如何在ASP成员中使用LogOut

protected void Button2_Click(object sender, System.EventArgs e) //logout
{
    if (System.Web.HttpContext.Current.User.Identity.IsAuthenticated)
    {
        System.Web.HttpContext.Current.Session.Abandon(); // it isn't logout >_<
    }
}
protected void Button2_Click(object sender, Sys