Building RESTful Web Services with Java EE 8

CompletionCallback

 CompletionCallback is the first callback. It is called by the JAX-RS runtime once the request is completed. The only method you need to implement is onComplete. In case of an error, you will be passed the throwable error and the "Completed processing." parameter, and we can do the required logic in here:

    static class LoggingCompletionCallback implements       CompletionCallback {        @Override        public void onComplete(Throwable throwable) {            LOGGER.log(Level.INFO, "Completed processing.", throwable);        }    }