@Reference annotation not working

Forum|Forum|7 years ago
February 13, 2018
22 replies
11318 views

I am missing something here. I am creating a new class and waht to have the resource resolver factory loaded using the @Reference annotation.

But it is not working and I am always getting an NPE when I use it.

Would someone help me to understand why? What am I missing?

Thanks.

@Component(metatype = false, immediate = true)

@Service(value = TestComponent.class)

@Properties({ @org.apache.felix.scr.annotations.Property(name = Constants.SERVICE_DESCRIPTION, value = "TestComponent"),

@org.apache.felix.scr.annotations.Property(name = Constants.SERVICE_VENDOR, value = GeneralConstants.VENDOR),

@org.apache.felix.scr.annotations.Property(name = "process.label", value = "TestComponent") })

public class TestComponentImpl implements TestComponent {

protected static final Logger LOG = LoggerFactory.getLogger( TestComponent.class);

@Reference( policy = ReferencePolicy.STATIC )

private ResourceResolverFactory resolverFactory;

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Best answer by joerghoh

Hi,

resourceResolver = new ReadServiceImpl().getResourceResolver();

That's the problem. You are constructing the ReadServiceImpl via Constructor, and in that way SCR cannot inject any references. You should make the ReadServiceImpl a service and let SCR manage its lifecycle.

Jörg

smacdonald2008

Level 10

@Reference works - we have a lot of HELPX articles that show its use. See this one where we use it with Declarative Services annotations:

Adobe Experience Manager Help | Creating an Experience Manager 6.3 Page using the Page Manager API

For info on DS annotations - see: Official OSGi Declarative Services Annotations in AEM - Adobe Experience Manager | AEM/CQ | Apache Sling

smacdonald2008

Level 10

I have personally never used the extra syntax you have:

( policy = ReferencePolicy.STATIC )

T

Tom_FoughtAuthor

Level 4

I know it works. We have many instances where it is working. I just don't understand why it isn't in this case.

smacdonald2008

Level 10

Try same code on a fresh instance that will tell us if issue is with code or AEM instance.

joerghoh

Adobe Employee

Does the reference show up at the OSGI console (/system/console/components) for this component?

Jörg

T

Tom_FoughtAuthor

Level 4

Yes. The component status is active and the resource resolver factory is satisfied.

Reference resolverFactory

["Satisfied","Service Name: org.apache.sling.api.resource.ResourceResolverFactory","Cardinality: 1..1","Policy: static","Policy Option: reluctant","Bound Service ID 981 (Apache Sling Resource Resolver Factory)"]