It is provider class is responsible to Marshall the Java bean into JSON object

BookJsonMarshaller

@Provider
@Produces(MediaType.APPLICATION_JSON)
public class BookJsonMarshaller implements MessageBodyWriter<Book> {

	@Override
	public long getSize(Book book, Class<?> clazz, Type type, Annotation[] annotations, MediaType mediaType) {
		return -1;
	}

	@Override
	public boolean isWriteable(Class<?> clazz, Type type, Annotation[] annotations, MediaType mediaType) {
		return clazz == Book.class;
	}

	@Override
	public void writeTo(Book book, Class<?> clazz, Type type, Annotation[] annotations, MediaType mediaType,
			MultivaluedMap<String, Object> valueMap, OutputStream stream) throws IOException, WebApplicationException {
		
		JsonObject jsonObject = Json.createObjectBuilder()
				.add("title", book.getTitle())
				.add("author", book.getAuthor()).build();
		
		DataOutputStream outputStream = new DataOutputStream(stream);
		outputStream.writeBytes(jsonObject.toString());
	}
}