codice:
Dim path As String = Server.MapPath("~")
Dim InformazioniSuDirectory As New DirectoryInfo(path)
Dim ListaDirectories As DirectoryInfo() = InformazioniSuDirectory.GetDirectories()  'senza *.*
For Each XDIR As DirectoryInfo In ListaDirectories
      ' tuo codice per creare ddl
      Dim listaFile as FileInfo() = XDIR.GetFiles() 'senza *.* prende tutti i file
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