protected void setColor(HttpServletRequest req, String color) throws ServletException {
req.getSession().setAttribute("color", color);
}
protected String getColor(HttpServletRequest req) throws ServletException {
HttpSession session = req.getSession(/* create */ false);
if (session == null) return null;
return (String) session.getAttribute("color");
}
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType("text/plain");
writeSelectMessage(req.getParameter("color"), resp.getWriter());
setColor(req, req.getParameter("color"));
}