我改变了监视目录中的文件的方式。我没有使用FileSystemWatcher，而是在另一个线程上轮询位置，然后查看文件的LastWriteTime。

DateTime lastWriteTime = File.GetLastWriteTime(someFilePath);

使用这些信息并保持文件路径的索引和最近的写入时间，我可以确定在特定位置已更改或已创建的文件。这使我摆脱了FileSystemWatcher的奇怪之处。主要的缺点是您需要一个数据结构来存储LastWriteTime和对文件的引用，但是它是可靠且易于实现的。

恐怕这是FileSystemWatcher类的一个众所周知的错误/特性。这是来自类的文档:

You may notice in certain situations that a single creation event generates multiple Created events that are handled by your component. For example, if you use a FileSystemWatcher component to monitor the creation of new files in a directory, and then test it by using Notepad to create a file, you may see two Created events generated even though only a single file was created. This is because Notepad performs multiple file system actions during the writing process. Notepad writes to the disk in batches that create the content of the file and then the file attributes. Other applications may perform in the same manner. Because FileSystemWatcher monitors the operating system activities, all events that these applications fire will be picked up.

现在这段文本是关于Created事件的，但同样的事情也适用于其他文件事件。在一些应用程序中，您可能能够通过使用NotifyFilter属性来解决这个问题，但我的经验是，有时您还必须进行一些手动重复过滤(hacks)。

前段时间我书签了一个页面，里面有一些FileSystemWatcher技巧。你可能会想去看看。

In my case need to get the last line of a text file that is inserted by other application, as soon as insertion is done. Here is my solution. When the first event is raised, i disable the watcher from raising others, then i call the timer TimeElapsedEvent because when my handle function OnChanged is called i need the size of the text file, but the size at that time is not the actual size, it is the size of the file imediatelly before the insertion. So i wait for a while to proceed with the right file size.

private FileSystemWatcher watcher = new FileSystemWatcher();
...
watcher.Path = "E:\\data";
watcher.NotifyFilter = NotifyFilters.LastWrite ;
watcher.Filter = "data.txt";
watcher.Changed += new FileSystemEventHandler(OnChanged);
watcher.EnableRaisingEvents = true;

...

private void OnChanged(object source, FileSystemEventArgs e)
   {
    System.Timers.Timer t = new System.Timers.Timer();
    try
    {
        watcher.Changed -= new FileSystemEventHandler(OnChanged);
        watcher.EnableRaisingEvents = false;

        t.Interval = 500;
        t.Elapsed += (sender, args) => t_Elapsed(sender, e);
        t.Start();
    }
    catch(Exception ex) {
        ;
    }
}

private void t_Elapsed(object sender, FileSystemEventArgs e) 
   {
    ((System.Timers.Timer)sender).Stop();
       //.. Do you stuff HERE ..
     watcher.Changed += new FileSystemEventHandler(OnChanged);
     watcher.EnableRaisingEvents = true;
}

我是这样处理双重创造问题的，忽略了第一个事件:

Private WithEvents fsw As New System.IO.FileSystemWatcher
Private complete As New List(Of String)

Private Sub fsw_Created(ByVal sender As Object, _
    ByVal e As System.IO.FileSystemEventArgs) Handles fsw.Created

    If Not complete.Contains(e.FullPath) Then
        complete.Add(e.FullPath)

    Else
        complete.Remove(e.FullPath)
        Dim th As New Threading.Thread(AddressOf hprocess)
        th.Start(e)

    End If

End Sub

我改变了监视目录中的文件的方式。我没有使用FileSystemWatcher，而是在另一个线程上轮询位置，然后查看文件的LastWriteTime。

DateTime lastWriteTime = File.GetLastWriteTime(someFilePath);

使用这些信息并保持文件路径的索引和最近的写入时间，我可以确定在特定位置已更改或已创建的文件。这使我摆脱了FileSystemWatcher的奇怪之处。主要的缺点是您需要一个数据结构来存储LastWriteTime和对文件的引用，但是它是可靠且易于实现的。

FileSystemWatcher中的任何重复的OnChanged事件都可以通过检查File来检测和丢弃。GetLastWriteTime文件的时间戳。像这样:

DateTime lastRead = DateTime.MinValue;

void OnChanged(object source, FileSystemEventArgs a)
{
    DateTime lastWriteTime = File.GetLastWriteTime(uri);
    if (lastWriteTime != lastRead)
    {
        doStuff();
        lastRead = lastWriteTime;
    }
    // else discard the (duplicated) OnChanged event
}