Reputation: 376

How to log/trace any method call of object in java

I need some thing like a Python decorator. I need to store some information, specifically the method called, its start time, its end time, and its arguments. I cannot import anything outside of Java 1.5 libraries. Is there some thing like what is available in Python?

Upvotes: 4

Answers (6)

yegor256

Reputation: 105053

@Loggable annotation and an AspectJ aspect from jcabi-aspects may help you. Annotate all your methods and every time they are being called SLF4J will receive log messages:

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

In the next versions of jcabi-aspects a full logging of a class will be implemented: https://github.com/yegor256/jcabi/issues/129

Upvotes: 0

stryba

Reputation: 2027

You might get away with a Java Proxy class if you can rely on interface methods only.

Upvotes: 0

umbr

Reputation: 440

Good tracing tool for Java is BTrace.

Upvotes: 6

fdreger

Reputation: 12495

No, Python decorators do not let you monitor all the code without changing anything. You still have to put your decorator everywhere (and - essentially - wrap each of your functions into a function that does the counting).

I am not sure if I understand your requirements (you do not say if you need the code for production or testing; also, the requirement "not to import anything" is bizarre: are all your classes in the default package? are you allowed to use an IDE and a compiler?), but I think the simplest way would be to use Javassist (the second link kindly provided by cschooley is a perfect introduction), but do not use the agent: instead use CtClass#write() to instrument class files and save them to disk (possibly in a custom ant task). This way the final build will not need any special set-up.

Upvotes: 0