Understanding Spring AOP Proxy Creation and Common Pitfalls

Spring AOP weaves aspect code into bean methods at runtime, effectively using the proxy pattern.

The article shows a case where a CouponService class's deposit() method is not intercepted because internal calls via this bypass the proxy.

It explains that Spring creates proxies either with JDK dynamic proxies (interface‑based) or CGLIB subclass proxies, and that only beans obtained from the container are proxied.

The core component AnnotationAwareAspectJAutoProxyCreator (a BeanPostProcessor) runs after bean initialization, invoking wrapIfNecessary to replace the original bean with a proxy when needed.

To enable proxy creation, @EnableAspectJAutoProxy (or @EnableAspectJAutoProxy(exposeProxy = true)) must be configured, allowing the current proxy to be accessed via AopContext.currentProxy().

Two common solutions are presented: injecting the bean itself with @Autowired so that the injected reference is the proxied instance, or exposing the proxy through AopContext after setting exposeProxy=true.

Finally, the article emphasizes that only objects created by Spring’s dynamic proxy mechanism can benefit from AOP, and shows the necessary configuration changes.