Question

When you use @Autowired in a spring @Component, spring determines autowire candidates for every instantiation of the component, which is really not good when you use @Request/@Session scoped web stuff. Why doesn’t spring just make a bean definition within the ApplicationContext once and re-use that ? Is there any way to make it do so ?

Answer 1

AutowiredAnnotationBeanPostProcessor is a BeanPostProcessor, not a BeanFactoryPostProcessor, so it can’t edit Bean definitions, by design. Implementing that differently would break expected functionality:

public class MyBean{

    @Autowired(required=false)
    public void setOtherBean(OtherBean o){this.otherBean=o;}
    private OtherBean otherBean;

}

If no OtherBean instance is available, none will be wired, but as soon as one becomes available (and I can easily programatically wire one), the next MyBean instance (if scope is not singleton) will get the new OtherBean (which was not available before).

I’m not saying this a use case I have encountered before, but it’s a valid use case and it would break if things worked the way you suggest that they should.