I have converted a simple Spring project made with pure aop namespace xml coding to the same project but using annotations this time.
I've noticed that now the before-part of the around advice comes out before the before advice, which is the exact opposite behavior of the project's result when I was using aop namespace xml coding.
Is it the default behavior of the annotation style?
See Advice ordering:
When two pieces of advice defined in different aspects both need to run at the same join point, unless you specify otherwise the order of execution is undefined. You can control the order of execution by specifying precedence. This is done in the normal Spring way by either implementing the org.springframework.core.Ordered interface in the aspect class or annotating it with the Order annotation. Given two aspects, the aspect returning the lower value from Ordered.getValue() (or the annotation value) has the higher precedence.
Since the ordering is undefined, it could possibly vary even between multiple executions (having the same xml config).
Related
I am using Spring AOP to log the DB execution time, but it is applying to the entire method execution time.
#Target(ElementType.METHOD)
#Retention(RetentionPolicy.RUNTIME)
public #interface TrackExecutionTime {
}
Is there any possibility that we can use this #TrackExecutionTime not in the method level but inside a method just above some statement like below -
#TrackExecutionTime
List<Release> releaseList = releaseRepo.findByProductName(productName.toUpperCase());
that way I can able to get only the DB execution time not only the entire method execution time, as my method contains other business logic too which also including if we use the AOP annotation at the method level.
Your question is not AOP-specific, because annotations are a Java language feature. The answer is: Annotations on arbitrary lines of code are not part of the Java language concept, which for you means you also cannot use them for AOP purposes. This is simply a Java limitation. Neither Spring AOP nor native AspectJ can support a feature which does not exist in Java to begin with.
Friendly suggestion: Please learn more about Java first, then get acquainted with some basic software design and clean code principles. Finally, you shall be able to achieve what you want, albeit in a different way from what you just dreamed up here.
Spring AOP default configuration uses proxies to execute the aspect hence only methods can be annotated.
A bit of a detour on the proxies. A proxy wraps a target method so when you call a method elsewhere Spring makes sure to invoke the method on the proxy and that invocation then contains the aspect code which gets executed before, after, around the call itself (depending on the aspect). There can be several proxies wrapping a single class.
Then an option is to add your aspect annotation to the repository method.
If we need to track the execution time only for subset of calls to the method (which sounds a bit strange a requirement) then we can add a wrapper method - say make a Spring-managed Metrics class with a said time tracking method that accepts a lambda and is annotated with the #TrackExecutionTime. The original call would then be something like
metrics.executeTimed(() -> releaseRepo.findByProductName(productName.toUpperCase()));
Suppose multiple aspects are in application and be applied on a certain method. The annotation #order or Ordered interface can specify their precedence.
But if the values of #Order are same, how to determine the apply order?
When two pieces of advice defined in different aspects both need to run at the same join point, unless you specify otherwise the order of execution is undefined. You can control the order of execution by specifying precedence. This is done in the normal Spring way by either implementing the org.springframework.core.Ordered interface in the aspect class or annotating it with the Order annotation. Given two aspects, the aspect returning the lower value from Ordered.getValue() (or the annotation value) has the higher precedence.
It cannot be controlled, reference from doc 6.2.4.7
Our project has multiple FailureAnalyzers. Currently, a less informative one is kicking in before a more informative one.
Looking through the Spring Boot code, it looks like there's a way to set some sort of order but the code is fairly generic so it's difficult to see exactly how that should be done. What are the annotations to use to configure this order?
The analyzers are sorted using Spring Frameworkâs AnnotationAwareOrderComparator. That means that they can be ordered absolutely by annotating the class with#Order or by implementing Ordered. Relative ordering is not supported.
So far, in our project, we have got our beans having the references set through setter injections; recently, couple of people have started to use #Autowired annotation to set the references on their beans; is it a good to mix annotations and xml configurations for context?
There is no problem using the two together but better to choose one for consistency sake. It would be easier for all the developers to understand and maintain the code.
My preference is annotations as I like things defined at one place.
Mixing annotations and XML definitions works pretty well to reduce amount of code in XML file.
Certainly you can have both coexisting; XML definitions will always override any annotations in Java code without causing a trouble.
Is it good or bad?? I think it's just a way to balance size of an XML file. I find very useful to define my beans in a simple way in XML and then just use #Autowire annotation including #Required to ensure bean has been properly injected before been used.
I'm studying both of these approaches to include transactions in my Spring application. As for now, I prefer using annotations, as opposed to the tx namespace. The reason is that it sort of clears up the XML/complexity. But this is just my opinion.
I have not had a chance to see what current Spring practitioners use for transactions. Which one is now the preferred approach, and why?
In other words, what are the pros and cons of each approach that ultimately justify the use of one over the other?
<tx:advice> / <tx:attributes> / <tx:method>
Pros
No Spring-dependencies in your code
Very flexible, e.g. make all methods with get prefix transactional but read-only
Easily applying transaction demarcation into wide range of beans
Cons
cumbersome and hard to maintain XML
more XML
...even more XML
#Transactional and <tx:annotation-driven/>
Pros
Dead-simple, just add annotation over class or method
One line of XML (or even none with #EnableTransactionManagement) and it just works
Cons
Spring dependency in your code
Not possible to apply more general rules, like: all classes within a package that end with Dao
I would prefer to use annotations for marking transactions, not because of the ease of configuration or because of concerns about purity of coupling to Spring, but rather because it is typically the case that the code inside the method cannot work correctly without a transaction in place: the annotation is indicating something functional about the implementation as opposed to the way in which the code is managed (which would belong to the Spring configuration file).