code-snippet2.java

public final class HandleErrors extends SimpleFilter<Request, Response> {
    @Override
    public Future<Response> apply(Request req, Service<Request, Response> service) {
        return service.apply(req).handle(new ExceptionalFunction<Throwable, Response>() {
            @Override
            public Response applyE(Throwable in) {
                Response resp = Response.apply();
                ChannelBuffer content = ChannelBuffers.wrappedBuffer(in.getMessage().getBytes());

                if (in instanceof NumberFormatException) {
                    resp.setStatus(HttpResponseStatus.BAD_REQUEST);
                    resp.setContent(content);

                    return resp;
                }
                in.printStackTrace();
                resp.setStatus(HttpResponseStatus.INTERNAL_SERVER_ERROR);
                resp.setContent(content);

                return resp;
            }
        });
    }
}