Export excel data from web user control's gridview in VB.net and ASP.net

<asp:GridView ID="GridView1" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None">

            <FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />

            <RowStyle BackColor="#EFF3FB" />

            <EditRowStyle BackColor="#2461BF" />

            <SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />

            <PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />

            <HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />

            <AlternatingRowStyle BackColor="White" />

        </asp:GridView>

    

    </div>

        <br />

        <asp:Button ID="Button1" runat="server" Font-Bold="True" OnClick="Button1_Click"

            Text="Export To Excel" />

Protected Sub Page_Load(sender As Object, e As EventArgs)


	If Not Page.IsPostBack Then


		GridView1.DataSource = BindData()


		GridView1.DataBind()
	End If

End Sub



Private ReadOnly Property ConnectionString() As String


	Get
		Return "<SQL Data Source>"
	End Get
End Property




Private Function BindData() As DataSet


	' make the query 

	Dim query As String = "SELECT * FROM tblTest"

	Dim myConnection As New SqlConnection(ConnectionString)

	Dim ad As New SqlDataAdapter(query, myConnection)

	Dim ds As New DataSet()

	ad.Fill(ds, "TestTable")

	Return ds

End Function





Protected Sub Button1_Click(sender As Object, e As EventArgs)


	Response.Clear()

	Response.AddHeader("content-disposition", "attachment;filename=FileName.xls")

	Response.Charset = ""

	Response.ContentType = "application/vnd.xls"

	Dim stringWrite As New System.IO.StringWriter()


	Dim htmlWrite As System.Web.UI.HtmlTextWriter = New HtmlTextWriter(stringWrite)

	GridView1.RenderControl(htmlWrite)

	Response.Write(stringWrite.ToString())

	Response.[End]()

End Sub

Public Overrides Sub VerifyRenderingInServerForm(control As Control)


	' Confirms that an HtmlForm control is rendered for the

	'specified ASP.NET server control at run time.

End Sub