How to interrupt JoinPoint execution in AOP

Question

Is it possible to interrupt invoking the actual method from within the aspect execution? For example:

public class CheckPermissionAspect {
  
  @Around("@annotation(CheckPermission)")
  public Object methodLogging( ProceedingJoinPoint joinPoint) throws Throwable {
  
    // before method execution
    MethodSignature signature = (MethodSignature) joinPoint.getSignature();
    log.info("Enter ==> " + signature.getMethod().getName());
    
    if ( getPermission( principal.getName()) == false ) {

       // break the execution of actual method
       Object result = null; // ???
       log.info("Break ==> " + signature.getMethod().getName());
    } else {

       // invoke the actual method
       Object result = joinPoint.proceed();

       // after method execution
       log.debug("Result: " + result);
       log.info("Leave ==> " + signature.getMethod().getName());
    }


    
    return result;
  
  }
  
}

To set Object result = null; does not work. Thank you for any help.

Answer 1

From Spring Reference documentation : Around Advice

Within the body of the advice method, you must invoke proceed() on the ProceedingJoinPoint in order for the underlying method to run

If joinPoint.proceed() is removed from the code or an exception is thrown before joinPoint.proceed() statement or a return is issued before joinPoint.proceed() statement , the execution of the underlying method would get interrupted.

Update : to answer the comment

Spring AOP is proxy based. To understand this concept better , do read through : Understanding AOP proxies

An advice is placed between the calling method and the target. All calls to the target method gets intercepted and advised.

You could throw an exception upon validation ( Do note that the exception type thrown should match the exception type of the target method . Go through this Q&A).

The exception/return value from the advise would reach back the calling method .