Asp.net file upload control using ajax(update panel)

Today i want to show file upload control using ajax

here is .aspx 

 <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">

    </asp:ToolkitScriptManager>

    <asp:UpdatePanel ID="UpdatePanel1" runat="server">

     <Triggers>

        <asp:PostBackTrigger ControlID="Button1"/>

    </Triggers>

  <ContentTemplate>

    <asp:FileUpload ID="FileUpload1" runat="server" />

      <asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />

    </ContentTemplate>

      </asp:UpdatePanel>

And at .cs page you can get like below.

 protected void Button1_Click(object sender, EventArgs e)

    {

        string a = FileUpload1.PostedFile.FileName;

    }