c# - 忽略 Directory.EnumerateFiles 的异常，跳过那些文件

Question

在枚举时我想跳过/忽略异常。

我尝试在选择器中添加一个 try catch:

static IEnumerable<string> GetSafeAllFiles
    (string path, string searchPattern, SearchOption searchOption = SearchOption.AllDirectories)
{
    return Directory.EnumerateFiles(path, searchPattern, searchOption)
                    .Select(f =>
                    {
                        try
                        {
                            return f;
                        }
                        catch (Exception e)
                        {
                            return string.Empty;
                        }
                    });
}

我尝试使用来自 accepted answer 的解决方案:

var test23 = Directory.EnumerateFiles(path, "*.*", SearchOption.AllDirectories)
                      .SkipExceptions().Take(100);

没有结果，因为它会在第一个错误后停止。所以我尝试实现我自己的:

static IEnumerable<string> test12(string path, string searchPattern, SearchOption searchOption = SearchOption.AllDirectories)
{
    if (string.IsNullOrEmpty(path))
    {
        throw new ArgumentNullException("path");
    }
    if (string.IsNullOrEmpty(searchPattern))
    {
        throw new ArgumentNullException("searchPattern");
    }

    Queue<string> stillToProcess = new Queue<string>(new[] { path });

    foreach (var dir in Directory.EnumerateDirectories(path))
    {
        stillToProcess.Enqueue(dir);
    }

    while (stillToProcess.Count > 0)
    {
        string currentPath = stillToProcess.Dequeue();
        IEnumerable<string> ret = Enumerable.Empty<string>();
        try
        {
            ret = Directory.EnumerateFiles(currentPath, searchPattern);
        }
        catch (UnauthorizedAccessException e)
        { }
                    // yield! keyword
        foreach (var i in ret) { yield return i; }
    }
    yield break;
}

但如果有一个错误，它会跳过目录。当我只想跳过错误文件时。

为了测试，可能的解决方案请在 c:\$Recycle.Bin 上进行，因为它是 UnauthorizedAccessException 的最简单来源。

Answer 1

这是我想出的:

public static IEnumerable<FileInfo> EnumerateFilesIgnoreErrors(IEnumerable<FileInfo> files)
{
    using (var e1 = files.GetEnumerator())
    {
        while (true)
        {
            FileInfo cur = null;

            try
            {
                // MoveNext() can throw an Exception
                if (! e1.MoveNext())
                    break;

                cur = e1.Current;

            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }

            if (cur != null)
            {
                yield return cur;
            }
        }
    }
}

像这样使用:

var myFiles = new DirectoryInfo(@"C:\")
           .EnumerateFiles("*", SearchOption.AllDirectories);
           
foreach (FileInfo fi in EnumerateFilesIgnoreErrors(myFiles))
{
    Debug.WriteLine(fi.Name);
} 

你也可以这样使用它:

var myList = EnumerateFilesIgnoreErrors(myFiles).ToList();

适用于“c:\$Recycle.Bin”等
忽略 UnauthorizedAccessException