Alternatives to Java bytecode instrumentation

Question

I'm starting a project that will have to instrument java applications for coverage purposes (definition-usage of variables, etc). It has to add trace statements and some logic to the application and maybe remove statements.

I have searched for ways of instrument Java code and what I always find is about bytecode instrumentation.

My question is: It's the only way to instrument Java applications? There is any other way to do that? What are the advantages of bytecode instrumentation over the others?

I'll probably use the bytecode solution, but I want to know what are the problems with the other approaches (if any) to decide precisely.

Thanks!

Answer 1

The other method close to changing bytecode is using AOP (Aspect Oriented Programming). The main library is AspectJ which also mostly defines the area.

The third option that might be interesting (since you are just starting out with the program) is using Spring. It means you will have to learn a bit about IOC (inversion of control) but it basically means that instead of creating your objects yourself you let spring do it for you, and it has it advantages because when spring is incharge of the creation it can add all sorts of things in the creation process without you having to really declare it all yourself in aspectj.

In terms of complexity I would probably rate it:

• spring (easiest)
• aspectj
• bytecode instrumentation (hardest)

but it's exactly the other way around when talking about capabilities (power). for example doing something like substracting code is only possible using the last one (I think)