Spring session 获取当前账户登录数的实例代码

session.setAttribute(FindByIndexNameSessionRepository.PRINCIPAL_NAME_INDEX_NAME, userId);

    @Autowired
    private RedisOperationsSessionRepository sessionRepository;

    public Integer fetchSameLoginNum(HttpServletRequest request) {
        int result = 0;
        HttpSession session = request.getSession();
        if (session != null) {
            String userId = (String) session.getAttribute(FindByIndexNameSessionRepository.PRINCIPAL_NAME_INDEX_NAME);
            if (StringUtils.isNotEmpty(userId)) {
                Map<String, ? extends Session> nameAndIndexValue = sessionRepository
                        .findByIndexNameAndIndexValue(FindByIndexNameSessionRepository.PRINCIPAL_NAME_INDEX_NAME, userId);
                result = nameAndIndexValue.size();
            }
        }
        return result;
    }

public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException
    {
        HttpSession hs = request.getSession();   
        //存入session
        String user = request.getParameter("user");
        hs.setAttribute("user", user);
        response.sendRedirect("index.jsp");
    }