无法使用Guice和Vertx将相同的实例注入多个Verticle

Question

I have 3 vertx verticles.

I created class AImpl which implements class A as follows

 @Singleton
public class AImpl implements A {


    public LocationServiceImpl() {
        System.out.println("initiated once");

    }

 public void doSomething(){..}

Verticle 1 looks like this:

public class MyVerticle1 extends AbstractVerticle {
...
 @Inject
    private A a;


 @Override
    public void start(Future<Void> fut) {
 Guice.createInjector(new AppInjector()).injectMembers(this);
  a.doSomething(..);

..}

MyVerticle2 and MyVerticle3 looks the same.

Guice code:

public class AppInjector extends AbstractModule {


    public AppInjector() {
    }


    @Override
    protected void configure() {   
 bind(A.class).to(AImpl.class).in(Singleton.class);

    }

Now when I run vertx I can see that I get 3 different instances of AImpl:

 public static void main(String[] args) throws InterruptedException {
        final Logger logger = Logger.getLogger(StarterVerticle.class);
        ClusterManager mgr = new HazelcastClusterManager();
        VertxOptions options = new VertxOptions().setClusterManager(mgr);
        Vertx.clusteredVertx(options, res -> {
            if (res.succeeded()) {
                Vertx vertx = res.result();
                vertx.deployVerticle(new MyVerticle1());
                vertx.deployVerticle(new MyVerticle2());
                vertx.deployVerticle(new MyVerticle3());
                logger.info("Vertx cluster started!");
            } else {
                logger.error("Error initiating Vertx cluster");
            }
        });

console:

2015-09-15 16:36:15,611 [vert.x-eventloop-thread-0] INFO   - Vertx cluster started!
initiated once
initiated once
initiated once

What am I abusing with guice? why I dont get the same AImpl instance?

Thanks, ray.

Answer 1

You are using guice the wrong way. You are creating the MyVerticle instances via new and create the injector inside their start message. Thus you end up with 3 injectors, each holding a singleton.

You have to create the injector once in your main() method and then let guice handle the creation of the MyVerticles:

Injector injector = Guice.createInjector(....);
...
vertx.deployVerticle(injector.getInstance(MyVerticle1.class);

now the injector creates only one instance for AImpl and reuses it for all @Inject AImpl locations. Remove the injectors from your start methods completely.

2 rules of thumb when working with guice:

1. avoid using new
2. try to use only one single injector located in your main() method