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HK2

Danger

Guicey will get rid of HK2 usage completely in the next version and all HK2-related api and features would be removed.

All api supposed to be removed is marked as deprecated now. But there are no replacemenets provided. Please try to avoid using HK2 at all.

By default, guicey manage all extensions under guice context and only register extensions in HK2 by instance. Normally you shouldn't know about HK2 at all.

Jersey objects

Guice started before HK2 and so all jersey-related beans could be registered in guice context only with lazy providers:

binder.bind(jerseyType).toProvider(new JerseyComponentProvider(injectorProvider, jerseyType));

This provider will use jersey's InjectionManager to lookup bean:

injectionManagerInstance.getInstance(type);

See more details in jersey bindings module.

Access HK2 context from guice

Jersey's InjectionManager is available for injection inside guice context:

@Inject Provider<InjectionManager> jerseyInjector;

Provider is important because jersey starts after guice.

Note

InjectionManager is jersey's new DI-agnostic api. You can obtain HK2 ServiceLocator from it, if required: 

ServiceLocator locator = jerseyInjector.getInstance(ServiceLocator.class);

Jersey extensions

Jersey-related extensions (resources, features and providers) are registered in HK2 with lazy factories (laziness is important to respect scopes and help with cycled initialization cases (when guice beans depend on HK2 beans)):

binder.bindFactory(new GuiceComponentFactory<>(injector, guiceType)).to(guiceType)

And internally this factory will obtain instance from guice injector:

guiceInjector.getInstance(guiceType);

To see more details on how it works look jersey providers installer.

HK2 delegation

You can delegate extension instance management into HK2 with @JerseyManaged annotation:

@Provider
@JerseyManaged
public class MapperManagedByHK2 implements ExceptionMapper { ... }

Now this extension will not be instantiated by guice - HK2 will instantiate it.

Warning

Delegated beans will not be affected with guice AOP and will not see guice beans (if bridge not activated)

Tip

You can use .strictScopeControl() to make sure that beans are nto instantiated by both DI containers.

HK2 guice bridge

HK2 bridge may be required ONLY if you delegate some beans creation to HK2 (instead of guice) but beans still require guice-managed beans injection (HK2 must be able to see guice bindings).

To activate bridge:

  • Add dependency: org.glassfish.hk2:guice-bridge:2.6.1 (version must match HK2 version, used by dropwizard)
  • Enable option: .option(GuiceyOptions.UseHkBridge, true)

After that, HK2 beans could inject guice beans:

@JerseyManaged
public class HkService {

    @Inject
    private GuiceService service;
}

Use HK2 for jersey extensions

By default, guice is used to construct all extensions, including jersey related (resources, features and providers) which are registered in HK2 context as instances.

If you want to delegate all jersey extensions to HK2 then use:

GuiceBundle.builder()
    ...
   .useHK2ForJerseyExtensions()
   .build()

(It is the same as if you annotate all jersey extensions with @JerseyManaged)

After enabling, all jersey extensions will be created by HK2. Option requires HK2-guice bridge (error will be thrown if bridge is not available in classpath) to use guice services inside HK2 managed beans.

Warning

Guice AOP will work only for instances created by guice, so after enabling this option you will not be able to use aop on jersey extensions.

By analogy with @JerseyManaged, you can use @GuiceManaged to mark exceptional extensions, which must be still managed by guice.

HK2 scope debug

Special HK2DebugBundle bundle is provided to check that beans properly instantiated by guice or HK2 (and no beans are instantiated by both).

It could be activated with shortcut:

.strictScopeControl();

Affects only beans installed by installers implementing JerseyInstaller (ResourceInstaller, JerseyProviderInstaller etc) because other extensions does not support delegation to HK2.

Checks that beans annotated with @GuiceManaged are instantiated by guice and beans annotated with @JerseyManaged are created by HK2.

In default guice-first mode non annotated beans are assumed to be instantiated in guice (and so error thrown if bean created in HK2 context).

In HK2-first mode, error will be thrown if non annotated jersey extension is created by guice.

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