对多个文件使用 FileSystemWatcher

Question

我想使用 FileSystemWatcher 来监视目录及其子目录中移动的文件。然后我想在所有文件都被移动后触发一些代码。但我不知道怎么做。我的代码会在每次移动文件时触发，如果用户一次移动多个文件，我只希望它为所有文件触发一次。所以基本上我想创建一个列表，一旦完成所有文件的移动，我想对该列表做一些事情......

代码如下：

class Monitor
{
    private List<string> _filePaths;  
    public void CreateWatcher(string path)
    {
        FileSystemWatcher watcher = new FileSystemWatcher();

        watcher.Filter = "*.*";

        watcher.Created += new
        FileSystemEventHandler(watcher_FileCreated);

        watcher.Path = path;
        watcher.IncludeSubdirectories = true;

        watcher.EnableRaisingEvents = true;
    }

    void watcher_FileCreated(object sender, FileSystemEventArgs e)
    {
        _filePaths.Add(e.FullPath);
        Console.WriteLine("Files have been created or moved!");
    }

}

更新：尝试使用 Chris 的代码，但它不起作用（请参阅我在 Chris 的回答中的评论）：

class Monitor
    {
        private List<string> _filePaths;
        private Timer _notificationTimer;
        private FileSystemWatcher _fsw;
        public Monitor(string path)
        {
            _notificationTimer = new Timer();
            _notificationTimer.Elapsed += notificationTimer_Elapsed;
            // CooldownSeconds is the number of seconds the Timer is 'extended' each time a file is added.
            // I found it convenient to put this value in an app config file.
            int CooldownSeconds = 1;
            _notificationTimer.Interval = CooldownSeconds * 1000;

            _fsw = new FileSystemWatcher();
            _fsw.Path = path;
            _fsw.IncludeSubdirectories = true;
            _fsw.EnableRaisingEvents = true;

            // Set up the particulars of your FileSystemWatcher.
            _fsw.Created += fsw_Created;
        }

        private void notificationTimer_Elapsed(object sender, ElapsedEventArgs e)
        {
            //
            // Do what you want to do with your List of files.
            //
            Console.Write("Done");
            // Stop the timer and wait for the next batch of files.            
            _notificationTimer.Stop();
            // Clear your file List.
            _filePaths = new List<string>();
        }


        // Fires when a file is created.
        private void fsw_Created(object sender, FileSystemEventArgs e)
        {
            // Add to our List of files.
            _filePaths.Add(e.Name);

            // 'Reset' timer.
            _notificationTimer.Stop();
            _notificationTimer.Start();
        }


    }

更新 2：

根据安德斯的回答试过这个：

public class FileListEventArgs : EventArgs
{
    public List<string> FileList { get; set; }
}

public class Monitor
{
    private List<string> filePaths;
    private ReaderWriterLockSlim rwlock;
    private Timer processTimer;
    public event EventHandler FileListCreated;


    public void OnFileListCreated(FileListEventArgs e)
    {
        if (FileListCreated != null)
            FileListCreated(this, e);
    }

    public Monitor(string path)
    {
        filePaths = new List<string>();

        rwlock = new ReaderWriterLockSlim();

        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.Filter = "*.*";
        watcher.Created += watcher_FileCreated;

        watcher.Path = path;
        watcher.IncludeSubdirectories = true;
        watcher.EnableRaisingEvents = true;
    }

    private void ProcessQueue()
    {
        List<string> list = new List<string>();
        try
        {
            Console.WriteLine("Processing queue, " + filePaths.Count + " files created:");
            rwlock.EnterReadLock();

        }
        finally
        {
            if (processTimer != null)
            {
                processTimer.Stop();
                processTimer.Dispose();
                processTimer = null;
                OnFileListCreated(new FileListEventArgs { FileList = filePaths });
                filePaths.Clear();
            }
            rwlock.ExitReadLock();
        }
    }

    void watcher_FileCreated(object sender, FileSystemEventArgs e)
    {
        try
        {
            rwlock.EnterWriteLock();
            filePaths.Add(e.FullPath);

            if (processTimer == null)
            {
                // First file, start timer.
                processTimer = new Timer(2000);
                processTimer.Elapsed += (o, ee) => ProcessQueue();
                processTimer.Start();
            }
            else
            {
                // Subsequent file, reset timer. 
                processTimer.Stop();
                processTimer.Start();
            }

        }
        finally
        {
            rwlock.ExitWriteLock();
        }
    }

我不得不将事件触发器移到 finally 语句中，这很有效。我不知道是否有什么理由我不想这样做？

Answer 1

正如 Jay 所说：计时器可能是“分组”事件的唯一方法。锁可能有点矫枉过正，但我​​不喜欢在多线程情况下改变集合的想法（我认为来自 fswatcher 的事件是在池中的线​​程上调用的）。

  public class Monitor : IDisposable
  {
     private List<string> filePaths;
     private ReaderWriterLockSlim rwlock;
     private Timer processTimer;
     private string watchedPath;
     private FileSystemWatcher watcher;

     public Monitor(string watchedPath)
     {
        filePaths = new List<string>();

        rwlock = new ReaderWriterLockSlim();

        this.watchedPath = watchedPath;
        InitFileSystemWatcher();
     }

     private void InitFileSystemWatcher()
     {
        watcher = new FileSystemWatcher();
        watcher.Filter = "*.*";
        watcher.Created += Watcher_FileCreated;
        watcher.Error += Watcher_Error;
        watcher.Path = watchedPath;
        watcher.IncludeSubdirectories = true;
        watcher.EnableRaisingEvents = true;
     }

     private void Watcher_Error(object sender, ErrorEventArgs e)
     {
        // Watcher crashed. Re-init.
        InitFileSystemWatcher();
     }

     private void Watcher_FileCreated(object sender, FileSystemEventArgs e)
     {
        try
        {
           rwlock.EnterWriteLock();
           filePaths.Add(e.FullPath);

           if (processTimer == null)
           {
              // First file, start timer.
              processTimer = new Timer(2000);
              processTimer.Elapsed += ProcessQueue;
              processTimer.Start();
           }
           else
           {
              // Subsequent file, reset timer.
              processTimer.Stop();
              processTimer.Start();
           }

        }
        finally
        {
           rwlock.ExitWriteLock();
        }
     }

     private void ProcessQueue(object sender, ElapsedEventArgs args)
     {
        try
        {
           Console.WriteLine("Processing queue, " + filePaths.Count + " files created:");
           rwlock.EnterReadLock();
           foreach (string filePath in filePaths)
           {
              Console.WriteLine(filePath);
           }
           filePaths.Clear();
        }
        finally
        {
           if (processTimer != null)
           {
              processTimer.Stop();
              processTimer.Dispose();
              processTimer = null;
           }
           rwlock.ExitReadLock();
        }
     }

     protected virtual void Dispose(bool disposing)
     {
        if (disposing)
        {
           if (rwlock != null)
           {
              rwlock.Dispose();
              rwlock = null;
           }
           if (watcher != null)
           {
              watcher.EnableRaisingEvents = false;
              watcher.Dispose();
              watcher = null;
           }
        }
     }

     public void Dispose()
     {
        Dispose(true);
        GC.SuppressFinalize(this);
     }

  }     

记得在 fswatcher 上设置缓冲区大小，并在 fswatcher 出现错误时实现“复活”（即将错误事件绑定到重新创建 watcher 的方法）。

编辑：注意，本例中的计时器是 System.Timers.Timer，而不是 System.Threading.Timer

编辑：现在包含观察者的错误处理，处置逻辑。

Answer 2

我必须做同样的事情。在 Monitor 类中使用 System.Timers.Timer 并对其 Elapsed 事件进行编码以处理您的文件列表并清除列表。当通过 FSW 事件将第一项添加到文件列表中时，启动计时器。当后续项目添加到列表中时，通过停止并重新启动计时器来“重置”计时器。

类似这样的：

class Monitor
{
    FileSystemWatcher _fsw;
    Timer _notificationTimer;
    List<string> _filePaths = new List<string>();

    public Monitor() {
        _notificationTimer = new Timer();
        _notificationTimer.Elapsed += notificationTimer_Elapsed;
        // CooldownSeconds is the number of seconds the Timer is 'extended' each time a file is added.
        // I found it convenient to put this value in an app config file.
        _notificationTimer.Interval = CooldownSeconds * 1000;

        _fsw = new FileSystemWatcher();
        // Set up the particulars of your FileSystemWatcher.
        _fsw.Created += fsw_Created;
    }

    private void notificationTimer_Elapsed(object sender, ElapsedEventArgs e) {
        //
        // Do what you want to do with your List of files.
        //

        // Stop the timer and wait for the next batch of files.            
        _notificationTimer.Stop();
        // Clear your file List.
        _filePaths = new List<string>();
    }


    // Fires when a file is created.
    private void fsw_Created(object sender, FileSystemEventArgs e) {
        // Add to our List of files.
        _filePaths.Add(e.Name);

        // 'Reset' timer.
        _notificationTimer.Stop();
        _notificationTimer.Start();
    }
}

Answer 3

Rx - 油门 - 让这项工作变得简单。这是一个可测试、可重复使用的解决方案。

public class Files
{
     public static FileSystemWatcher WatchForChanges(string path, string filter, Action triggeredAction)
            {
                var monitor = new FileSystemWatcher(path, filter);

                //monitor.NotifyFilter = NotifyFilters.FileName;
                monitor.Changed += (o, e) => triggeredAction.Invoke();
                monitor.Created += (o, e) => triggeredAction.Invoke();
                monitor.Renamed += (o, e) => triggeredAction.Invoke();
                monitor.EnableRaisingEvents = true;

                return monitor;
            }
}

让我们将事件合并到一个序列中

  public IObservable<Unit> OnUpdate(string path, string pattern)
        {
            return Observable.Create<Unit>(o =>
            {
                var watcher = Files.WatchForChanges(path, pattern, () => o.OnNext(new Unit()));

                return watcher;
            });
        }

最后是用法

OnUpdate(path, "*.*").Throttle(Timespan.FromSeconds(10)).Subscribe(this, _ => DoWork())

您显然可以根据自己的需要调整油门速度。

Answer 4

另外，将缓冲区大小设置为大于默认值以避免缓冲区溢出。当超过 25 个文件被放入源目录（在我的测试中）时，就会发生这种情况。如果删除了 200 个文件，则仅对少数文件调用事件处理程序，而不是全部。

_watcher.InternalBufferSize = 65536; //最大缓冲区大小