JAX-RS MessageBodyReader

Question

I\'m learning how the MessageBodyReader method works from the providers. I see the method returns an object and I\'m not sure how to access the object from a service. Could I ge

Answer 1

You misunderstood the purpose MessageBodyReader , it is used for the following purpose :

Contract for a provider that supports the conversion of a stream to a Java type. To add a MessageBodyReader implementation, annotate the implementation class with @Provider. A MessageBodyReader implementation may be annotated with Consumes to restrict the media types for which it will be considered suitable

Example : If you have a use case where you getting come custom format other than xml/json ,you want to provide your own UnMarshaller you can use messagebody reader

    @Provider
    @Consumes("customformat")
    public class CustomUnmarshaller implements MessageBodyReader {

        @Override
        public boolean isReadable(Class aClass, Type type, Annotation[] annotations, MediaType mediaType) {
            return true;
        }


        @Override
        public Object readFrom(Class aClass, Type type, Annotation[] annotations, MediaType mediaType, MultivaluedMap multivaluedMap, InputStream inputStream) throws IOException, WebApplicationException {
            Object result = null;
            try {
                result = unmarshall(inputStream, aClass); // un marshall custom format to java object here
            } catch (Exception e) {
                e.printStackTrace();
            }

            return result;


}
}

In webservice you can use this like ..

    @POST    
    @Path("/CreateAccount")
    @Consumes("custom format")
    public Response createAccount(@Context HttpServletRequest req,Account acc) {

        saveAccount(acc); // here acc object is returned from your custom unmarshaller 
        return Response.ok().build();
    }

More Info : Custom Marshalling/UnMarshalling Example , Jersy Entity Providers Tutorial