Check excel file is open by other user - vb.net

Question

I have a excel file place on server.
I am using a application which written by VB.NET to open file in read only mode.
User 1 open file in read only mode.
How can user 2 detect that file is open or not status?
Thanks,
An

Answer 1

You need to test the file Read Only as ReadWrite will fail if the file is ReadOnly status.
Below are some methods. Not sure where I got them all from except the last one by Randy Birch.
Speed tests favour FileIsOpen3 and FileIsOpen4.
Function FileIsOpen1(ByVal pathfile As String) As Boolean
Dim ff As Integer
If System.IO.File.Exists(pathfile) Then
Try
ff = FreeFile()
Microsoft.VisualBasic.FileOpen(ff, pathfile, OpenMode.Binary, OpenAccess.Read, OpenShare.LockReadWrite)
Return False
Catch
Return True
Finally
FileClose(ff)
End Try
Return True
End If
End Function
Function FileIsOpen2(ByVal pathfile As String) As Boolean
Dim stream As FileStream = Nothing
Dim fi As FileInfo = Nothing
If System.IO.File.Exists(pathfile) Then
Try
fi = New System.IO.FileInfo(pathfile)
stream = fi.Open(FileMode.Open, FileAccess.Read, FileShare.None)
Return True
Catch generatedExceptionName As IOException
Return False
Finally
If stream IsNot Nothing Then
stream.Close()
End If
fi = Nothing
End Try
Return True
End If
End Function
Private Function FileIsOpen3(ByVal pathfile As String) As Boolean
Try
Dim fs As IO.FileStream = IO.File.Open(pathfile, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.None)
fs.Close()
fs.Dispose()
fs = Nothing
Return False
Catch ex As IO.IOException ' File open
Return True
Catch ex As Exception ' Unknown error
Return True
End Try
End Function
Private Declare Function CreateFile Lib "kernel32" _
Alias "CreateFileA" _
(ByVal lpFileName As String, _
ByVal dwDesiredAccess As Long, _
ByVal dwShareMode As Long, _
ByVal lpSecurityAttributes As Long, _
ByVal dwCreationDisposition As Long, _
ByVal dwFlagsAndAttributes As Long, _
ByVal hTemplateFile As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" _
(ByVal hFile As Long) As Long
' Method
Shared Function FileIsOpen4(ByVal pathfile As String) As Boolean
' Is File In Use ©1996-2009 Randy Birch
' http://vbnet.mvps.org/index.html?code/fileapi/createfile_inuse.htm
Const GENERIC_READ As Long = &H80000000
Const INVALID_HANDLE_VALUE As Long = -1
Const OPEN_EXISTING As Long = 3
Const FILE_ATTRIBUTE_NORMAL As Long = &H80
Dim hFile As Long
If System.IO.File.Exists(pathfile) Then
Try
' note that FILE_ATTRIBUTE_NORMAL (&H80) has a different value than VB's constant vbNormal (0)!
hFile = CreateFile(pathfile, GENERIC_READ, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0&)
' this will evaluate to either -1 (File in use) or 0 (File free)
Return hFile = INVALID_HANDLE_VALUE
Catch ex As Exception
MessageBox.Show(ex.ToString)
Finally
CloseHandle(hFile)
End Try
Else
Return True
End If
End Function

Answer 2

The second user can try to open the file in read-write mode to know if the file is being used.