 
                    // SecurityException The caller does not have the required permissions.
                    // 
                    // ArgumentNullException path is null.
                    // 
                    // NotSupportedException path contains a colon (":") that is not part of a volume identifier (for example, "c:\"). 
                    // PathTooLongException The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.

                    // RelativePath is not passed so we would take the project path 
                    path = Path.GetFullPath(RelativePath);

                }
                else
                {
                    // Make sure the path is relative to the RelativePath and not our project directory
                    path = Path.Combine(RelativePath, path);
                }
            }

            // Exceptions from FileInfo Constructor:
            //   System.ArgumentNullException:
            //     fileName is null.
            //
            //   System.Security.SecurityException:
            //     The caller does not have the required permission.
            //
            //   System.ArgumentException:
            //     The file name is empty, contains only white spaces, or contains invalid characters.
            //
            //   System.IO.PathTooLongException:
            //     The specified path, file name, or both exceed the system-defined maximum
            //     length. For example, on Windows-based platforms, paths must be less than
            //     248 characters, and file names must be less than 260 characters.
            //
            //   System.NotSupportedException:
            //     fileName contains a colon (:) in the middle of the string.
            FileInfo fileInfo = new FileInfo(path);

            // Exceptions using FileInfo.Length:
            //   System.IO.IOException:
            //     System.IO.FileSystemInfo.Refresh() cannot update the state of the file or
            //     directory.
            //
            //   System.IO.FileNotFoundException:
            //     The file does not exist.-or- The Length property is called for a directory.
            bool throwEx = fileInfo.Length == -1;

            // Exceptions using FileInfo.IsReadOnly:
            //   System.UnauthorizedAccessException:
            //     Access to fileName is denied.
            //     The file described by the current System.IO.FileInfo object is read-only.-or-
            //     This operation is not supported on the current platform.-or- The caller does
            //     not have the required permission.
            throwEx = fileInfo.IsReadOnly;

            if (!string.IsNullOrEmpty(Extension))
            {
                // Validate the Extension of the file.
                if (Path.GetExtension(path).Equals(Extension, StringComparison.InvariantCultureIgnoreCase))
                {
                    // Trim the Library Path
                    path = path.Trim();
                    return true;
                }
                else
                {
                    return false;
                }
            }
            else
            {
                return true;

            }
        }
        catch (ArgumentNullException)
        {
            //   System.ArgumentNullException:
            //     fileName is null.
        }
        catch (System.Security.SecurityException)
        {
            //   System.Security.SecurityException:
            //     The caller does not have the required permission.
        }
        catch (ArgumentException)
        {
            //   System.ArgumentException:
            //     The file name is empty, contains only white spaces, or contains invalid characters.
        }
        catch (UnauthorizedAccessException)
        {
            //   System.UnauthorizedAccessException:
            //     Access to fileName is denied.
        }
        catch (PathTooLongException)
        {
            //   System.IO.PathTooLongException:
            //     The specified path, file name, or both exceed the system-defined maximum
            //     length. For example, on Windows-based platforms, paths must be less than
            //     248 characters, and file names must be less than 260 characters.
        }
        catch (NotSupportedException)
        {
            //   System.NotSupportedException:
            //     fileName contains a colon (:) in the middle of the string.
        }
        catch (FileNotFoundException)
        {
            // System.FileNotFoundException
            //  The exception that is thrown when an attempt to access a file that does not
            //  exist on disk fails.
        }
        catch (IOException)
        {
            //   System.IO.IOException:
            //     An I/O error occurred while opening the file.
        }
        catch (Exception)
        {
            // Unknown Exception. Might be due to wrong case or nulll checks.
        }
    }
    else
    {
        // Path contains invalid characters
    }
    return false;
}

Answer 4

这是一个利用 Path.GetFullPath 按照@SLaks的答案中的建议。

在我在这里包含的代码中，请注意 IsValidPath(string path) 的设计使得调用者不必担心异常处理。

您可能还会发现，当您希望安全地尝试获取绝对路径时，它调用的方法 TryGetFullPath(...) 也有其自身的优点。

/// <summary>
/// Gets a value that indicates whether <paramref name="path"/>
/// is a valid path.
/// </summary>
/// <returns>Returns <c>true</c> if <paramref name="path"/> is a
/// valid path; <c>false</c> otherwise. Also returns <c>false</c> if
/// the caller does not have the required permissions to access
/// <paramref name="path"/>.
/// </returns>
/// <seealso cref="Path.GetFullPath"/>
/// <seealso cref="TryGetFullPath"/>
public static bool IsValidPath(string path)
{
    string result;
    return TryGetFullPath(path, out result);
}

/// <summary>
/// Returns the absolute path for the specified path string. A return
/// value indicates whether the conversion succeeded.
/// </summary>
/// <param name="path">The file or directory for which to obtain absolute
/// path information.
/// </param>
/// <param name="result">When this method returns, contains the absolute
/// path representation of <paramref name="path"/>, if the conversion
/// succeeded, or <see cref="String.Empty"/> if the conversion failed.
/// The conversion fails if <paramref name="path"/> is null or
/// <see cref="String.Empty"/>, or is not of the correct format. This
/// parameter is passed uninitialized; any value originally supplied
/// in <paramref name="result"/> will be overwritten.
/// </param>
/// <returns><c>true</c> if <paramref name="path"/> was converted
/// to an absolute path successfully; otherwise, false.
/// </returns>
/// <seealso cref="Path.GetFullPath"/>
/// <seealso cref="IsValidPath"/>
public static bool TryGetFullPath(string path, out string result)
{
    result = String.Empty;
    if (String.IsNullOrWhiteSpace(path)) { return false; }
    bool status = false;

    try
    {
        result = Path.GetFullPath(path);
        status = true;
    }
    catch (ArgumentException) { }
    catch (SecurityException) { }
    catch (NotSupportedException) { }
    catch (PathTooLongException) { }

    return status;
}

Answer 5

    private bool IsValidPath(string path)
    {
        Regex driveCheck = new Regex(@"^[a-zA-Z]:\\$");
        if (!driveCheck.IsMatch(path.Substring(0, 3))) return false;
        string strTheseAreInvalidFileNameChars = new string(Path.GetInvalidPathChars());
        strTheseAreInvalidFileNameChars += @":/?*" + "\"";
        Regex containsABadCharacter = new Regex("[" + Regex.Escape(strTheseAreInvalidFileNameChars) + "]");
        if (containsABadCharacter.IsMatch(path.Substring(3, path.Length - 3)))
            return false;

        DirectoryInfo dir = new DirectoryInfo(Path.GetFullPath(path));
        if (!dir.Exists)
            dir.Create();
        return true;
    }

Answer 6

使用此代码

string DirectoryName = "Sample Name For Directory Or File";
Path.GetInvalidFileNameChars()
  .Where(x => DirectoryName.Contains(x))
  .Count() > 0 || DirectoryName == "con"

Answer 7

一个更简单的独立于操作系统的解决方案：

继续尝试创建实际目录； 如果出现问题或名称无效，操作系统将自动抱怨并且代码将抛出。

public static class PathHelper
{
    public static void ValidatePath(string path)
    {
        if (!Directory.Exists(path))
            Directory.CreateDirectory(path).Delete();
    }
}

用法：

try
{
    PathHelper.ValidatePath(path);
}
catch(Exception e)
{
    // handle exception
}

Directory.CreateDirectory() 将自动抛出以下所有情况：

系统.IO.IOException：
path指定的目录是一个文件。
- 或 - 网络名称未知。

系统.UnauthorizedAccessException：
调用者没有
需要许可。

系统参数异常：
路径是一个零长度字符串，包含
仅空白，或包含一个或多个无效字符。你
可以通过使用查询无效字符
System.IO.Path.GetInvalidPathChars 方法。 - 或 - 路径有前缀
仅带有或包含冒号字符 (:)。

System.ArgumentNullException：
路径为空。

System.IO.PathTooLongException：
指定的路径、文件名或
都超出了系统定义的最大长度。

System.IO.DirectoryNotFoundException：
指定的路径无效
（例如，它位于未映射的驱动器上）。

系统.NotSupportedException：
路径包含冒号字符 (:)
它不是驱动器标签（“C:”）的一部分。

Answer 8

我对这段代码没有任何问题：

private bool IsValidPath(string path, bool exactPath = true)
{
    bool isValid = true;

    try
    {
        string fullPath = Path.GetFullPath(path);

        if (exactPath)
        {
            string root = Path.GetPathRoot(path);
            isValid = string.IsNullOrEmpty(root.Trim(new char[] { '\\', '/' })) == false;
        }
        else
        {
            isValid = Path.IsPathRooted(path);
        }
    }
    catch(Exception ex)
    {
        isValid = false;
    }

    return isValid;
}

例如，这些将返回 false：

IsValidPath("C:/abc*d");
IsValidPath("C:/abc?d");
IsValidPath("C:/abc\"d");
IsValidPath("C:/abc<d");
IsValidPath("C:/abc>d");
IsValidPath("C:/abc|d");
IsValidPath("C:/abc:d");
IsValidPath("");
IsValidPath("./abc");
IsValidPath("/abc");
IsValidPath("abc");
IsValidPath("abc", false);

这些将返回 true：

IsValidPath(@"C:\\abc");
IsValidPath(@"F:\FILES\");
IsValidPath(@"C:\\abc.docx\\defg.docx");
IsValidPath(@"C:/abc/defg");
IsValidPath(@"C:\\\//\/\\/\\\/abc/\/\/\/\///\\\//\defg");
IsValidPath(@"C:/abc/def~`!@#$%^&()_-+={[}];',.g");
IsValidPath(@"C:\\\\\abc////////defg");
IsValidPath(@"/abc", false);