File.Delete the process cannot access the file because it is being used by another process

问题

public bool DownloadMp3File (DownloadedMp3 mp3) {
        WebClient client = new WebClient ();
        string filePath = "";
        bool wasDownload = false;
        try {


            string song = mp3.SongName;
            filePath = @"mp3\" + song + ".mp3";
            if (File.Exists (filePath)) {
                File.Delete (filePath);
            }

            DateTime tryCountNow = DateTime.Now;

            client = new WebClient ();
            client.DownloadFileAsync (new Uri (mp3.Url), filePath);
            client.DownloadProgressChanged += client_DownloadProgressChanged;
            client.DownloadFileCompleted += client_DownloadFileCompleted;
            DateTime start = DateTime.Now;
            bool notDownload = false;
            downloadComplete = false;
            while (!downloadComplete) {
                DateTime now = DateTime.Now;
                TimeSpan ts = now - start;
                int min = ts.Minutes;
                int sec = ts.Seconds;
                if (10 < sec && 0 == downloadProgress) {
                    notDownload = true;
                    client.CancelAsync ();
                    break;
                }
                if (min == 1) {
                    notDownload = true;
                    client.CancelAsync ();
                    break;
                }
                Thread.Sleep (30);
            }
            if (!notDownload) {
                client.CancelAsync ();
                client.OpenRead (mp3.Url);
                int downloadedFileSize = Convert.ToInt32 (client.ResponseHeaders["Content-Length"]);
                FileInfo localFile = new FileInfo (filePath);
                if (localFile.Length == downloadedFileSize) {
                    wasDownload = true;
                }
            }
        }
        catch {
            downloadProgress = 0;
            downloadComplete = false;
        }
        finally {
            client.CancelAsync ();
            client.Dispose ();
            downloadComplete = false;
            downloadProgress = 0;
            GC.Collect ();
            if (!wasDownload) {
                if (File.Exists (filePath)) {
                    FileSecurity fs = File.GetAccessControl (filePath);
                    File.Delete (filePath);
                }
            }
            Application.Current.Dispatcher.BeginInvoke (
            DispatcherPriority.Background,
            new Action (() =>
                MainWindow.label3.Content = ""
            ));
        }
        return wasDownload;
    }

Please help! I sometimes get that exception:

File.Delete the process cannot access the file because it is being used by another process

I can't find out why (I disposed WebClient).

回答1:

Your code suggests you're getting the "file being used" exception on a file that was newly downloaded. Many anti-virus programs automatically scan newly created and/or newly downloaded files, and may delay closing the file handle until the scan is done.

If that is your problem, then there's nothing more you can to do close the file on time. You can either switch to a different anti-virus that doesn't keep files locked during scans, or you can implement a delay+retry loop when trying to use a file that's recently been closed.

来源：https://stackoverflow.com/questions/26893737/file-delete-the-process-cannot-access-the-file-because-it-is-being-used-by-anoth