FileSystemWatcher Changed事件被引发两次

我有一个应用程序，我正在寻找一个文本文件，如果对文件做了任何更改，我使用OnChanged事件处理程序来处理事件。我正在使用NotifyFilters。LastWriteTime，但是事件仍然被触发两次。这是代码。

public void Initialize()
{
   FileSystemWatcher _fileWatcher = new FileSystemWatcher();
  _fileWatcher.Path = "C:\\Folder";
  _fileWatcher.NotifyFilter = NotifyFilters.LastWrite;
  _fileWatcher.Filter = "Version.txt";
  _fileWatcher.Changed += new FileSystemEventHandler(OnChanged);
  _fileWatcher.EnableRaisingEvents = true;
}

private void OnChanged(object source, FileSystemEventArgs e)
{
   .......
}

在我的情况下，OnChanged被调用两次，当我改变文本文件version.txt并保存它。

当前回答

这个代码对我有用。

        private void OnChanged(object source, FileSystemEventArgs e)
    {

        string fullFilePath = e.FullPath.ToString();
        string fullURL = buildTheUrlFromStudyXML(fullFilePath);

        System.Diagnostics.Process.Start("iexplore", fullURL);

        Timer timer = new Timer();
        ((FileSystemWatcher)source).Changed -= new FileSystemEventHandler(OnChanged);
        timer.Interval = 1000;
        timer.Elapsed += new ElapsedEventHandler(t_Elapsed);
        timer.Start();
    }

    private void t_Elapsed(object sender, ElapsedEventArgs e)
    {
        ((Timer)sender).Stop();
        theWatcher.Changed += new FileSystemEventHandler(OnChanged);
    }

2016-09-14 11:59:20

其他回答

我在此将这段代码遗赠后人:

    static DateTimeOffset lastChanged = DateTimeOffset.UtcNow;
        static string lastChangedFile = null;

...

        private static void OnChanged(object sender, FileSystemEventArgs e)
        {
            if (e.ChangeType != WatcherChangeTypes.Changed || 
                (lastChanged.AddMilliseconds(500) > DateTimeOffset.UtcNow && lastChangedFile == e.FullPath)
               ) 
            {
                return;
            }
            lastChanged = DateTimeOffset.UtcNow;
            lastChangedFile = e.FullPath;
            Console.WriteLine($"Changed: {e.FullPath}");
            
        }

2022-05-27 12:52:15

一个可能的“黑客”是使用响应式扩展来限制事件，例如:

var watcher = new FileSystemWatcher("./");

Observable.FromEventPattern<FileSystemEventArgs>(watcher, "Changed")
            .Throttle(new TimeSpan(500000))
            .Subscribe(HandleChangeEvent);

watcher.EnableRaisingEvents = true;

在本例中，我将设置为50ms，在我的系统上这就足够了，但更高的值应该更安全。(就像我说的，这仍然是一个“hack”)。

2014-02-10 06:54:06

一直在寻找答案，但我想到了一个肮脏的解决方案。因为我的事件触发了两次，所以第二个动作什么也不做。

       $count = 1
       $action = { 
            if($count -eq 1){                  
                #DO SOMETHING
                $count = 2 
            }else{
                $count = 1
            }
        }

2019-11-20 06:50:45

以下是我的解决方案，帮助我阻止事件被提出两次:

watcher.NotifyFilter = NotifyFilters.FileName | NotifyFilters.Size;

这里我只设置了文件名和大小的NotifyFilter属性。 watcher是FileSystemWatcher的对象。希望这能有所帮助。

2011-11-21 08:11:32

代码可自定义禁用阻止第二个观察者升起的时间间隔，如果他们存在，则不阻止观察者:

    namespace Watcher
    {
        class Static
        {
            public static DateTime lastDomain { get; set; }
            public static string lastDomainStr { get; set; }
        }
        public partial class Form1 : Form
       {
            int minMs = 20;//time for blocking in ms
            public Form1()
            {
                InitializeComponent();
                Static.lastDomain = new DateTime(1970, 1, 1, 0, 0, 0);
                Static.lastDomainStr = "";  
                Start();
            }
             private void Start()//Start watcher
             {
                //...
                domain.Changed += new FileSystemEventHandler(Domain);
                domain.EnableRaisingEvents = true;
                //...you second unblocked watchers
                second.Changed += new FileSystemEventHandler(Second);
                second.EnableRaisingEvents = true;
             }
             private void Domain(object source, FileSystemEventArgs e)
             {
                if (now.Subtract(Static.lastDomain).TotalMilliseconds < minMs && Static.lastDomainStr == e.FullPath)return;
                 //...you code here
                 /* if you need form access
                 this.Invoke(new MethodInvoker(() =>{ textBox1.Text = "...";}));
                 */
                 Static.lastDomain = DateTime.Now;
                 Static.lastDomainStr = e.FullPath;
             }
             private void Second(object source, FileSystemEventArgs e)
             {
                  //...Second rised
             }
       }
    }

2019-03-11 11:14:37

FileSystemWatcher Changed事件被引发两次

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