c# - 当路径太长时，File.Exists() 错误地返回 false

Question

我目前正在开发一个遍历各种目录的程序，以确保使用 File.Exists() 存在特定文件。

应用程序一直声称某些文件不存在，而实际存在，我最近发现这个错误是由于路径太长造成的。

我知道有一些关于 SO 的问题可以解决 File.Exists() 返回不正确的值，但似乎没有一个可以解决这个特定问题。

重命名目录和文件以缩短路径并不是一个真正的选择，所以我现在不确定该怎么做。是否有解决此问题的变通方法？

正在使用的代码没什么特别的(我删除了一些不相关的代码)，但我会在下面包含它以防万一。

    private void checkFile(string path)
    {
        if (!File.Exists(path))
            Console.WriteLine("   *  File: " + path + " does not exist.");
    }

Answer 1

这很丑陋且效率低下，但它确实绕过了 MAX_PATH 限制:

const int MAX_PATH = 260;

private static void checkPath(string path)
{
    if (path.Length >= MAX_PATH)
    {
        checkFile_LongPath(path);
    }
    else if (!File.Exists(path))
    {
        Console.WriteLine("   *  File: " + path + " does not exist.");
    }
}

这里是 checkFile_LongPath 函数:

private static void checkFile_LongPath(string path)
{
    string[] subpaths = path.Split('\\');
    StringBuilder sbNewPath = new StringBuilder(subpaths[0]);
    // Build longest subpath that is less than MAX_PATH characters
    for (int i = 1; i < subpaths.Length; i++)
    {
        if (sbNewPath.Length + subpaths[i].Length >= MAX_PATH)
        {
            subpaths = subpaths.Skip(i).ToArray();
            break;
        }
        sbNewPath.Append("\\" + subpaths[i]);
    }
    DirectoryInfo dir = new DirectoryInfo(sbNewPath.ToString());
    bool foundMatch = dir.Exists;
    if (foundMatch)
    {
        // Make sure that all of the subdirectories in our path exist.
        // Skip the last entry in subpaths, since it is our filename.
        // If we try to specify the path in dir.GetDirectories(), 
        // We get a max path length error.
        int i = 0;
        while(i < subpaths.Length - 1 && foundMatch)
        {
            foundMatch = false;
            foreach (DirectoryInfo subDir in dir.GetDirectories())
            {
                if (subDir.Name == subpaths[i])
                {
                    // Move on to the next subDirectory
                    dir = subDir;
                    foundMatch = true;
                    break;
                }
            }
            i++;
        }
        if (foundMatch)
        {
            foundMatch = false;
            // Now that we've gone through all of the subpaths, see if our file exists.
            // Once again, If we try to specify the path in dir.GetFiles(), 
            // we get a max path length error.
            foreach (FileInfo fi in dir.GetFiles())
            {
                if (fi.Name == subpaths[subpaths.Length - 1])
                {
                    foundMatch = true;
                    break;
                }
            }
        }
    }
    // If we didn't find a match, write to the console.
    if (!foundMatch)
    {
        Console.WriteLine("   *  File: " + path + " does not exist.");
    }
}