[FIXED] Spring boot controller content negotiation

Issue

I have a simple REST controller written in a Spring-boot application but I am not sure how to implement the content negotiation to make it return JSON or XML based on the Content-Type parameter in the request header. Could someone explain to me, what am I doing wrong?

Controller method:

@RequestMapping(value = "/message", method = RequestMethod.GET, produces = { MediaType.APPLICATION_JSON_VALUE, MediaType.APPLICATION_XML_VALUE })
  public Message getMessageXML(@RequestParam("text") String text) throws Exception {
    Message message = new Message();
    message.setDate(new Date());
    message.setName("Test");
    message.setAge(99);
    message.setMessage(text);

    return message;
  }

I always get JSON when calling this method (even if I specify the Content-Type to be application/xml or text/xml).

When I implement two methods each with different mapping and different content type, I am able to get XML from the xml one but it does not work if I specify two mediaTypes in a single method (like the provided example).

What I would like is to call the \message endpoint and receive

• XML when the Content-Type of the GET request is set to application/xml
• JSON when the Content-Type is application/json

Any help is appreciated.

EDIT: I updated my controller to accept all media types

@RequestMapping(value = "/message", method = RequestMethod.GET, produces = { MediaType.APPLICATION_JSON_VALUE, MediaType.APPLICATION_XML_VALUE }, consumes = MediaType.ALL_VALUE)
  public Message getMessageXML(@RequestParam("text") String text) throws Exception {
    Message message = new Message();
    message.setDate(new Date());
    message.setName("Vladimir");
    message.setAge(35);
    message.setMessage(text);

    return message;
  }

Solution

You can find some hints in the blog post @RequestMapping with Produces and Consumes at point 6.

Pay attention to the section about Content-Type and Accept headers:

@RequestMapping with Produces and Consumes: We can use header Content-Type and Accept to find out request contents and what is the mime message it wants in response. For clarity, @RequestMapping provides produces and consumes variables where we can specify the request content-type for which method will be invoked and the response content type. For example:

@RequestMapping(value="/method6", produces={"application/json","application/xml"}, consumes="text/html")
@ResponseBody
public String method6(){
    return "method6";
}

Above method can consume message only with Content-Type as text/html and is able to produce messages of type application/json and application/xml.

You can also try this different approach (using ResponseEntity object) that allows you to find out the incoming message type and produce the corresponding message (also exploiting the @ResponseBody annotation)

Answered By - abarisone
Answer Checked By - Marilyn (JavaFixing Volunteer)