Agfdhyk

My application structure is like

I created an annotation as below:-

@Retention(RetentionPolicy.RUNTIME)

@Target(ElementType.METHOD)

public @interface SampleAnnotation {

}

Then created a Sample Interceptor:

public class SampleInterceptor implements MethodInterceptor {



    private static final Logger logger = LoggerFactory.getLogger(SampleInterceptor.class);



    @Inject

    SampleService sampleService; // this is not working



    public Object invoke(MethodInvocation invocation) throws Throwable {

        logger.info("SampleInterceptor : Interceptor Invoked");

        Object result = invocation.proceed();

        Observable<List<Sample>> observable = (Observable<List<Sample>>) result;

        SampleSender sender = null;

        List<Sample> sampleList = observable.toBlocking().first();



        for(Sample sample : sampleList ) {

            sender = new SampleSender();

            sender.setBoolean(sample.isBoolean());

            logger.info("Pushing Data into Sender");

            sampleService.insert(String.join("_", "key", "value"), sender); // here getting NullPointerException because sampleService is null

        }

        return result;

    }

}

Then I created a GuiceModule as below:-

public class SampleModule extends AbstractModule {

    @Override

    protected void configure() {

        bindInterceptor(Matchers.any(), Matchers.annotatedWith(SampleAnnotation.class), new SampleInterceptor());

}

}

Class in which I am using the above annotation is

// This class also have so many method and this was already declared and using in another services, I created a sample class here

class SampleClassForInterceptor {



      // this sampleMethod() is not a new method, its already created, 

      // now I am adding annotation to it, because after finishing this functionality, 

      // I want something should be done, so created annotation and added here

      @SampleAnnotation

      public Observable<List<Sample>> sampleMethod() {

            Sample sample = new Device();

            sample.setName("*** 7777");

            sample.setBoolean(true);

            List<Sample> list = new ArrayList<>();

            list.add(sample);

            Observable<List<Device>> observable = Observable.just(list);

            return observable;

      }

}

I have a RestModule using which I am binding SampleClassForInterceptor as follows

public final class RestModule extends JerseyServletModule {

    // other classes binding

    bind(SampleClassForInterceptor.class).in(Scopes.SINGLETON);

    // other classes binding

    install(new SampleModule());

}

Now I have a bootsrap class in which I am binding RestModule

public class Bootstrap extends ServerBootstrap {

   binder.install(new RestModule());

}

Usage:-

@Path("service/sample")

public class SampleRS {

    @Inject

    SampleClassForInterceptor sampleClassForInterceptor;



    public void someMethod() {

        sampleClassForInterceptor.sampleMethod();

    }

}

My interceptor functionality is started executing before executing sampleMethod() of SampleClassForInterceptor class, then after executing the sampleMethod() again coming back to Interceptor, now here I have a code snippet which will insert the result(which we got from sampleMethod()). This is where I am getting NullPointerException, I checked code and found that SampleService object not getting injected and its value is null

Note: I am using Microservices with RESTFUL services concept

when I used requestInjection in the SampleModule, then SampleService got injected inside interceptor i.e I modified the SampleModule code as follows

public class SampleModule extends AbstractModule {

     @Override

     protected void configure() {

         SampleInterceptor interceptor = new SampleInterceptor();

         requestInjection(interceptor);

         bindInterceptor(Matchers.any(), Matchers.annotatedWith(SampleAnnotation.class), interceptor);

     }

}