Consuming muiltipart POST data in JAX-RS REST Service

Question

I have a jax-rs REST service, using JEE 7 (deployed in glassfish), which has a method to process HTTP POST on the resource:

@POST
@Path(value="{dId}")
@Consumes(MediaType.MULTIPART_FORM_DATA)
@Produces(MediaType.APPLICATION_JSON)
public Response sendStatus(@Context HttpServletRequest request)

I try to extract the multipart data as:

Collection<Part> parts = request.getParts();
if(parts==null || parts.isEmpty()){
        lg.warn("Empty/non-existent parts in request body!");
        return sendBadRequestError(sp);
}

I then try to simulate a client multipart POST request, using RestClient(from wiztools.org), with atleast 2 parts of different content-types ( boundary delimiter is automatically set by the RESTClient tool).

I verify in wireshark that its a proper request that is sent from the RESTClient( no malformed packet etc).

However, all the request seems to hit the block containing the Empty/non-existent parts in request body message, indicating there were no parts found in the request.

I searched around in Stackoverflow many times before posting, and all the examples/solutions relate to use-case where one is uploading a file/image, which is not the case am dealing with.

My rest service just consumes a multipart request, which can consist of one part with JSON data, another part with simple string or other JSON data.

Is there something am missing - please help?.Is there someother technique to parse the multipart data that hits a REST service?

Please advice.

Thanks. J

Answer 1

Thanks to pointers from @peeskillet, I used the Jersey multipart API to get the handle to the multipart entities.

Just so that it may help others bumping into the same problem, am listing the complete solution:

1. Enable "MultiPart" capability for your app in the container. This is necessary for availability of the required readers/writers. How to do this is clearly articulated in Jersey 2 injection source for multipart formdata

2. The resource method then is defined as

   @POST
   @Path(value="{dId}")
   @Consumes(MediaType.MULTIPART_FORM_DATA)
   @Produces(MediaType.APPLICATION_JSON)
   public Response sendStatus(FormDataMultiPart multipart){
   ....
   ...
      Map<String, List<FormDataBodyPart>> parts = multipart.getFields();
      if(parts==null || parts.isEmpty()){
          lg.warn("Empty/non-existent parts in request body!");
          return sendBadRequestError(sp);
      }
   
      for(List<FormDataBodyPart> p: parts.values()){
            FormDataBodyPart bp = p.get(0);
            lg.info("\t body part name {}",bp.getName());
            lg.info("\t body part value {}",bp.getValue());            
             ....//do your real stuff here
       }
   
    }
   

And bingo it works!.

Also a side note: when using the RESTClient GUI tool, make sure you don't explicitly set the Content-Type and Boundary, since the tool set its automatically.

Hope this helps someone.

ps: How do I vote for peeskillet's answer?