@RequestMapping(
     value = "/json/write/{id}.json",
     produces = {MediaType.APPLICATION_JSON_VALUE + ";charset=UTF-8"})
 @ResponseBody
 @ResponseStatus(HttpStatus.OK)
 public Demo handleWriteJSON(@PathVariable("id") Long id, Model model) {
   logger.info("handleWriteJSON  id==" + id);
   Demo demo = demoService.getById(id);
   return demo;
 }
  @RequestMapping(
      value = "/xml/write/{id}.xml",
      produces = {MediaType.APPLICATION_XML_VALUE + ";charset=UTF-8"})
  @ResponseBody
  @ResponseStatus(HttpStatus.OK)
  public Demo handleWriteXML(@PathVariable("id") Long id, Model model) {
    logger.info("handleWriteXML  id==" + id);
    Demo demo = demoService.getById(id);

    // @DeclareParents
    DemoDeclareParentsService declareParents = (DemoDeclareParentsService) demoService;
    logger.info("@DeclareParents===" + declareParents.printString("@DeclareParents is ok"));

    return demo;
  }