Ankur Mhatre
86246dc860
configuration-properties/ @ConfigurationProperties vs @Value on Spring Boot 4.1.1. The relaxed-binding matrix is generated by binding each spelling rather than transcribed, and re-checked against real processes -- the in-process probe was wrong twice before it was right. Records the three findings that came out of it: @Value does get relaxed resolution inside Spring Boot (Boot attaches ConfigurationPropertySources), the configuration processor silently stops generating metadata on JDK 23+ when declared as a plain dependency, and @Valid is not what makes nested constraints run. profiles-and-config/ Precedence, profiles, spring.config.import and config trees. /precedence reports every source holding a property in rank order with file and line, which turns "my profile file had no effect" into a two-line answer. Also pins the counterintuitive one: an imported file outranks the file that imported it. spring-aop/ Designators, proxy types, and aspects that do not fire. One advice per supported designator so the reference table is generated from real matches; all fourteen unsupported designators fed to the parser. Two corrections to the reference documentation: unsupported designators throw UnsupportedPointcutPrimitiveException (extends RuntimeException, not IllegalArgumentException), and spring-boot-starter-aop was renamed to spring-boot-starter-aspectj in Boot 4. 19 contract tests across the three modules, 15 captured transcripts, all regenerated by scripts/run-all.sh. Verified on Spring Boot 4.1.1, Spring Framework 7.0.9, JDK 25.0.4.1. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Gip4srpzMwjgoba6uEfbr5
85 lines
3.3 KiB
Markdown
85 lines
3.3 KiB
Markdown
[← Advice types](04-advice-types.md) · [Index](../README.md) · [Diagnosing →](06-diagnosing-a-silent-aspect.md)
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# 5. Six aspects that do not fire
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Sources: [`BrokenAspects`](../src/main/java/com/ankurm/aop/broken/BrokenAspects.java),
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[`SelfInvokingService`](../src/main/java/com/ankurm/aop/broken/SelfInvokingService.java),
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[`NewedUpService`](../src/main/java/com/ankurm/aop/broken/NewedUpService.java).
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Transcript: [`03-broken-gallery.txt`](output/03-broken-gallery.txt).
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None of these warn. None fail at startup. All of them look correct in review.
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## 1. `@Aspect` without `@Component`
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`@Aspect` is an AspectJ annotation. It tells Spring how to interpret a bean it already has; it
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does not create one. Without a stereotype or an `@Bean` method, the class is never instantiated
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and the pointcut is never registered.
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The most common cause, and the most invisible — from the container's point of view nothing was
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ever requested, so there is nothing to warn about.
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**Fix:** add `@Component`.
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## 2. A pointcut that matches nothing
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```java
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@Before("execution(* com.ankurm.aop.services.*.*(..))") // "services", plural
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```
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A package name matching no type is not an error; it is an empty match set. At runtime this is
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indistinguishable from an aspect that was never registered.
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**Fix:** assert on it. `AspectJExpressionPointcut#matches(Method, Class)` in a unit test is two
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lines and catches every typo permanently.
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## 3. A private method
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Neither proxy strategy can override a private method, so neither can intercept it. The
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annotation is legal and inert.
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**Fix:** make it at least package-private *and* call it from outside the object — visibility
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alone is not enough if the call is internal, which brings you to number 5.
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## 4. A final method
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CGLIB proxies by subclassing. A final method is inherited rather than overridden, so calls go
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straight to the original. A final *class* fails loudly; a final *method* is silent.
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Note `beanIsProxied: true` in the transcript. The bean is proxied. This one method is not.
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**Fix:** remove `final`, or proxy by interface.
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## 5. Self-invocation
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The expensive one, because the code looks right and the annotation is visible.
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```json
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"5-self-invocation": {
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"beanIsProxied": true,
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"innerAdvisedWhenCalledFromOuter": false,
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"innerAdvisedWhenCalledDirectly": true
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}
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```
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Same method, same advice. Called through the proxy it is advised; reached by `this.inner()`
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from another method of the same object it is not, because the proxy is not in that call path.
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This is the same mechanism that makes `@Transactional` and `@Cacheable` silently do nothing on
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internal calls. Learning it once here saves learning it three times.
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**Fixes, best first:**
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1. Move the method to another bean. This is almost always the right answer, and the resulting
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design is usually better anyway.
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2. Inject the bean into itself and call through that reference.
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3. `AopContext.currentProxy()` with `exposeProxy = true`. Works; couples your code to Spring
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AOP and makes the class aware it is proxied.
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## 6. An object created with `new`
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Spring AOP advises beans. An instance built by a factory, a helper or a test has no proxy and
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never will.
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**Fix:** get it from the container. If it genuinely must be constructed by hand and still
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advised, that is what AspectJ load-time weaving is for.
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