filter 取session值有关问题

HttpServletRequest httpRequest = (HttpServletRequest) request;httpRequest.getSession().setAttribute("login", account);chain.doFilter(httpRequest, httpResponse);

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String userAccount = request.getParameter("userAccount");        respons.setContentType("text/html; charset=UTF-8");        try        {            out = respons.getWriter();        }        catch (IOException e)        {            e.printStackTrace();        }        //注销session        HttpSession session = request.getSession();            }

HttpServletRequest httpRequest = (HttpServletRequest)request;Object login = httpRequest.getSession().getAttribute("login");