Downloading any file to the browser – Part II: using ASP.NET

call-download

<a href="download.aspx?file=/images/logo.gif">Download the logo image</a>

download.aspx

<%@ Page language="vb" runat="server" explicit="true" strict="true" %>
<script language="vb" runat="server">
Sub Page_Load(Sender As Object, E As EventArgs)
   Dim strRequest As String = Request.QueryString("file") '-- if something was passed to the file querystring
   If strRequest <> "" Then 'get absolute path of the file
      Dim path As String = Server.MapPath(strRequest) 'get file object as FileInfo
      Dim file As System.IO.FileInfo = New System.IO.FileInfo(path) '-- if the file exists on the server
      If file.Exists Then 'set appropriate headers
         Response.Clear()
         Response.AddHeader("Content-Disposition", "attachment; filename=" & file.Name)
         Response.AddHeader("Content-Length", file.Length.ToString())
         Response.ContentType = "application/octet-stream"
         Response.WriteFile(file.FullName)
         Response.End 'if file does not exist
      Else
         Response.Write("This file does not exist.")
      End If 'nothing in the URL as HTTP GET
   Else
      Response.Write("Please provide a file to download.")
   End If
End Sub
</script>

https://evagoras.com/2011/02/08/downloading-any-file-to-the-browser-part-ii-using-asp-net/