我用shiro+redis做session共享，用户登陆后重启服务器无法获取ServletContext中得值
用户登陆后将用户得sessionID与用户绑定

private void saveLoginSession(String username){
        ServletContext application = Mvcs.getHttpSession().getServletContext();
        Map<String, String> loginUsers = (Map<String, String>) application
                .getAttribute("loginUsers");

        String sessionId = Mvcs.getHttpSession().getId();
        log.debug("sessionId=============:" + sessionId);
        log.debug("loginUsers:" + loginUsers);
        if (loginUsers == null || loginUsers.size() == 0) {
            loginUsers = new HashMap<>(10);
            loginUsers.put(username, sessionId);
            application.setAttribute("loginUsers", loginUsers);
        } else {
            loginUsers.put(username, sessionId);
        }
    }

再重启服务器后判断用户登陆无法获取ServletContext中设置得loginUsers，但是可以获取Attribute(Auth.FRONT_KEY)这个设置得值

public static Boolean isLogin() {
        HttpSession session = Mvcs.getHttpSession();
        ServletContext application = session.getServletContext();
        if (application == null) {
            return false;
        }
        Map<String, String> loginUsers = (Map<String, String>) application.getAttribute("loginUsers");
        if (loginUsers == null || loginUsers.size() == 0) {
            return false;
        }
        String sessionId = session.getId();
        Auth auth = (Auth) session.getAttribute(Auth.FRONT_KEY);
        if (auth == null) {
            return false;
        }
        String userSessionId = loginUsers.get(auth.name);
        if (userSessionId != null && !sessionId.equals(userSessionId)) {
            session.removeAttribute(Auth.FRONT_KEY);
            return false;
        }
        return true;
    }