通过C＃确定字符串是否是有效的文件路径

Question

我想知道如何确定字符串是否是有效的文件路径。

文件路径可能或可能是而不是存在。

Answer 1

路径的字符串格式的100％准确的检查是相当困难的，因为这将取决于文件系统上使用它（和网络协议，如果它不是在同一台计算机上）。

即使在windows甚至是NTFS中也不是那么简单，因为它依然依赖于.NET在后台使用的与内核通信的API。

而且，由于今天大多数文件系统支持Unicode，一个可能还需要检查所有的规则，正确地将编码的Unicode，规范化，等等等等

我今天准备先做一个只有一些基本的检查，那么一旦使用路径，就会正确处理异常。对于可能的规则请参见：

• Wikipedia - Filename的规则使用不同的文件系统
• Naming Files, Paths, and Namespaces窗户的具体规则

Answer 2

您可以使用FileInfo构造函数。如果“文件名为空，仅包含空白或包含无效字符，它将引发ArgumentException”。它也可以抛出SecurityException或UnauthorizedAccessException，如果你只关心格式，我认为你可以忽略它。

另一种选择是直接检查Path.GetInvalidPathChars。例如：

boolean possiblePath = pathString.IndexOfAny(Path.GetInvalidPathChars()) == -1; 

Answer 3

您是否尝试过正则表达式？

^([a-zA-Z]\:)(\\[^\\/:*?<>"|]*(?<![ ]))*(\.[a-zA-Z]{2,6})$ 

应该工作

Answer 4

我发现这个在regexlib.com（http://regexlib.com/REDetails.aspx?regexp_id=345）由梅德Borysov概述。

“文件名验证既证明了UNC（\服务器\共享\文件），并定期MS路径（C：\文件）”

^(([a-zA-Z]:|\\)\\)?(((\.)|(\.\.)|([^\\/:\*\?"\|<>\. ](([^\\/:\*\?"\|<>\. ])|([^\\/:\*\?"\|<>]*[^\\/:\*\?"\|<>\. ]))?))\\)*[^\\/:\*\?"\|<>\. ](([^\\/:\*\?"\|<>\. ])|([^\\/:\*\?"\|<>]*[^\\/:\*\?"\|<>\. ]))?$ 

与Regex.IsMatch运行它，你就会得到一个bool指示它是否有效。我认为正则表达式是要走的路，因为文件可能不存在。

Answer 5

静态类System.IO.Path可以做你要求的。

Answer 6

这里有一些东西，你可以使用：

• 检查，如果驱动器是正确的（例如一台计算机上的驱动器X：\存在，但不会对你的）：使用Path.IsPathRooted，看它是否是而不是相对路径，然后使用Environment.GetLogicalDrives()中的驱动器查看您的路径是否包含有效驱动器之一。
• 要检查有效字符，您有两种方法：Path.GetInvalidFileNameChars()和Path.GetInvalidPathChars()，它们不完全重叠。您还可以使用Path.GetDirectoryName(path)和Path.GetFileName(fileName)你输入名称，它将throw an exception如果

路径参数包含无效字符，为空，或者只包含空格。

Answer 7

直到尝试创建该文件时，才能真正确定。也许路径是有效的，但安全设置不允许创建文件。唯一可以告诉你路径是否真正有效的实例是操作系统，那么为什么不尝试创建该文件，赶上IOException，这表明事情真的发生了错误？ Imho这是更简单的方法：假设输入是有效的，并且如果它没有做什么，而不是做很多不必要的工作。

Answer 8

您可以简单地使用Path.Combine（）一个try catch语句里面：

string path = @" your path "; 
try 
{ 
    Path.Combine(path); 
} 
catch 
{ 
    MessageBox.Show("Invalid path"); 
} 

编辑： 需要注意的是，如果路径中包含通配符此功能不会抛出异常（ '*'和'？'），因为它们可以在搜索字符串中使用。

Answer 9

尝试使用此方法将尝试涵盖所有可能的异常情况。它几乎适用于所有与Windows相关的路径。

/// <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 10

Regex driveCheck = new Regex(@"^[a-zA-Z]:\\$"); 
     if (string.IsNullOrWhiteSpace(path) || path.Length < 3) 
     { 
     return false; 
     } 

     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 directoryInfo = new DirectoryInfo(Path.GetFullPath(path)); 
     try 
     { 
     if (!directoryInfo.Exists) 
     { 
      directoryInfo.Create(); 
     } 
     } 
     catch (Exception ex) 
     { 
     if (Log.IsErrorEnabled) 
     { 
      Log.Error(ex.Message); 
     } 
     return false; 
     }`enter code here` 

     return true; 
    }