如何从checkbox onchange事件获取id

这是我的servlet页面。我正在尝试从checkbox onchange事件中获取品牌id。但这行不通。谁能帮帮我吗。

public class servlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=UTF-8");

        try {
            Session s1 = Connection.NewHibernateUtil.getSessionFactory().openSession();
            Criteria c = s1.createCriteria(Brand.class);
            List<Brand> list = c.list();
            for (Brand brand : list) {
                PrintWriter out = resp.getWriter();
                out.println("<input type=\"checkbox\"> <onchange=\"self.location.href=index.jsp?b=" + brand.getIdbrand() + ">" + brand.getName() + "<br>");
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}