public String retrieveUserId(HttpServletRequest req) {
HttpSession session = req.getSession();
String userKey = "userId";
String userId = (String) session.getAttribute(userKey);
if (userId == null) {
String a = this.requestUserId();
userId = Helpers.jsonFromString(a).getString("id");
session.setAttribute(userKey, userId);
}
return userId;
}
