/**
  * 跳转到添加用户账号的页面.
  *
  * @param model model.
  * @return
  */
 @RequestMapping("/toAddUserAccount")
 public String toAddUserAccount(Model model) {
   DepartmentTree departmentTree = DepartmentTreeUtil.getDepartmentTree();
   model.addAttribute("departmentTree", departmentTree);
   return "admin/manageuseraccount/add_user_account";
 }