How to automatically log the entry/exit of methods in Java?

Question

Right now I am using java.util.logging to log the entry and exit points of each method in my Java project. This is very useful to me when debugging.

I have this piece of code at the beginning of each method and a similar one at the end:

if (logger.isLoggable(Level.FINER)) {
    logger.entering(this.getClass().getName(), "methodName");
}

Where "methodName" is the the name of the method (hardcoded).

So I was wondering if there is a way to do this automatically without having to include this code in every method.

Answer 1

I suggest the use of Aspect Oriented Programming.

For example, using the AspectJ compiler (which can be integrated to Eclipse, Emacs and others IDEs), you can create a piece of code like this one:

aspect AspectExample {
    before() : execution(* Point.*(..))
    {
         logger.entering(thisJoinPointStaticPart.getSignature().getName(), thisJoinPointStaticPart.getSignature().getDeclaringType()   );

    }

    after() : execution(* Point.*(..))
    {
         logger.exiting(thisJoinPointStaticPart.getSignature().getName() , thisJoinPointStaticPart.getSignature().getDeclaringType()  );

    }
}

This aspect adds a logging code after and before the execution of all methods in the class "Point".

Answer 2

You should look at Aspect oriented programming. I would suggest Spring AOP or AspectJ as something that you should look at.

Also, here's a quick tutorial to help you get started with Logging with Spring AOP

Answer 3

As already suggested, use AOP with @Loggable annotation from jcabi-aspects (I'm a developer):

@Loggable(Loggable.DEBUG)
public String load(URL url) {
  return url.openConnection().getContent();
}

The library also contains an AOP aspect which understands these annotations and automatically logs method calls, their arguments, and execution time through SLF4J.

Also, check this blog post that explains the details: http://www.yegor256.com/2014/06/01/aop-aspectj-java-method-logging.html

Answer 4

Have you tried to look at slf4j? It has LocationAwareLogger that can collect automatically method name.

Answer 5

You should look at Aspect Oriented Programming, particularly the around() joinpoint that would be useful to log the entry and exit of methods that you would like to qualify in the definition.