Drew Wutka
DWUTKA at Marlow.com
Mon Sep 21 17:01:22 CDT 2009
Sorry, no idea how to do this in C#, never dug into that language. But
in VB, I have a class that does this. It doesn't use a timer to do a
Dir(), it uses the waitforsingleobject to loop with a hook into the OS
file system.
It's very cool, though I've never really put it into use for anything.
It's a Class (in VB (6)), which raises an event for any file change.
What's WAY better then the Dir method, is that the hook is applicable to
all sub folders. (So if you monitor C:\), you will see EVERY SINGLE
file activity (create, read, change, modify and rename).
Here's the class in VB(6):
FSMoniter:
Option Explicit
Event FileActivity(strFileName As String, Action As FS_File_Actions)
Public PathToMonitor As String
Dim blKeepMonitoring As Boolean
Private Declare Function FS_CreateFile Lib "kernel32" Alias
"CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As
Long, ByVal dwShareMode As Long, lpSecurityAttributes As Any, ByVal
dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal
hTemplateFile As Long) As Long
Private Declare Function FS_ReadDirChanges Lib "kernel32" Alias
"ReadDirectoryChangesW" (ByVal hDir As Long, ByVal lpBuffer As Long,
ByVal lenBuffer As Long, ByVal bWatchSubtree As Boolean, ByVal
dwNotifyFilter As Long, ByRef dwBytesReturned As Long, ByVal
lpOverLapped As Long, ByVal dwCallBack As Long) As Long
Private Declare Function FS_CloseHandle Lib "kernel32" Alias
"CloseHandle" (ByVal hObject As Long) As Long
Private Declare Function FS_CreateEvent Lib "kernel32" Alias
"CreateEventA" (lpEventAttributes As Any, ByVal bManualReset As Long,
ByVal bInitialState As Long, ByVal lpName As String) As Long
Private Declare Function FS_ResetEvent Lib "kernel32" Alias "ResetEvent"
(ByVal hEvent As Long) As Long
Private Declare Sub FS_CopyMemory Lib "kernel32" Alias "RtlMoveMemory"
(ByVal Destination As Long, ByVal Source As Long, ByVal Length As Long)
Private Declare Function FS_WaitForSingleObject Lib "kernel32" Alias
"WaitForSingleObject" (ByVal hHandle As Long, ByVal dwMilliseconds As
Long) As Long
Private Const FILE_LIST_DIRECTORY = (&H1)
Private Const FILE_SHARE_DELETE = &H4
Private Const FILE_SHARE_READ = &H1
Private Const FILE_SHARE_WRITE = &H2
Private Const OPEN_EXISTING = 3
Private Const FILE_FLAG_BACKUP_SEMANTICS = &H2000000
Private Const FILE_FLAG_OVERLAPPED = &H40000000
Private Const FILE_NOTIFY_CHANGE_ATTRIBUTES = &H4
Private Const FILE_NOTIFY_CHANGE_CREATION = &H40
Private Const FILE_NOTIFY_CHANGE_DIR_NAME = &H2
Private Const FILE_NOTIFY_CHANGE_FILE_NAME = &H1
Private Const FILE_NOTIFY_CHANGE_LAST_ACCESS = &H20
Private Const FILE_NOTIFY_CHANGE_LAST_WRITE = &H10
Private Const FILE_NOTIFY_CHANGE_SECURITY = &H100
Private Const FILE_NOTIFY_CHANGE_SIZE = &H8
Private Const WAIT_TIMEOUT = 258&
Public Enum FS_File_Actions
FILE_ACTION_ADDED = &H1
FILE_ACTION_MODIFIED = &H3
FILE_ACTION_REMOVED = &H2
FILE_ACTION_RENAMED_NEW_NAME = &H5
FILE_ACTION_RENAMED_OLD_NAME = &H4
End Enum
Private Type FS_FILE_NOTIFY_INFORMATION
NextEntryOffset As Long
Action As FS_File_Actions
FileNameLength As Long
FileName(1024 - 1) As Byte
End Type
Private Type FS_OVERLAPPED
Internal As Long
InternalHigh As Long
Offset As Long
OffsetHigh As Long
hEvent As Long
End Type
Public Function StartMonitoring()
'On Error GoTo ErrorHandler
Dim hDir As Long
Dim dwReturn As Long
Dim intReturnSize As Long
Dim ovr As FS_OVERLAPPED
Dim hEvent As Long
Dim intWatchFilter As Long
Dim fni As FS_FILE_NOTIFY_INFORMATION
Dim fniBuf(0 To 1024 * 5 - 1) As Byte
Dim BufferPos As Long
Dim strFileName As String
blKeepMonitoring = True
intWatchFilter = FILE_NOTIFY_CHANGE_ATTRIBUTES +
FILE_NOTIFY_CHANGE_CREATION + FILE_NOTIFY_CHANGE_DIR_NAME +
FILE_NOTIFY_CHANGE_FILE_NAME + FILE_NOTIFY_CHANGE_LAST_ACCESS +
FILE_NOTIFY_CHANGE_LAST_WRITE + FILE_NOTIFY_CHANGE_SECURITY +
FILE_NOTIFY_CHANGE_SIZE
hDir = FS_CreateFile(PathToMonitor, FILE_LIST_DIRECTORY, FILE_SHARE_READ
Or FILE_SHARE_DELETE Or FILE_SHARE_WRITE, Null, OPEN_EXISTING,
FILE_FLAG_BACKUP_SEMANTICS Or FILE_FLAG_OVERLAPPED, 0)
If hDir = -1 Then
MsgBox "Invalid Handle Value...Error: " & Err.LastDllError
End If
hEvent = FS_CreateEvent(0&, True, True, "FS_IOEvent")
ovr.hEvent = hEvent
dwReturn = FS_ReadDirChanges(hDir, VarPtr(fniBuf(0)), UBound(fniBuf) +
1, True, intWatchFilter, intReturnSize, VarPtr(ovr), 0&)
If dwReturn = 0 Then
MsgBox "Error Calling ReadDirChanges"
MsgBox Err.LastDllError
MsgBox ovr.hEvent
MsgBox hDir
End If
Do Until blKeepMonitoring = False
BufferPos = 0
dwReturn = FS_WaitForSingleObject(hEvent, 100)
If dwReturn <> WAIT_TIMEOUT Then
'MsgBox fniBuf(0)
FS_CopyMemory VarPtr(fni), VarPtr(fniBuf(BufferPos)), Len(fni)
strFileName = fni.FileName
strFileName = Left(strFileName, fni.FileNameLength / 2)
RaiseEvent FileActivity(strFileName, fni.Action)
While fni.NextEntryOffset <> 0
BufferPos = BufferPos + fni.NextEntryOffset
FS_CopyMemory VarPtr(fni), VarPtr(fniBuf(BufferPos)),
Len(fni)
strFileName = fni.FileName
strFileName = Left(strFileName, fni.FileNameLength / 2)
RaiseEvent FileActivity(strFileName, fni.Action)
Wend
FS_ResetEvent hEvent
dwReturn = FS_ReadDirChanges(hDir, VarPtr(fniBuf(0)),
UBound(fniBuf) + 1, True, intWatchFilter, intReturnSize, VarPtr(ovr),
0&)
End If
DoEvents
Loop
ErrorHandler:
FS_CloseHandle hEvent
FS_CloseHandle hDir
End Function
Public Function StopMonitoring()
blKeepMonitoring = False
End Function
Private Sub Class_Initialize()
blKeepMonitoring = False
End Sub
Then to use this class, this is the code behind a sample form with a
listbox, text box, and two command buttons:
Option Explicit
Dim WithEvents fsm As FSMonitor
Private Sub Command1_Click()
Set fsm = New FSMonitor
fsm.PathToMonitor = Me.txtPath
fsm.StartMonitoring
End Sub
Private Sub Command2_Click()
fsm.StopMonitoring
End Sub
Private Sub fsm_FileActivity(strFileName As String, Action As
FS_File_Actions)
Select Case Action
Case FILE_ACTION_ADDED
Me.lstFileActivity.AddItem strFileName & " - Added"
Case FILE_ACTION_MODIFIED
Me.lstFileActivity.AddItem strFileName & " - Modified"
Case FILE_ACTION_REMOVED
Me.lstFileActivity.AddItem strFileName & " - Removed"
Case FILE_ACTION_RENAMED_NEW_NAME
Me.lstFileActivity.AddItem strFileName & " - New Name"
Case FILE_ACTION_RENAMED_OLD_NAME
Me.lstFileActivity.AddItem strFileName & " - Old Name"
End Select
End Sub
Run this, and use the path of C:\ and watch all the standard file
activity happening with just plain old windows! LOL
Drew
-----Original Message-----
From: dba-vb-bounces at databaseadvisors.com
[mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Saturday, September 19, 2009 1:44 PM
To: VBA
Subject: [dba-VB] c# - Monitor folder and run application
Just wondering if anyone has already done this and could send me a
solution.
I need to monitor a folder and run an application if a file exists.
I have found code that runs an app and waits a time period for it to
complete, closing the app if it
doesn't complete within that time period.
In addition to that I need the monitoring code, and all wrapped up in a
single solution.
This doesn't appear too tough given all the code snipits out there but
why reinvent the wheel if you
have done it.
--
John W. Colby
www.ColbyConsulting.com
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