jersey + grizzly + hk2:依赖注入，但不注入资源

Now you can still use your locator outside of Jersey. Honestly though, in this case, you could not involve Jersey at all and just keep your own locator, and just register the EntityManagerProvider with both Jersey and your ServiceLocator. I don't see it really making much difference, except for the extra line of code. Functionally, I don't see any change.

要了解有关 HK2 的更多信息，我强烈建议您仔细阅读 用户指南.您将了解很多关于 Jersey 的幕后知识，并了解可以合并到 Jersey 应用程序中的功能.

To learn more about HK2, I highly recommend thoroughly going through the user guide. You'll learn a lot about what goes on under the hood with Jersey, and also learn about features that you can incorporate into a Jersey application.

以下是测试的完整重构.我并没有真正改变太多.我所做的任何更改都在上面进行了讨论.

Below is the complete refactor of your test. I didn't really change much. Any changes I made are pretty much discussed above.

public class DependencyInjectionTest {

    private final ServiceLocatorFactory locatorFactory
            = ServiceLocatorFactory.getInstance();
    private ServiceLocator serviceLocator;

    private final static String BASE_URI = "http://localhost:8888/";
    private final static String OK = "OK";
    private HttpServer server;
    private ExecutorService backgroundService;

    public class EntityManagerProvider extends AbstractBinder
            implements Factory<EntityManager> {

        private final EntityManagerFactory emf;

        public EntityManagerProvider() {
            emf = Persistence.createEntityManagerFactory("derbypu");
        }

        @Override
        protected void configure() {
            bindFactory(this).to(EntityManager.class);
            System.out.println("EntityManager binding done");
        }

        @Override
        public EntityManager provide() {
            EntityManager em = emf.createEntityManager();
            System.out.println("New EntityManager created");
            return em;
        }

        @Override
        public void dispose(EntityManager em) {
            em.close();
        }
    }

    public class BackgroundTask implements Callable<String> {

        @Inject
        EntityManager em;

        @Override
        public String call() throws Exception {
            System.out.println("Background task started");
            Assert.assertNotNull(em);   // will throw exception

            System.out.println("EntityManager is not null");
            return OK;
        }
    }

    public class ServiceLocatorFeature implements Feature {

        @Override
        public boolean configure(FeatureContext context) {
            ServiceLocator jerseyLocator
                    = org.glassfish.jersey.ServiceLocatorProvider
                            .getServiceLocator(context);

            System.out.println("ServiceLocators are the same: "
                    + (jerseyLocator == serviceLocator));

            return true;
        }
    }

    @Path("/test")
    public static class JerseyResource {

        @Inject
        EntityManager em;

        @GET
        @Produces(MediaType.TEXT_PLAIN)
        public Response doGet() {
            System.out.println("GET request received");
            Assert.assertNotNull(em);

            System.out.println("EntityManager is not null");
            return Response.ok()
                    .entity(OK)
                    .build();
        }
    }

    @Before
    public void setUp() {
        serviceLocator = locatorFactory.create("TestLocator");
        ServiceLocatorUtilities.bind(serviceLocator, new EntityManagerProvider());

        System.out.println("Setting up");
        ResourceConfig config = new ResourceConfig();
        config.register(new ServiceLocatorFeature());
        //config.register(new EntityManagerProvider());
        config.register(JerseyResource.class);
        // can't find a better way to register the resource
        //config.registerInstances(JerseyResource.class);   

        server = GrizzlyHttpServerFactory.createHttpServer(
                URI.create(BASE_URI),
                config, serviceLocator
        );

        backgroundService = Executors.newSingleThreadScheduledExecutor();
    }

    @After
    public void tearDown() {
        System.out.println("Shutting down");
        server.shutdownNow();
        backgroundService.shutdownNow();
    }

    @Test
    public void testScheduledBackgroundTask() throws Exception {
        Assert.assertTrue(server.isStarted());

        BackgroundTask task = new BackgroundTask();
        serviceLocator.inject(task);
        Future<String> f = backgroundService.submit(task);
        System.out.println("Background task submitted");

        try {
            Assert.assertEquals(OK, f.get());   // forces Exception
        } catch (ExecutionException | InterruptedException ex) {
            System.out.println("Caught exception " + ex.getMessage());
            ex.printStackTrace();

            Assert.fail();
        }
    }

    @Test
    public void testBackgroundTask() throws Exception {
        Assert.assertTrue(server.isStarted());

        BackgroundTask task = new BackgroundTask();
        serviceLocator.inject(task);
        System.out.println("Background task instantiated");

        Assert.assertEquals(OK, task.call());
    }

    @Test
    public void testResource() {
        Assert.assertTrue(server.isStarted());

        Client client = ClientBuilder.newClient();
        WebTarget target = client.target(BASE_URI);

        Response r = target.path("test")
                .request()
                .get();
        Assert.assertEquals(200, r.getStatus());
        Assert.assertEquals(OK, r.readEntity(String.class));
    }
}

我可能要提到的另一件事是应用程序只需要一个 EntityManagerFactory.创建它的成本很高，并且每次需要 EntityManager 时创建一个并不是一个好主意.查看一种解决方案此处.

Another thing I might mention is that you should need only one EntityManagerFactory for the application. It's expensive to create, and creating one every time the EntityManager is needed is not a good idea. See one solution here.

这篇关于jersey + grizzly + hk2:依赖注入，但不注入资源的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！