Spring @ExceptionHandler does not work with @ResponseBody

Question

I try to configure a spring exception handler for a rest controller that is able to render a map to both xml and json based on the incoming accept header. It throws a 500 servlet exception right now.

This works, it picks up the home.jsp:

@ExceptionHandler(IllegalArgumentException.class) public String handleException(final Exception e, final HttpServletRequest request, Writer writer) {     return "home"; } 

This does not work:

@ExceptionHandler(IllegalArgumentException.class) public @ResponseBody Map<String, Object> handleException(final Exception e, final HttpServletRequest request, Writer writer) {     final Map<String, Object> map = new HashMap<String, Object>();     map.put("errorCode", 1234);     map.put("errorMessage", "Some error message");     return map; } 

In the same controller mapping the response to xml or json via the respective converter works:

@RequestMapping(method = RequestMethod.GET, value = "/book/{id}", headers = "Accept=application/json,application/xml") public @ResponseBody Book getBook(@PathVariable final String id) {     logger.warn("id=" + id);     return new Book("12345", new Date(), "Sven Haiges"); } 

Answer 1

Your method

@ExceptionHandler(IllegalArgumentException.class) public @ResponseBody Map<String, Object> handleException(final Exception e, final HttpServletRequest request, Writer writer) 

does not work because it has the wrong return type. @ExceptionHandler methods have only two valid return types:

• String
• ModelAndView.

See http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html for more information. Here's the specific text from the link:

The return type can be a String, which is interpreted as a view name or a ModelAndView object.

In response to the comment

Thanx, seems I overread this. That's bad... any ideas how to provides exceptions automatically in xml/json format? – Sven Haiges 7 hours ago

Here's what I've done (I've actually done it in Scala so I'm not sure if the syntax is exactly correct, but you should get the gist).

@ExceptionHandler(Throwable.class) @ResponseBody public void handleException(final Exception e, final HttpServletRequest request,         Writer writer) {     writer.write(String.format(             "{\"error\":{\"java.class\":\"%s\", \"message\":\"%s\"}}",             e.getClass(), e.getMessage())); } 

Answer 2

Thanx, seems I overread this. That's bad... any ideas how to provides exceptions automatically in xml/json format?

New in Spring 3.0 MappingJacksonJsonView can be utilized to achieve that:

private MappingJacksonJsonView  jsonView = new MappingJacksonJsonView();  @ExceptionHandler(Exception.class) public ModelAndView handleAnyException( Exception ex ) {     return new ModelAndView( jsonView, "error", new ErrorMessage( ex ) ); }