在ajax的异常处理中，直接返回IMoocJSONResult是不行的，会再抛出一个

Error resolving template template might not exist or might not be accessible 的异常，而不是我们预想的byZero的异常，这时候需要使用MappingJackson2HttpMessageConverter把IMoocJSONResult手动写入 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;

}

}