VB.Net FileSystemWatcher-多个文件夹和多个文件

Question

I have a requirement of monitoring a root folder under which there are multiple folders and each folder containing multiple files (.csv) These files are being copied to a workstation from a server using some other third party tool. I have to monitor the workstation root's folder and as an when a .csv file is created or updated in any of the child folders, I have to write the .csv file data (updated or new) to a sql server database. While writing the data to the sql server, I need to capture the child folder name in which the .csv file was updated/created. This way I can have separate folder's data in one database file.

While running the program on the workstation pc, the application crashes without any specific error message. And since the app is run on a remote pc, I cannot debug the app to check which line is causing the crash. Below is the code:

Public Class FolderWatchAndProcess
Dim blnMonitorUpdated As Boolean = True
Dim blnMonitorCreated As Boolean = True
Dim blnShowMessage As Boolean
Dim strFullFileName As String
Dim strFileName As String
Dim strFolderName As String
Private Delegate Sub updateLabel(ByVal newLabel As String)

Private Sub updateLabelHandler(ByVal labelText As String)
    lblMetNo.Text = labelText
End Sub

Private Sub ReadAndInsertCSVData()
' This routine checks for duplicates and inserts new records into the sql server database
End Sub

Private Sub Form_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    'lblMonitorPath.Text = "C:\RootFolder\"
    'btnStartWatching_Click(Nothing, Nothing)
    'Me.WindowState = FormWindowState.Minimized
End Sub

Private Sub btnStartWatching_Click(sender As Object, e As EventArgs) Handles btnStartWatching.Click
    btnStartWatching.Text = "Stop Watching"
    Dim aFileWatcherInstance As ArrayList = New ArrayList
    For Each sMonitorFolder As String In lstFolders.Items
        If IO.Directory.Exists(sMonitorFolder) Then
            Dim oFileWatcher As FileSystemWatcher = New FileSystemWatcher
            oFileWatcher.Path = sMonitorFolder
            oFileWatcher.Filter = "*.CSV"
            If blnMonitorUpdated Then
                AddHandler oFileWatcher.Changed, AddressOf Me.FileSystemWatcherUpdated
            Else
                'RemoveHandler , AddressOf Me.FileSystemWatcherUpdated
            End If
            If blnMonitorCreated Then
                AddHandler oFileWatcher.Created, AddressOf Me.FileSystemWatcherCreated
            Else
                'RemoveHandler , AddressOf Me.FileSystemWatcherCreated
            End If
            oFileWatcher.EnableRaisingEvents = True
            aFileWatcherInstance.Add(oFileWatcher)
        End If
    Next
End Sub

Private Sub FileSystemWatcherCreated(ByVal sender As Object, ByVal e As System.IO.FileSystemEventArgs)
    strFullFileName = e.FullPath
    strFileName = Mid(e.Name, 3, Len(e.Name))
    strFolderName = strFileName.Split("_")(0)
    If Me.InvokeRequired Then
        Dim d As New updateLabel(AddressOf updateLabelHandler)
        Me.BeginInvoke(d, New Object() {strFolderName})
    Else
        updateLabelHandler(strFolderName)
    End If
    ReadAndInsertCSVData()
End Sub

Private Sub FileSystemWatcherDeleted(ByVal sender As Object, ByVal e As System.IO.FileSystemEventArgs)
    'A file has been deleted from the child directory.
End Sub

Private Sub FileSystemWatcherUpdated(ByVal sender As Object, ByVal e As System.IO.FileSystemEventArgs)
    strFullFileName = e.FullPath
    strFileName = Mid(e.Name, 3, Len(e.Name))
    strFolderName = strFileName.Split("_")(0)
    If Me.InvokeRequired Then
        Dim d As New updateLabel(AddressOf updateLabelHandler)
        Me.BeginInvoke(d, New Object() {strFolderName})
    Else
        updateLabelHandler(strFolderName)
    End If
    ReadAndInsertCSVData()
End Sub

End Class

Any help would be appreciated.

Answer 1

the Changed event will fire multiple times:

https://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher.changed(v=vs.110).aspx

probably you can use the IsFileLocked function that mention at here:

I keep getting exception sometimes on System.Threading.Tasks.TaskCompletionSource<bool> how can i solve it?