Customer ClassLoader: keeping JWS from loading jars

Question

I really like the ability of JWS to be able to download jars required for my application to run, but there are several jars that I need the ability to load up via a custom ClassLoader. But because JWS includes all of these jars in the classpath upon application start, the system class loader will take the first class it can find. Because I need to load classes from these jars based upon something a user selects, I need to have control over the codesource for these classes. Does anyone have any ideas on how to tackle this problem? Not include the jars in the jnlp and then download if not cached locally, if that's the case what's the best way to do that? Include in jnlp and be able to load with custom classloader(I dont think this will work)? Any ideas on this would greatly be appreciated.

Answer 1

Easiest solution to your problem and still being able to use the update mechanism of JWS is to include your JAR-file in another JAR-file that JWS loads, and then write up your own classloader, which tries to fetch your JAR-file from the downloaded JAR-file (if JWS already downloaded it, otherwise JWS will download it).
The contents of the jws-stub.jar would be something
of the following ;).
jws-stub.jar
--> myjar1.jar
--> myjar2.jar
org.myjar.MyJarClassloader
Then based on your user selecting something you
can decide which JAR-file you want to load, and thus
which class.
Hope this helped,
Manfred.