Enterprise Java

Setting basic response http headers for REST resources on a simple Vertx Rest based app

I am new to Vert.x but as a Java developer (die hard) I find it much more enjoyable and promising comparing to NodeJS or whatever – Reactor based frameworks/libraries. So I was going through implementing a very simple Restful API, using Vert.x.

My problem for today is that I wanted to include some certain HttpHeaders in most (all) of my , responses. For example set the Content-type to “application/json”. In the future maybe add some others.

I was kind of wondering around as a Vert.x newbie, then I kind of realized that what is was eventually suggested in this blog post (See the use of BodyHandler) would actually work for me.

So I had my main VertxMain java app where I register my MyWebVerticleApp.

package com.javapapo.vertxweb;

import io.vertx.core.Vertx;
import io.vertx.core.VertxOptions;

 * Created by <a href="mailto:javapapo@mac.com">javapapo</a> on 15/11/15.
public class VertxEngineMain {
    public static void main(String[] args) {
        VertxOptions opts = new VertxOptions();
        Vertx vertx = Vertx.vertx(opts);
        vertx.deployVerticle(new MyWebVerticleApp());


Then I have created a small handler, I call it BaseResponseHandler, that eventually adds the HttpHeader in my responses.

package com.javapapo.vertxweb.handlers;

import io.netty.handler.codec.http.HttpResponse;
import io.vertx.core.Handler;
import io.vertx.core.http.HttpHeaders;
import io.vertx.core.http.HttpServerRequest;
import io.vertx.core.http.HttpServerResponse;
import io.vertx.ext.web.RoutingContext;

 * Created by <a href="mailto:javapapo@mac.com">javapapo</a> on 27/11/15.
public class BaseResponseHandler implements Handler<RoutingContext>{

    public void handle(RoutingContext context) {
        HttpServerResponse response = context.response();
        response.putHeader(HttpHeaders.CONTENT_TYPE.toString(), "application/json");
        //other stuff!


Then in my MyWebVerticle I just register the handler to be invoked all the time, in the router chaining.

package com.javapapo.vertxweb;

import com.javapapo.vertxweb.handlers.BaseResponseHandler;
import com.javapapo.vertxweb.handlers.StatusHandler;
import io.vertx.core.AbstractVerticle;
import io.vertx.core.Future;
import io.vertx.core.http.HttpServer;
import io.vertx.core.http.HttpServerResponse;
import io.vertx.ext.web.Route;
import io.vertx.ext.web.Router;
import io.vertx.ext.web.handler.BodyHandler;

 * Created by <a href="mailto:javapapo@mac.com">javapapo</a> on 16/11/15.
public class MyWebVerticleApp extends AbstractVerticle {
    public void start(Future<Void> fut) {
        HttpServer server = vertx.createHttpServer();
        Router router = Router.router(vertx);
        //enable the base response handler overall!
        router.route().handler(new BaseResponseHandler());
        router.route("/status/").handler(new StatusHandler());

Paris Apostolopoulos

Paris is a senior software engineer focusing on J2EE development, loves Business process modelling and is keen on software quality challenges. He is passionate about Java and Java communities. He is a co-founder and administrator of the first Java User Group in greece(JHUG.gr) and occasional speaker on meet-ups and seminars and regular blogger. For his contributions and involvement on the Java community he has been awarded the title of Java Champion in 2007 by Sun Microsystems.
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