protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub

    request.getSession().setAttribute("key",calculate);
    request.getSession().setAttribute("key2",givediscount);

     RequestDispatcher dispatcher = request
             .getRequestDispatcher("cart.jsp");
     dispatcher.forward(request, response);

<TD><%= id %></TD>
            <TD><%= name%></TD>
            <TD><%= quantity %></TD>
            <TD> <%=session.getAttribute("key")%> </TD>
            <TD><%=session.getAttribute("key2")%> </TD>
            <TD><input type="submit" value="BUY" /></TD>