vb.net - 文件系统观察器不工作

Question

我在 Form1_Load 中添加了 FileSystemWatcher，如下所示:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ....................
        Dim watcher As New FileSystemWatcher()
        'For watching current directory
        watcher.Path = "/"
        'For watching status.txt for any changes
        watcher.Filter = "status.txt"
        watcher.NotifyFilter = NotifyFilters.LastWrite
        watcher.EnableRaisingEvents = True
        AddHandler watcher.Changed, AddressOf OnChanged
End Sub

我有一个 OnChanged 函数，它是一个简单的 MessageBox。不过，当我更改 status.txt 文件时，没有显示消息框。

Answer 1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim watcher As New IO.FileSystemWatcher()

'For watching current directory
watcher.Path = **System.IO.Directory.GetCurrentDirectory()** 'Note how to obtain current directory
watcher.NotifyFilter = NotifyFilters.LastWrite

'When I pasted your code and created my own status.txt file using 
'right click->new->Text File on Windows 7 it appended a '.txt' automatically so the
'filter wasn't finding it as the file name was status.txt.txt renaming the file
'solved the problem
watcher.Filter = "status.txt" 

AddHandler watcher.Changed, AddressOf OnChanged

watcher.EnableRaisingEvents = True
End Sub

Private Shared Sub OnChanged(ByVal source As Object, ByVal e As IO.FileSystemEventArgs)
MessageBox.Show("Got it")
End Sub

来自http://bartdesmet.net/blogs/bart/archive/2004/10/21/447.aspx

您可能会注意到，在某些情况下，单个创建事件会生成多个由您的组件处理的 Created 事件。例如，如果您使用 FileSystemWatcher 组件监视目录中新文件的创建，然后使用记事本创建文件进行测试，则即使只创建了一个文件，您也可能会看到生成了两个 Created 事件。这是因为记事本在写入过程中执行多个文件系统操作。记事本批量写入磁盘，创建文件内容，然后创建文件属性。其他应用程序可以以相同的方式执行。由于 FileSystemWatcher 监视操作系统事件，因此将拾取这些应用程序触发的所有事件