Spring Boot Aspect-Oriented Programming Questions and Answers

Question 1

In a Spring Boot application, which AOP advice type provides the most control over a method's execution, allowing you to modify arguments, control whether the method proceeds, and alter the return value?

Accepted Answer

@Around

Answer

@Before

Answer

@AfterReturning

Answer

@AfterThrowing

Question 2

A developer needs to apply logging to all public methods within any class in the `com.example.service` package. Which of the following is the correct AspectJ pointcut expression for this scenario?

Accepted Answer

execution(public * com.example.service.*.*(..))

Answer

execution(* com.example.service.*.*(..))

Answer

within(com.example.service.*)

Answer

target(com.example.service.*)

Question 3

What is the fundamental difference between a Join Point and a Pointcut in Spring AOP?

Accepted Answer

A Join Point is a potential point in the code where advice can be applied (like a method execution), while a Pointcut is an expression that selects one or more Join Points.

Answer

A Join Point is the execution of advice, while a Pointcut is the method being advised.

Answer

A Pointcut is a specific occurrence of a Join Point during the program's execution.

Answer

They are interchangeable terms for the same concept in AOP.

Question 4

A developer has an aspect with `@Around` advice that measures the execution time of a service method. If the developer forgets to call `ProceedingJoinPoint.proceed()` inside the advice, what will be the outcome?

Accepted Answer

The advice will execute, but the target service method will not.

Answer

The application will throw a runtime exception.

Answer

The target service method will execute, but the advice's post-processing logic will be skipped.

Answer

The AOP proxy will fail to be created, causing a startup error.

Question 5

Under which circumstance will Spring AOP default to using a CGLIB proxy instead of a JDK dynamic proxy?

Accepted Answer

When the target bean to be proxied does not implement any interfaces.

Answer

When the target bean is declared with a `@Component` annotation.

Answer

When the application is configured with `spring.aop.proxy-target-class=false`.

Answer

When the target bean implements only one interface.

Question 6

How do you enable AspectJ support in a modern Spring Boot application that uses Java configuration?

Accepted Answer

It is enabled by default if `spring-boot-starter-aop` is on the classpath; no explicit annotation is needed.

Answer

By adding the `<aop:aspectj-autoproxy/>` element to an XML configuration file.

Answer

By annotating a configuration class with `@EnableAspectJAutoProxy`.

Answer

By creating a bean of type `AspectJWeaver` in the application context.