Bug or Feature at Autowiring?

[Frankagile]

Hello, I got an issue about @Autwired annotation on a Bean that is accessed through a parent application context.
There are two application contexts: Parent and Child. Parent context contains bean B and child context contains bean A. A uses @Autowired on a class variable B. It looks like this:

class A {
    @Autowired
    private B myB;

    public B getMyB() {
        return myB;
    }
}

class B {}

As I get bean A from child context the @Autowiring on myB didnt work. MyB reference is null. The following testcase shows how it is working:

    public void testParentAutowiring() {

        // arrange

        // Parent
        GenericXmlApplicationContext ctxParent = new GenericXmlApplicationContext();
        BeanDefinition bd = BeanDefinitionBuilder.genericBeanDefinition(B.class).getBeanDefinition();
        ctxParent.registerBeanDefinition(B.class.getName(), bd);

        // Child
        GenericXmlApplicationContext ctxChild = new GenericXmlApplicationContext();
        ctxChild.setParent(ctxParent);
        BeanDefinition bd2 = BeanDefinitionBuilder.genericBeanDefinition(A.class).getBeanDefinition();
        ctxChild.registerBeanDefinition(A.class.getName(), bd2);

        // act
        A a = ctxChild.getBean(A.class);
        B b = ctxChild.getBean(B.class);

        // assert
        assertNotNull(a);
        assertNotNull(b);
        assertEquals(null, a.getMyB());
    }

It seems that it is legit to load beans that are registered in a parent context through child contexts by calling getBean Method but not inject them through @Autowiring. Is that a bug, works as designed or am I doing something wrong?

Thanks in advance.

[Marten Deinum]

It neither a bug nor a feature, it works as designed... Your code is just wrong...

You are using a GenericXmlApplicationContext, that expects XML for expressing dependencies, you are using annotations annotations != xml... Also you are only registering definitions, you should first refresh the contexts. Finally if you want to annotations to work before adding bean definitions register a AutowiredAnnotationBeanPostProcessor.

[Frankagile]

Thanks Marten, works perfectly fine now:

    @Test
    public void testParentAutowiring() {

        // arrange

        // Parent
        GenericXmlApplicationContext ctxParent = new GenericXmlApplicationContext();
        BeanDefinition bd = BeanDefinitionBuilder.genericBeanDefinition(B.class).getBeanDefinition();
        ctxParent.registerBeanDefinition(B.class.getName(), bd);

        // Child
        GenericXmlApplicationContext ctxChild = new GenericXmlApplicationContext();
        ctxChild.setParent(ctxParent);

        AutowiredAnnotationBeanPostProcessor abpp = new AutowiredAnnotationBeanPostProcessor();
        abpp.setBeanFactory(ctxChild.getBeanFactory());
        ctxChild.getBeanFactory().addBeanPostProcessor(abpp);

        BeanDefinition bd2 = BeanDefinitionBuilder.genericBeanDefinition(A.class).getBeanDefinition();
        ctxChild.registerBeanDefinition(A.class.getName(), bd2);

        ctxParent.refresh();
        ctxChild.refresh();

        // act
        A a = ctxChild.getBean(A.class);
        B b = ctxChild.getBean(B.class);

        // assert
        assertNotNull(a);
        assertNotNull(b);
        assertNotNull(a.getMyB());
    }