5.1 SP8 Custom ClassLoader ClassFormatError messages

Question

We use a custom ClassLoader that unscrambles classfiles not understood by its parent.
When the Weblogic parent ClassLoader attempts discovers it can't decipher the
file, it writes a ClassFormatError message and stack trace to the console (though
not to the log) before delegating to its child (our code) which proceeds to load
the class with no trouble. The result is that our product runs fine, but appears
to be full of unloadable classes. How can we get the Weblogic ClassLoader to suppress
these misleading error messages? (IMHO, it shouldn't report errors until and unless
both it and its child have failed, but given that it does, is there some way to
make it shut up?)

Answer 1

You can use class preprocessor in WebLogic for that sort of thing (products
like Wily and Tangosol use this feature to instrument or customize classes when
they are loaded by WebLogic classloaders) without adding your own classloaders,
for example, in 6.1:
public class ExamplePreprocessor implements weblogic.utils.classloaders.ClassPreProcessor {
public void initialize(java.util.Hashtable ht) {}
public byte[] preProcess(String classname, byte[] classbytes) {
     ... unscramble or do whatever is that you do with classbytes ...
return classbytes;
and add this to the WebLogic command line :
-Dweblogic.classloader.preprocessor=preprocessorclassname
Jonathan Shultis <[email protected]> wrote:
We use a custom ClassLoader that unscrambles classfiles not understood by its parent.
When the Weblogic parent ClassLoader attempts discovers it can't decipher the
file, it writes a ClassFormatError message and stack trace to the console (though
not to the log) before delegating to its child (our code) which proceeds to load
the class with no trouble. The result is that our product runs fine, but appears
to be full of unloadable classes. How can we get the Weblogic ClassLoader to suppress
these misleading error messages? (IMHO, it shouldn't report errors until and unless
both it and its child have failed, but given that it does, is there some way to
make it shut up?)--
Dimitri