Content type 'null' not supported returned by Spring RESTTemplate getForObject method

Question

I have a simple REST method in a Spring MVC controller as follows which has a signature of:

@RequestMapping(value="/person/{personId}", method=RequestMethod.GET) public @ResponseBody Object getPerson(@PathVariable("personId") String personId) {
... }

The output is type Object because several different data types are returned from this method.

When called from a test program within the Spring MVC application, as follows:

private static void getPerson() {
    logger.info(Rest.class.getName() + ".getPerson() method called."); 

    RestTemplate restTemplate = new RestTemplate();

    Person person = restTemplate.getForObject("http://localhost:8080/Library/rest/person/1", Person.class);   

    ObjectMapper responseMapper = new ObjectMapper(); 
    ...
    }

The response is Content type 'null' not supported and the call fails.

Can anyone advise why?

When called from a test program in another application which doesn't use Spring but which makes HTTP GET requests, the controller method is called properly and works.

Solution

You can try this:

HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
requestFactory.setReadTimeout(VERSION_CHECK_READ_TIMEOUT);
RestTemplate template = new RestTemplate(requestFactory);
Person person = restTemplate.getForObject("http://localhost:8080/Library/rest/person/1", Person.class);

If above doesn't work you can try using a Entity approach like:

  RestTemplate restTemplate = new RestTemplate();

  // Prepare acceptable media type
  List<MediaType> acceptableMediaTypes = new ArrayList<MediaType>();
  acceptableMediaTypes.add(MediaType.APPLICATION_XML); // Set what you need

  // Prepare header
  HttpHeaders headers = new HttpHeaders();
  headers.setAccept(acceptableMediaTypes);
  HttpEntity<Person> entity = new HttpEntity<Person>(headers);

  // Send the request as GET
  try {
      ResponseEntity<PersonList> result = restTemplate.exchange("http://localhost:8080/Library/rest/person/1", HttpMethod.GET, entity, PersonList.class);
      // Add to model
      model.addAttribute("persons", result.getBody().getData());

  } catch (Exception e) {
      logger.error(e);
  }

There are many useful examples here.

Hope to help

Comments

[Mr Morgan]

Thanks but concerning the first, where does VERSION_CHECK_READ_TIMEOUT live? And for the second, the parameter ("") causes bother.

[Federico Piazza]

@MrMorgan sorry, check again.

[Mr Morgan]

I have no such getData() method in the Person class. However, despite everything the code still returns Content type 'null' not supported which is odd given that I've set the media type to JSON. –