# DotNetZip - ASP.NET VB Example

## ASP.NET Example in VB

Here's an Example ASP.NET page, using VB, that dynamically creates a zip file and saves it to Response.OutStream. From the browser, the user will be prompted with the familiar download dialog box, allowing Open, Save, or Cancel of the generated zip file.

    <%@ Page
        Language="VB"
        Debug="true"
    %>

    <%@ Import Namespace="System.Text" %>
    <%@ Import Namespace="System.IO" %>
    <%@ Import Namespace="Ionic.Zip" %>
    <%@ Import Namespace="System.Collections.Generic" %>

    <script language="VB" runat="server">

    ' ZipExample.aspx
    '
    ' This .aspx page demonstrates how to use the DotNetZip library from within ASP.NET.
    '
    ' To run it,
    '  1. drop the Ionic.Zip.dll into the \bin directory of your asp.net app
    '  2. create a subdirectory called "fodder" in your web app directory.
    '  3. copy into that directory a variety of random files.
    '  4. insure your web.config is properly set up (See below)
    '
    '
    ' notes:
    '  This requies the .NET Framework 3.5 - because it uses the ListView control that is
    '  new for ASP.NET in the .NET Framework v3.5.
    '
    '  To use this control, you must add the new web controls.  Also, you must use the v3.5 compiler.
    '  Here's an example web.config that works with this aspx file:
    '
    '    <configuration>
    '      <system.web>
    '        <trust level="Medium" />
    '        <compilation defaultLanguage="c#" />
    '        <pages>
    '          <controls>
    '            <add tagPrefix="asp" namespace="System.Web.UI.WebControls"
    '                 assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    '          </controls>
    '        </pages>
    '      </system.web>
    '      <system.codedom>
    '        <compilers>
    '          <compiler language="c#;cs;csharp"
    '                extension=".cs"
    '                warningLevel="4"
    '                type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
    '            <providerOption name="CompilerVersion" value="v3.5" />
    '            <providerOption name="WarnAsError" value="false" />
    '          </compiler>
    '
    '          <compiler language="vb;vbs;visualbasic;vbscript"
    '                    extension=".vb"
    '                    warningLevel="4"
    '                    type="Microsoft.VisualBasic.VBCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
    '            <providerOption name="CompilerVersion" value="v3.5" />
    '            <providerOption name="OptionInfer" value="false" />
    '            <providerOption name="WarnAsError" value="false" />
    '          </compiler>
    '
    '      </system.codedom>
    '    </configuration>
    '
    '

    Dim width as String = "100%"

    Public Sub Page_Load (ByVal sender As Object, ByVal e As System.EventArgs)
        Try
            If Not ( Page.IsPostBack ) Then
                ' populate the dropdownlist
                ' must have a directory called "fodder" in the web app
                Dim homeDir as String = Server.MapPath(".")
                Dim sMappedPath as  String= Server.MapPath("fodder")

                Dim fqFilenames As New List(Of String)(System.IO.Directory.GetFiles(sMappedPath))

                Dim filenames as List(Of String) = _
                    fqFilenames.ConvertAll (Function(s) s.Replace(sMappedPath & "\", ""))

                ErrorMessage.InnerHtml = ""

                FileListView.DataSource = filenames
                FileListView.DataBind()
            End If

        Catch
            ' Ignored
        End Try

    End Sub

    Public Sub btnGo_Click (ByVal sender As System.Object, ByVal e As System.EventArgs)

        ErrorMessage.InnerHtml =""   ' debugging only
        Dim filesToInclude as New System.Collections.Generic.List(Of String)()
        Dim sMappedPath as String= Server.MapPath("fodder")
        Dim source As DataKeyArray= FileListView.DataKeys

        For Each item As ListViewDataItem in FileListView.Items

            Dim chkbox As CheckBox= CType(item.FindControl("include"), CheckBox)
            Dim lbl As Label = CType(item.FindControl("label"), Label)

            If Not (chkbox Is Nothing  OR  lbl Is Nothing) Then
                If (chkbox.Checked) Then
                    ErrorMessage.InnerHtml = ErrorMessage.InnerHtml & _
                            String.Format("adding file: {0}<br/>\n", lbl.Text)
                    filesToInclude.Add(System.IO.Path.Combine(sMappedPath,lbl.Text))
                End If
            End If
        Next

        If (filesToInclude.Count=0) Then
            ErrorMessage.InnerHtml = ErrorMessage.InnerHtml & "You did not select any files?<br/>\n"
        Else
            Response.Clear
            Response.BufferOutput= false

            Dim enc as Ionic.Zip.EncryptionAlgorithm = Ionic.Zip.EncryptionAlgorithm.None
            If (chkUseAes.Checked) Then
                enc = EncryptionAlgorithm.WinZipAes256
            End If

            Dim c As System.Web.HttpContext = System.Web.HttpContext.Current
            Dim ReadmeText As String= String.Format("README.TXT\n\nHello!\n\n" & _
                                             "This is a zip file that was dynamically generated at {0}\n" & _
                                             "by an ASP.NET Page running on the machine named '{1}'.\n" & _
                                             "The server type is: {2}\n" & _
                                             "The password used: {3}\n", _
                                             "Encryption: {4}\n", _
                                             System.DateTime.Now.ToString("G"), _
                                             System.Environment.MachineName, _
                                             c.Request.ServerVariables("SERVER_SOFTWARE"), _
                                             tbPassword.Text, _
                                             enc.ToString )
            Dim archiveName as String= String.Format("archive-{0}.zip", DateTime.Now.ToString("yyyy-MMM-dd-HHmmss"))
            Response.ContentType = "application/zip"
            Response.AddHeader("content-disposition", "filename=" + archiveName)

            Using zip as new ZipFile()
                ' the Readme.txt file will not be password-protected.
                zip.AddEntry("Readme.txt", ReadmeText, Encoding.Default)
                If Not String.IsNullOrEmpty(tbPassword.Text) Then
                    zip.Password = tbPassword.Text
                    zip.Encryption = enc
                End If

                ' filesToInclude is a string[] or List<String>
                zip.AddFiles(filesToInclude, "files")

                zip.Save(Response.OutputStream)
            End Using
            Response.Close

        End If

    End Sub

    </script>

    <html>
      <head>
        <link rel="stylesheet" href="style/basic.css">
      </head>

      <body>

        <form id="Form" runat="server">

          <h3> <span id="Title" runat="server" />Zip Files from ASP.NET </h3>

          <p>This page uses the .NET Zip library (see <a
          href="http://DotNetZip.codeplex.com">http://DotNetZip.codeplex.com/</a>)
          to dynamically create a zip archive, and then download it to the
          browser through Response.OutputStream.  This page is implemented
          in VB.NET.</p>

          <span class="SampleTitle"><b>Check the boxes to select the files, set a password if you like,
          then click the button to zip them up.</b></span>
          <br/>
          <br/>
          Password: <asp:TextBox id="tbPassword" Password='true' Text="" AutoPostBack runat="server"/>
          <span style="color:Red">(Optional)</span>
          <br/>
          <br/>
          Use AES?: <asp:CheckBox id="chkUseAes" AutoPostBack runat="server"/>
          <br/>
          <br/>
          <asp:Button id="btnGo" Text="Zip checked files" AutoPostBack OnClick="btnGo_Click" runat="server"/>

          <br/>
          <br/>
          <span style="color:red" id="ErrorMessage" runat="server"/>
          <br/>

          <asp:ListView ID="FileListView" runat="server">

            <LayoutTemplate>
              <table>
                <tr ID="itemPlaceholder" runat="server" />
              </table>
            </LayoutTemplate>

            <ItemTemplate>
              <tr>
                <td><asp:Checkbox ID="include" runat="server"/></td>
                <td><asp:Label id="label" runat="server" Text="<%# Container.DataItem %>" /></td>
              </tr>
            </ItemTemplate>

            <EmptyDataTemplate>
              <div>Nothing to see here...</div>
            </EmptyDataTemplate>

          </asp:ListView>

        </form>

      </body>

    </html>