Re: [aspectj-dev] Can I intercept before a class is load time weaved

[Martin Lippert <lippert@xxxxxxx>]

Hi Choudary,

> a) It is about the temporary classloader I need so that I can load the
> class and use ObjectStreamClass.lookup(clazz).getSerialVersionUID() to
> find the SUID that Java would generate. For this I need to know the
> application classpath. I am assuming (and it is working in a client's
> Swing application) that the classloader instance passed to the
> Aj.preProcess(...) is URLClassLoader and I am calling getURLs() to get
> all the paths to search. I am passing null as the parent of my
> temporary classloader as the class should not be loaded before passing
> to the AspectJ weaver. Is this going to break in a J2EE environment?
> Is there a better way to find the classpaths to search? I couldn't
> find any temporary classloader implementation in your samples.

I think of two problems here:

- the creation of a temp classloader to figure out the SUID of the class 
that the JVM would generate sounds like a lot of overhead at runtime. 
Are you sure this performs well enough for your setting?

- The assumption of an URL classloader is fragile, I think. In an OSGi 
environment this wouldn't work and I assume this could break in a JEE 
environment as well.

Wouldn't it be possible to operate on the BCEL level only and calculate 
the SUID from that yourself without using the method of 
ObjectStreamClass? This would also solve your dependency on the 
URLClassLoader.

Just my 2 cents,
-Martin