我正在尝试使用以下代码枚举计算机上的文件，但每次遇到我无权读取的文件或目录时都会引发异常。抛出异常后有什么方法可以继续搜索吗？我知道有些人遇到过类似的问题，但除了单独检查每个文件/文件夹之外，还有其他方法吗？
try
{
string[] files = Directory.GetFiles(@"C:\", *.*",SearchOption.AllDirectories);
foreach (string file in files)
{
Console.WriteLine(file);
}
}
catch
{
}
感谢您的帮助，因为这让我发疯了！
【问题讨论】：
这里是一些基于 Windows API 的实用程序代码，它枚举文件系统条目而不抛出/捕获异常。
示例用法：
...
foreach (var fi in Utilities.EnumerateFileSystemEntries(@"c:\windows\system32", DirectoryEnumerateOptions.Recursive))
{
Console.WriteLine(fi.FullName);
}
...
实用类：
[Flags]
public enum DirectoryEnumerateOptions
{
None = 0x0,
Recursive = 0x1,
ThrowErrors = 0x2, // if you really want it
ExpandEnvironmentVariables = 0x4,
}
public static class Utilities
{
public static IEnumerable<FileSystemInfo> EnumerateFileSystemEntries(string directoryPath, DirectoryEnumerateOptions options = DirectoryEnumerateOptions.None)
{
if (directoryPath == null)
throw new ArgumentNullException(nameof(directoryPath));
if (!Path.IsPathRooted(directoryPath))
{
directoryPath = Path.GetFullPath(directoryPath);
}
return EnumerateFileSystemEntriesPrivate(directoryPath, options);
}
private static IEnumerable<FileSystemInfo> EnumerateFileSystemEntriesPrivate(string directoryPath, DirectoryEnumerateOptions options = DirectoryEnumerateOptions.None)
{
if (!Directory.Exists(directoryPath))
yield break;
var findPath = Normalize(directoryPath, options.HasFlag(DirectoryEnumerateOptions.ExpandEnvironmentVariables));
if (!findPath.EndsWith("*"))
{
findPath = Path.Combine(findPath, "*");
}
var h = FindFirstFile(findPath, out var data);
if (h == INVALID_HANDLE_VALUE)
{
if (options.HasFlag(DirectoryEnumerateOptions.ThrowErrors))
throw new Win32Exception(Marshal.GetLastWin32Error());
yield break;
}
if (Include(ref data))
{
yield return ToInfo(ref data, directoryPath);
if (options.HasFlag(DirectoryEnumerateOptions.Recursive) && data.fileAttributes.HasFlag(FileAttributes.Directory))
{
foreach (var wfd in EnumerateFileSystemEntriesPrivate(Path.Combine(directoryPath, data.cFileName), options))
{
yield return wfd;
}
}
}
do
{
if (!FindNextFile(h, out data))
{
if (Marshal.GetLastWin32Error() == ERROR_NO_MORE_FILES)
{
FindClose(h);
break;
}
continue;
}
if (Include(ref data))
{
yield return ToInfo(ref data, directoryPath);
if (options.HasFlag(DirectoryEnumerateOptions.Recursive) && data.fileAttributes.HasFlag(FileAttributes.Directory))
{
foreach (var wfd in EnumerateFileSystemEntriesPrivate(Path.Combine(directoryPath, data.cFileName), options))
{
yield return wfd;
}
}
}
}
while (true);
}
private static bool Include(ref WIN32_FIND_DATA data) => data.cFileName != "." && data.cFileName != "..";
private static FileSystemInfo ToInfo(ref WIN32_FIND_DATA data, string directoryPath)
{
if (data.fileAttributes.HasFlag(FileAttributes.Directory))
return new FileInfo(Path.Combine(directoryPath, data.cFileName));
return new DirectoryInfo(Path.Combine(directoryPath, data.cFileName));
}
private static string Normalize(string path, bool expandEnvironmentVariables)
{
if (path == null)
return null;
string expanded;
if (expandEnvironmentVariables)
{
expanded = Environment.ExpandEnvironmentVariables(path);
}
else
{
expanded = path;
}
if (expanded.StartsWith(_prefix))
return expanded;
if (expanded.StartsWith(@"\\"))
return _uncPrefix + expanded.Substring(2);
return _prefix + expanded;
}
[DllImport("kernel32", SetLastError = true, CharSet = CharSet.Unicode)]
private static extern IntPtr FindFirstFile(string lpFileName, out WIN32_FIND_DATA lpFindFileData);
[DllImport("kernel32", SetLastError = true)]
private static extern bool FindClose(IntPtr hFindFile);
[DllImport("kernel32", SetLastError = true, CharSet = CharSet.Unicode)]
private static extern bool FindNextFile(IntPtr hFindFile, out WIN32_FIND_DATA lpFindFileData);
#pragma warning disable IDE1006 // Naming Styles
private const int ERROR_NO_MORE_FILES = 18;
private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
#pragma warning restore IDE1006 // Naming Styles
private const string _prefix = @"\\?\";
private const string _uncPrefix = _prefix + @"UNC\";
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
internal struct WIN32_FIND_DATA
{
public FileAttributes fileAttributes;
public uint ftCreationTimeLow;
public uint ftCreationTimeHigh;
public uint ftLastAccessTimeLow;
public uint ftLastAccessTimeHigh;
public uint ftLastWriteTimeLow;
public uint ftLastWriteTimeHigh;
public uint fileSizeHigh;
public uint fileSizeLow;
public uint dwReserved0;
public uint dwReserved1;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string cFileName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
public string cAlternateFileName;
}
}
【讨论】：
我今天遇到了同样的问题。我一起破解了以下代码。如果您想在实际产品中使用它，您可能需要改进错误处理。因为这是一个一次性脚本，所以我不太在意。
static IEnumerable<string> EnumerateFilesRecursive(string root,string pattern="*")
{
var todo = new Queue<string>();
todo.Enqueue(root);
while (todo.Count > 0)
{
string dir = todo.Dequeue();
string[] subdirs = new string[0];
string[] files = new string[0];
try
{
subdirs = Directory.GetDirectories(dir);
files = Directory.GetFiles(dir, pattern);
}
catch (IOException)
{
}
catch (System.UnauthorizedAccessException)
{
}
foreach (string subdir in subdirs)
{
todo.Enqueue(subdir);
}
foreach (string filename in files)
{
yield return filename;
}
}
}
要使用它，您可以：
string[] files = EnumerateFilesRecursive(@"C:\").ToArray();//Note the ToArray()
foreach (string file in files)
{
Console.WriteLine(file);
}
它首先枚举所有文件，将所有文件名存储在内存中，然后才显示它们。或者，您可以：
IEnumerable<string> files = EnumerateFilesRecursive(@"C:\");//Note that there is NO ToArray()
foreach (string file in files)
{
Console.WriteLine(file);
}
枚举时写入，因此不需要将所有文件名同时保存在内存中。
【讨论】：