Re: get the class object in the byte-code and more....

Often times questions like, "How i do this?" can be most easily answered by 
BCELifier, a tool bundled with the distribution that given a java class, 
writes a BCEL program to generate that class.

----- Original Message ----- 
From: "Andrea" <[email protected]>
To: <[email protected]>
Sent: Wednesday, July 05, 2006 5:30 PM
Subject: get the class object in the byte-code and more....


> Hi to everyone.
> I'm using BCEL from some days for my thesis so I've still a lot of things 
> to
> learn about bytecode instrumentation. I want to ask you two things:
> 1) How can I create in the bytecode I'm producing, an instruction 
> corresponding
> to the statement Classname.class? I imagine that if I use
> Class.forName(classname) would be ok but it doesn't work for primitive 
> type.
>
> 2) There some way to bring an object instance I have in the method wich 
> does the
> instrumentation into the instrumented method?
> I try to explain it better:
> I have a method with this signature
>
> public static void instrument(ClassGen cgen, Method mth, BAnnotation an
>
> In it I want to modify the bytecode of Method mth to insert a call to an
> external method and I want to pass to this second method the BAnnotation 
> object
> (that is more or less a java annotation but don't think to much about it).
> Since now I've thought to the following solutions:
> - instead of passing the annotation to the external method, I could 
> extract the
> meta-data from the annotation, insert them in the instrumented method as 
> local
> variables (I wouldn't have any problem cuase the metadata will be String 
> or
> primitive) and call a new external method who takes the data in that form. 
> I
> think it could work but with complex annotations will be an hard work to 
> create
> all the needed bytecode and specially it will be hard in future to modify 
> it
> - I could insert in the created bytecode the needed calls to retrieve via
> reflection the annotation and then I could pass the object obtained to the
> external method. Not so complicated as the first solution but everytime I 
> have
> to search for the right annotation.
> - I'm not sure it could be done with annotation (well I'm not even sure it 
> can
> be done with other object) but I could serialize my BAnnotation object 
> pass to
> the external method the info to the deserialize it
>
> I would be glad if someone have some suggestions or opinions on what I've
> written above. Unfortunately my english is not so good, and I'm not sure 
> that
> what I've written is clear...
> Thanks for reading
> bye!
>
> Andrea^^
>
>
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