问题
The docs explain that, the LTW has to enabled either through the use of <context:load-time-weaver/> xml instruction or the use of @EnableLoadTimeWeaving annotation. However, I have done neither, but I still see that aspects are woven correctly in my projects!
- In this case, I don't think they are woven at compile-time (but are they?), so it's surely got to be load-time-weaving?
- Even if that's the case, how does it automatically choose to weave aspects in during load-time? Shouldn't the aspects remain unwoven if they are not turned on using one of the ways mentioned above as the docs say?
- I've got the aspectj-weaver in my classpath, but that can't be enough to choose either of these weaving types anyway, can it?
回答1:
Spring AOP does not rely on AspectJ byte code weaving. It just borrows the annotations used to define aspects from the AspectJ project. It is a separately implemented framework that uses run-time proxies to implement aspects. If you have <aop:aspectj-autoproxy /> in your application context then spring is using proxies to implement supported aspects defined on beans that are in the container.
Proxies can only achieve a sub-set of the full capabilities of the actual AspectJ system, basically advice that wraps methods. Due to their nature proxies have following limitations:
- interception on external calls only (while breaching proxy boundary)
- interception on
publicmembers only (private/protectedcan't be intercepted) - unawareness to local calls (or calls with
thisorsuper)
If you want to be able to advise fields for example, you would need to enable the use of Native AspectJ.
来源：https://stackoverflow.com/questions/21472679/compile-load-time-weaving-with-spring