c# - FileSystemWatcher 不会在一段时间后触发

Question

我有以下代码用于监视文本文件的目录，该目录每天两次获取新文件，该代码在一段时间内工作正常但之后它停止触发 OnCreated 事件...

[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public static void Run()
{
    FileSystemWatcher watcher = new FileSystemWatcher();
    watcher.Path = @"c:\users\documents\";

    watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite
       | NotifyFilters.FileName | NotifyFilters.DirectoryName;

    watcher.Filter = "*.txt";

    // Add event handlers.
    watcher.Created += new FileSystemEventHandler(OnCreated);

    // Begin watching.
    watcher.EnableRaisingEvents = true;

    // Wait for the user to quit the program.
    Console.WriteLine("Press \'q\' to quit the sample.");
    while(Console.Read()!='q');
}

private static void OnCreated(object source, FileSystemEventArgs e)
{
   Console.WriteLine("File: " +  e.FullPath + " " + e.ChangeType);
}

无法找出问题。

另外，我想知道一个万无一失的替代方案(如果有的话)，因为我觉得这个不可靠..

Answer 1

因为 Run 方法完成后，watcher 有资格进行垃圾回收。这意味着一段时间后 watcher 将被收集并且显然将停止引发事件。

要解决，请在外部范围内保留观察者的引用:

private static FileSystemWatcher watcher;

public static void Run()
{
    watcher = new FileSystemWatcher();
    ...
}