Enable Spring AOP or AspectJ

Question

This is following on from this question:

Spring autowired bean for @Aspect aspect is null

My initial understanding was that when using Spring AOP, classes annotated with @Aspect are created as spring managed beans, so dependency injection would work as normal. However it seems that an object with the @Aspect annotation is created as a singleton outside the spring container, hence me having to configure it in XML like so in order to enable it as a spring managed bean:

<bean id="aspect" class="com.mysite.aspect" factory-method="aspectOf" />

This has now completely confused me. I thought the following configuration would use spring AOP:

<context:component-scan base-package="com.mysite.aspectPackage"/>
<aop:aspectj-autoproxy/>

So it would scan for @Aspect annotations using component-scan creating aspect beans, and then autoproxy would create a beanPostProcessor which proxies all beans within my context with the appropriate advice. I then thought to enable aspectJ I would need a completely different XML configuration (which incidentally I can't seem to find an example of in the documentation). It would be this configuration that uses aspectJ to create aspects that would be outside of my container or which work by manipulating bytecode rather than proxying.

Note
This is not a question on the difference between spring AOP and aspect J, this is well articulated here:

Spring AOP vs AspectJ

Answer 1

@Component will create 2 instances, one inside the Spring container, one inside the aspectJ container.

use @Configurable to allow spring to manage dependency injection etc. for your class when instantiated by the aspectj container.

@Aspect is an aspectj style annotation that is supported by spring-aop, where runtime weaving is used to handle interception etc.

Compile-time weaving allows you to disregard the use of as pointcuts will be present in the bytecode, this is done via the aspectj compiler (See https://www.mojohaus.org/aspectj-maven-plugin/ for mvn integration) .

Whether you use the aspectj compiler or spring-aop makes no difference, it wont create your aspect as a managed bean in the way you want unless you use factory / configurable.

Aspectj configuration is, strictly, the pointcut definitions etc that will be present inside your class.

Answer 2

@Aspect is not a spring annotation, and it is not detected by component-scan. So you have to register it somehow as a spring bean. The aspectOf solution works. You can also try

@Aspect
@Component