In this article I will explain with an example, how to Zip a Folder (Directory) and download in ASP.Net using C# and VB.Net.
This article will explain how to Zip a Folder (Directory) containing multiple files into a single Zip Archive File and download using the DotNetZip Library in ASP.Net using C# and VB.Net.
 
 
Referencing the DotNetZip Library
You will need to download the DotNetZip Library DLL using the Download Link provided below.
Download DotNetZip Or your will find the DLL in the attached sample at the end of the article.
Once you have the DLL you need to place the Ionic.Zip.Reduced.dll in the BIN Folder.
 
 
Namespaces
You will need to import the following Namespaces.
C#
using System.IO;
using Ionic.Zip;
using System.Collections.Generic;
 
VB.Net
Imports System.IO
Imports Ionic.Zip
Imports System.Collections.Generic
 
 
Storage of Files on Server Directory
In my website I have created a Folder named Files which contains the following files as shown in the screenshot below.
Zip a Folder (Directory) and Download in ASP.Net using C# and VB.Net
 
 
Displaying the Files stored in Folder on the Server in ASP.Net GridView
I have placed an ASP.Net GridView control on my Web Page along with a Button that will be used to download the Files.
You will notice that I have placed a CheckBox Control in the GridView, this CheckBox will allow users to select the file that wish to download.
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" EmptyDataText="No files available">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:CheckBox ID="chkSelect" runat="server" />
                <asp:Label ID="lblFilePath" runat="server" Text='<%# Eval("Value") %>' Visible="false"></asp:Label>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="Text" HeaderText="File Name" />
    </Columns>
</asp:GridView>
<br />
<asp:Button ID="btnDownload" runat="server" Text="Download" OnClick="DownloadFiles" />
 
The following code is used to bind the List of Files from the Server Folder or Directory to the ASP.Net GridView control.
C#
protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        string[] filePaths = Directory.GetFiles(Server.MapPath("~/Files/"));
        List<ListItem> files = new List<ListItem>();
        foreach (string filePath in filePaths)
        {
            files.Add(new ListItem(Path.GetFileName(filePath), filePath));
        }
        GridView1.DataSource = files;
        GridView1.DataBind();
    }
}
 
VB.Net
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim filePaths As String() = Directory.GetFiles(Server.MapPath("~/Files/"))
        Dim files As New List(Of ListItem)()
        For Each filePath As String In filePaths
            files.Add(New ListItem(Path.GetFileName(filePath), filePath))
        Next
        GridView1.DataSource = files
        GridView1.DataBind()
    End If
End Sub
 
 
Zip a Folder (Directory) and Download in ASP.Net using C# and VB.Net
When the Download Button is clicked, first an object of the DotNetZip Library is created and a loop is executed over the GridView rows and the all the files for which the Checkbox is checked are added to the Zip object.
Finally the Zip object is downloaded as Zip file.
C#
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();
    }
}
 
VB.Net
Protected Sub DownloadFiles(sender As Object, e As EventArgs)
    Using zip As New ZipFile()
        zip.AlternateEncodingUsage = ZipOption.AsNecessary
        zip.AddDirectoryByName("Files")
        For Each row As GridViewRow In GridView1.Rows
            If TryCast(row.FindControl("chkSelect"), CheckBox).Checked Then
                Dim filePath As String = TryCast(row.FindControl("lblFilePath"), Label).Text
                zip.AddFile(filePath, "Files")
            End If
        Next
        Response.Clear()
        Response.BufferOutput = False
        Dim zipName As String = [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()
    End Using
End Sub
 
 
Screenshot
Zip a Folder (Directory) and Download in ASP.Net using C# and VB.Net
 
 
Demo
 
 
Downloads