Declaring an Aspect
With @AspectJ support enabled, any bean defined in your application context with a
class that is an @AspectJ aspect (has the @Aspect
annotation) is automatically
detected by Spring and used to configure Spring AOP. The next two examples show the
minimal steps required for a not-very-useful aspect.
The first of the two examples shows a regular bean definition in the application context
that points to a bean class that is annotated with @Aspect
:
<bean id="myAspect" class="com.xyz.NotVeryUsefulAspect">
<!-- configure properties of the aspect here -->
</bean>
The second of the two examples shows the NotVeryUsefulAspect
class definition, which is
annotated with @Aspect
:
-
Java
-
Kotlin
package com.xyz;
import org.aspectj.lang.annotation.Aspect;
@Aspect
public class NotVeryUsefulAspect {
}
package com.xyz
import org.aspectj.lang.annotation.Aspect
@Aspect
class NotVeryUsefulAspect
Aspects (classes annotated with @Aspect
) can have methods and fields, the same as any
other class. They can also contain pointcut, advice, and introduction (inter-type)
declarations.
Autodetecting aspects through component scanning
You can register aspect classes as regular beans in your Spring XML configuration,
via @Bean methods in @Configuration classes, or have Spring autodetect them through
classpath scanning — the same as any other Spring-managed bean. However, note that the
@Aspect annotation is not sufficient for autodetection in the classpath. For that
purpose, you need to add a separate @Component annotation (or, alternatively, a custom
stereotype annotation that qualifies, as per the rules of Spring’s component scanner).
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Advising aspects with other aspects?
In Spring AOP, aspects themselves cannot be the targets of advice from other
aspects. The @Aspect annotation on a class marks it as an aspect and, hence, excludes
it from auto-proxying.
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