docs: public void validateLogin(SigninForm signinForm) {
  
          //
          // 校验用户是否存在
          //
          User user = signMgr.getUserByName(signinForm.getName());
          if (user == null) {
              throw new FieldException(SigninForm.Name, "user.not.exist", null);
          }
  
          // 校验密码
          if (!signMgr.validate(user.getPassword(), signinForm.getPassword())) {
              throw new FieldException(SigninForm.PASSWORD, "password.not.right", null);
          }
      }