Delphi中如何实时的监控一个目录(2)

时间：2011/9/3 15:19:53 点击：

procedure TForm1.Button2Click(Sender: TObject);
begin
{establish a notification for file name changes on the selected directory}
NotificationHandle := FindFirstChangeNotification(PChar(DirectoryListBox1.Directory), FALSE,FILE_NOTIFY_CHANGE_FILE_NAME);
{if the notification was set up correctly, modify some UI elements...}
if (NotificationHandle <> INVALID_HANDLE_VALUE) then
begin
Button1.Enabled := TRUE;
Button2.Enabled := FALSE;
end
else
begin
{...otherwise indicate that there was an error}
ShowMessage('There was an error setting the notification');
Exit;
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
dwResult: DWORD; // holds the result of waiting on the notification
Waiting: Boolean; // loop control variable
begin
{setup the loop control for a continuous loop}
Waiting := TRUE;
{indicate that the application is waiting for the change notification to fire}
Button1.Enabled := FALSE;
StatusBar1.SimpleText := 'Now waiting for a filename change';
Application.ProcessMessages;
{enter the loop}
while Waiting do
begin
{at this point, the application is suspended until the notification
object is signaled that a filename change has occured in the
selected directory (this includes file deletions)}
dwResult := WaitForSingleObject(NotificationHandle,INFINITE);
if (dwResult = WAIT_OBJECT_0) then

begin
{indicate that the notification object was signaled}
ShowMessage('The selected directory signaled a filename change');

{query the user to see if they wish to continue monitoring this
directory}
if Application.MessageBox('Do you wish to continue monitoring this directory?', 'Continue?', MB_ICONQUESTION or
MB_YESNO) = IDYES then

{if the user wishes to continue monitoring the directory, reset
the notification object and continue the loop...}
FindNextChangeNotification(NotificationHandle)
else
{...otherwise break out of the loop}
Waiting := FALSE;
end;
end;

{close the notification object}
FindCloseChangeNotification(NotificationHandle);

{reset UI elements}

Button1.Enabled := FALSE;
Button2.Enabled := TRUE;
StatusBar1.SimpleText := '';
FileListBox1.Update;
end;
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