FileSystemWatcher：将多个过滤事件聚合成一个？

Question

拿下面的代码来说，watcher引发的事件都调用同一个方法：

[NonSerialized]
private FileSystemWatcher Watcher;

private void WatcherInit()
{
    Watcher ??= new FileSystemWatcher();

    Watcher.Path                  = Application.dataPath;
    Watcher.Filter                = "*.mat";
    Watcher.IncludeSubdirectories = true;
    Watcher.NotifyFilter          = NotifyFilters.LastWrite | NotifyFilters.DirectoryName | NotifyFilters.FileName | NotifyFilters.CreationTime;

    Watcher.EnableRaisingEvents = true;

    Watcher.Changed += OnWatcherChanged;
    Watcher.Created += OnWatcherCreated;
    Watcher.Deleted += OnWatcherDeleted;
    Watcher.Renamed += OnWatcherRenamed;
}

private void OnWatcherRenamed(object sender, RenamedEventArgs args)
{
    DoViewReload();
}

private void OnWatcherDeleted(object sender, FileSystemEventArgs args)
{
    DoViewReload();
}

private void OnWatcherCreated(object sender, FileSystemEventArgs args)
{
    DoViewReload();
}

private void OnWatcherChanged(object sender, FileSystemEventArgs args)
{
    DoViewReload();
}

这导致同一方法被多次调用，而我希望它只被调用一次。

在我的例子中，我刷新了 UI，当我创建一个新文件时它发生了 3 次。

我想应该有一些计时器可以等待连续的事件并连接它们，然后只发出一个调用；这只是一个猜测，也许还有我不知道的更好的解决方案。

有什么想法吗？

Answer 1

以下模式最终运行良好：

private void OnWatcherRenamed(object sender, RenamedEventArgs args)
{
    WatcherTimerRestart();
}

private void OnWatcherDeleted(object sender, FileSystemEventArgs args)
{
    WatcherTimerRestart();
}

private void OnWatcherCreated(object sender, FileSystemEventArgs args)
{
    WatcherTimerRestart();
}

private void OnWatcherChanged(object sender, FileSystemEventArgs args)
{
    WatcherTimerRestart();
}

private void WatcherTimerRestart()
{
    WatcherTimer.Enabled = false;
    WatcherTimer.Enabled = true;
}

private void WatcherTimerCallback(object sender, ElapsedEventArgs e)
{
    // do the funky stuff you wanted to execute only once
}

备注：

我决定将 UI 切换到特定状态，例如：

Waiting for I/O to complete...

并且在这种情况下，将间隔设置为不太低的值（例如 3000 毫秒）会更好：

用户有时间阅读消息
实践证明较低的值是不够的，即使是小文件 and/or SSD
FileSystemWatcher 引发事件的速度很慢

下面是关于根据用户操作引发的事件的迷你table：

User action	Callbacks raised
Create	Created
Delete	Changed, Deleted
Rename	Changed, Created, Deleted
Move	Changed, Created, Deleted

您可能需要注意，具有讽刺意味的是，即使对于重命名操作，也根本不会引发 Renamed；这可能与应用程序如何重命名文件有关，有多种方法可以做到这一点。

FileSystemWatcher：将多个过滤事件聚合成一个？

FileSystemWatcher: aggregate multiple filter events into a single one?

c#

design-patterns

filesystemwatcher