在ajax的異常處理中，直接返回IMoocJSONResult是不行的，會再拋出一個

Error resolving template template might not exist or might not be accessible 的異常，而不是我們預想的byZero的異常，這時候需要使用MappingJackson2HttpMessageConverter把IMoocJSONResult手動寫入 HttpServletResponse中。

?

private static final String ERROR_VIEW = "error";

@Autowired

private MappingJackson2HttpMessageConverter jsonConverter;

???

@ExceptionHandler(value = Exception.class)

public Object error(HttpServletRequest request, HttpServletResponse response, Exception e) throws HttpMessageNotWritableException, IOException {

if(isAjax(request)) {

MyJSONResult result = MyJSONResult.errorException(e.getMessage());

??????????? jsonConverter.write(result, MediaType.APPLICATION_JSON, new ServletServerHttpResponse(response));

??????????? return null;

} else {

ModelAndView mav = new ModelAndView();

mav.addObject("exception",e);

mav.addObject("url", request.getRequestURL());

mav.setViewName(ERROR_VIEW);

return mav;

}

}