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如何使用FileSystemWatcher监视一个目录并允许它被正确删除?

filesystemwatcher .net c#

HHK · 技术社区 · 16 年前

string dir = Environment.CurrentDirectory + @"\a";
Directory.CreateDirectory(dir);
FileSystemWatcher watcher = new FileSystemWatcher(dir);
watcher.IncludeSubdirectories = false;
watcher.EnableRaisingEvents = true;
Console.WriteLine("Deleting " + dir);
Directory.Delete(dir, true);
if (Directory.Exists(dir))
{
    Console.WriteLine("Getting dirs of " + dir);
    Directory.GetDirectories(dir);
}
Console.ReadLine();

有趣的是,这会引发一个UnauthorizedAccessException Directory.GetDirectories(dir) .

删除监视的目录将返回无错误的结果,但是Directory.Exists()仍然返回true,并且目录仍然列出。此外,访问目录会导致任何程序的“访问被拒绝”。一旦带有FileSystemWatcher的.NET应用程序退出,目录就会消失。

4 回复 | 直到 16 年前

Hans Passant 16 年前

文件也存在相同的机制。复习FileShare.Delete

MTs 16 年前

 if (new DirectoryInfo(dir).Exists)

而不是:

if (Directory.Exists(dir))

VSOP_juDGe 14 年前

    var dir = new DirectoryInfo(path);
    // delete dir in explorer
    System.Diagnostics.Debug.Assert(dir.Exists); // true
    dir.Refresh();
    System.Diagnostics.Debug.Assert(!dir.Exists); // false

Chris Goldsmith 11 年前

不幸的是,FileSystemWatcher获取了目录的句柄,这意味着当目录被删除时,仍然有一个被标记为挂起删除的目录的句柄。我尝试了一些实验,似乎可以使用FileSystemWatcher中的错误事件处理程序来识别何时发生这种情况。

    public myClass(String dir)
    {
        mDir = dir;
        Directory.CreateDirectory(mDir);

        InitFileSystemWatcher();

        Console.WriteLine("Deleting " + mDir);
        Directory.Delete(mDir, true);
    }
    private FileSystemWatcher watcher;

    private string mDir;

    private void MyErrorHandler(object sender, FileSystemEventArgs args)
    {
        // You can try to recreate the FileSystemWatcher here
        try
        {
            mWatcher.Error -= MyErrorHandler;
            mWatcher.Dispose();
            InitFileSystemWatcher();
        }
        catch (Exception)
        {
            // a bit nasty catching Exception, but you can't do much
            // but the handle should be released now 
        }
        // you might not be able to check immediately as your old FileSystemWatcher
        // is in your current callstack, but it's a start.
    }

    private void InitFileSystemWatcher()
    {
        mWatcher = new FileSystemWatcher(mDir);
        mWatcher.IncludeSubdirectories = false;
        mWatcher.EnableRaisingEvents = true;
        mWatcher.Error += MyErrorHandler;
    }

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