/**
  * 修改主流程
  *
  * @param session
  * @param model
  * @param document
  * @return
  */
 @RequestMapping(params = "method=modify", method = RequestMethod.POST)
 public String modify(HttpSession session, Model model, Document document) {
   User user = (User) session.getAttribute("user");
   if (user != null) {
     document.setUserid(user.getUserid());
     documentService.update(document);
     model.addAttribute("user", user);
     model.addAttribute("msg", "更新成功!");
     return "redirect:document?method=list";
   } else return "error";
 }