为什么在 Windows 7 而不是 Windows 8 上检测到 FileSystemWatcher 属性更改?

Why are FileSystemWatcher Attribute changes detected on Windows 7 but not Windows 8?(为什么在 Windows 7 而不是 Windows 8 上检测到 FileSystemWatcher 属性更改?)

问题描述

我有一些代码使用 FileSystemWatcher 来监视我的应用程序之外的文件更改.

I have some code that uses FileSystemWatcher to monitor file changes outside of my application.

在 Windows 7 上，使用 .NET 4，当我的应用程序运行时，以下代码将检测文件何时被编辑并保存在记事本等应用程序中.但是，此逻辑在 Windows 8 上使用 .NET 4 时不起作用.具体而言，FileSystemWatcher 的 Changed 事件永远不会触发.

On Windows 7, using .NET 4, the below code would detect when a file had been edited and saved in an application like Notepad, while my app was running. However, this logic isn't working using .NET 4 on Windows 8. Specifically, the FileSystemWatcher's Changed event never fires.

public static void Main(string[] args)
{
    const string FilePath = @"C:userscraigdesktop
otes.txt";

    if (File.Exists(FilePath))
    {
        Console.WriteLine("Test file exists.");
    }

    var fsw = new FileSystemWatcher();
    fsw.NotifyFilter = NotifyFilters.Attributes;
    fsw.Path = Path.GetDirectoryName(FilePath);
    fsw.Filter = Path.GetFileName(FilePath);

    fsw.Changed += OnFileChanged;
    fsw.EnableRaisingEvents = true;

    // Block exiting.
    Console.ReadLine();
}

private static void OnFileChanged(object sender, FileSystemEventArgs e)
{
    if (File.Exists(e.FullPath))
    {
        Console.WriteLine("File change reported!");
    }
}

我知道我可以将 NotifyFilter 更改为也包含 NotifyFilters.LastWrite，这可以解决我的问题.但是，我想了解为什么此代码在 Windows 7 上有效，但现在无法在 Windows 8 上触发 Changed 事件.我也很想知道在 Windows 8 中运行时是否有办法恢复我的 Windows 7 FileSystemWatcher 行为(不更改 NotifyFilter).

I understand that I can alter the NotifyFilter to also include NotifyFilters.LastWrite, which can solve my problem. However, I want to understand why this code worked on Windows 7 but now fails to fire the Changed event on Windows 8. I'm also curious to know if there's a way to restore my Windows 7 FileSystemWatcher behavior when running in Windows 8 (without changing the NotifyFilter).

推荐答案

到处都是评论太多，我只是添加一个答案来验证您是否意识到以下问题:

There are too many comments everywhere, I will just add an answer to verify that you are aware of the following issues:

• 获取文件系统观察器事件在 main 上发生UI 线程(寻找 Hans Passant 的答案)
• WPF - 无法更改 OnChanged 方法中的 GUI 属性(从 FileSystemWatcher 触发)

• get filesystemwatcher events to occur on main UI thread (look for Hans Passant's answer)
• WPF - Cannot change a GUI property inside the OnChanged method (fired from FileSystemWatcher)

显然问题在于该事件是在后台线程上引发的，您需要将调用编组回 UI 线程.

我在使用 FileSystemWatcher 类时遇到了很多麻烦，因此决定不使用它，正如您在此处所描述的那样:https://stackoverflow.com/a/22768610/129130.但是，我遇到的问题可能是由于线程同步问题和/或硬件问题造成的.

I have experienced a lot of trouble with the FileSystemWatcher class, and decided not to use it as you can see me describe here: https://stackoverflow.com/a/22768610/129130 . It is possible, however, that the problems I experienced were due to thread synchronization issues and / or hardware issues.

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