Java RESTeasy return PDF IMAGE file.

Media.java

@Path("media")
@Stateless
public class MediaRestService {
    private final static org.slf4j.Logger log = LoggerFactory.getLogger(MediaRestService.class);
    @EJB
    private ThumbnailServices thumbnailService;
    @EJB
    private DocumentServices docServices;

    
    @Path("document/{id}/thumbnail")
    @GET
    @Produces("image/jpg")
    public Response getThumbnailOfDocument(@PathParam("id") String id) {
        try {
            String base64Content = thumbnailService.getThumbnail(id);
            byte[] imageData = IOUtils.convertToBytesFromBase64(base64Content,"jpg");
            return Response.ok(new ByteArrayInputStream(imageData)).build();
        } catch (ConversionException | EntityNotFoundException | IOException ex) {
            log.debug("Error: " + ex.getMessage());
            return Response.ok().build();
        }
    }
    
    @GET
    @Path("document/{id}/file")
    @Produces("application/pdf")
    public Response findContentBase64(@PathParam("id") String documentId) {
        byte[] bytes = null;
        try {
            try {
                bytes = org.apache.commons.io.IOUtils.toByteArray(docServices.fileContent(documentId));
            } catch (UnknownHostException | EntityNotFoundException ex) {
               log.error("Error: " + ex.getMessage());
            }
        } catch (ConversionException | IOException ex) {
             log.error("Error: " + ex.getMessage());
        }
        return Response.ok(new ByteArrayInputStream(bytes)).build();
    }
}

The fundamental is return the file as binary and set header for as file type. Browser will automatically open the file.