How to Download Multiple Files using the Response Class

Question

I have a classic ASP.Net app that downloads a file using the Response class:

            Response.Clear();
            Response.ClearHeaders();
            Response.ClearContent();
            Response.AddHeader("Content-Disposition", "attachment; filename=" + Path.GetFileName(txt_inputfile.Text));
            Response.AddHeader("Content-Length", txt_inputfile.Text.Length.ToString());
            Response.ContentType = "text/plain";
            Response.TransmitFile(txt_inputfile.Text);
            Response.Flush();
            Response.End();

Can this class be used when I want to download multiple files in one event? I use a 4.8 .Net framework.

Answer 1

Hi @Coreysan,

Each file download is a response.

Each request can only have one response (apart from push notifications of course!)

Instead, render a page which either contains links, or makes seperate requests to download each file.

Or, download a zip archive containing multiple files.

You can try compressing multiple files into a single Zip Archive file using the DotNetZip library in ASP.Net.

Demo

protected void DownloadFiles(object sender, EventArgs e)
{
    using (ZipFile zip = new ZipFile())
    {
        zip.AlternateEncodingUsage = ZipOption.AsNecessary;
        zip.AddDirectoryByName("Files");
        foreach (GridViewRow row in GridView1.Rows)
        {
            if ((row.FindControl("chkSelect") as CheckBox).Checked)
            {
                string filePath = (row.FindControl("lblFilePath") as Label).Text;
                zip.AddFile(filePath, "Files");
            }
        }
        Response.Clear();
        Response.BufferOutput = false;
        string zipName = String.Format("Zip_{0}.zip", DateTime.Now.ToString("yyyy-MMM-dd-HHmmss"));
        Response.ContentType = "application/zip";
        Response.AddHeader("content-disposition", "attachment; filename=" + zipName); 
        zip.Save(Response.OutputStream);
        Response.End();
    }
}

Best regards,
Lan Huang

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Answer 2

Can this class be used when I want to download multiple files in one event?

No. The browser can download one file at a time. For multiple files zip the files in into one zipped file and download the zipped file.