Should ClassLoader::getResouces return the same resource twice?

[Thiago Henrique Hupner]

Looks like the ModuleLayer.defineModules is the thing I needed.
With it, I can use my current classloader to load all the modules
and it can find the classes from both module and unnamed module.

However, I'm having some trouble with the ServiceLoader now,
In the configuration, I've called resourceAndBind, but I'm getting
"Provider foo.bar not found"

There is some trick to get a class from an upper layer to bind to the
a class in the boot layer?

Thanks!

Em seg., 4 de jan. de 2021 às 09:41, Johannes Spangenberg <
johannes.spangenberg at hotmail.de> escreveu:

> The bidirectional delegation is an important point. Beside that, you
> also mentioned that your custom class loader stores additional information.
>
> > Unfortunately, I cannot only remove the jars from my classloader and
> > delegate
> > to the classloader provided by the ModuleLayer because we use a custom
> > classloader,
> > and have some important information stored in it, so by removing the
> > jars from the classloader
> > all applications would stop working.
>
> If you really need this information as part of the class loader, I fear
> you need to create custom class loaders for your modules together with
> ModuleLayer.defineModules [1] instead of
> ModuleLayer.defineModulesWithOneLoader. The class loader for
> ModuleLayer.defineModulesWithOneLoader is not public. I guess you would
> need to reimplement it. Maybe you can find other locations to store the
> information.
>
> [1]
>
> https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/lang/ModuleLayer.html#defineModules(java.lang.module.Configuration,java.util.List,java.util.function.Function)
>
> Am 04.01.2021 um 12:38 schrieb Thiago Henrique Hupner:
> > Yes, that's exactly it. Sorry for all the noise in the previous emails.
> >
> > I'm not using a URLClassLoader in my application, I've only used it
> > as an example because it is very easy to override to return a specific
> > value (and not have to implement all the other methods).
> >
> > So, I guess I will need to have a look at the application classloader
> > and update my current classloader to be able to do the bidirectional
> > delegation. Do you have any recommendations about where to look?
> >
> > Thanks!
> >
> > Em seg., 4 de jan. de 2021 às 05:48, Alan Bateman <
> Alan.Bateman at oracle.com>
> > escreveu:
> >
> >> On 03/01/2021 13:10, Thiago Henrique Hupner wrote:
> >>> :
> >>>
> >>> I hope made it a little more clear. By now it is clear that it is
> loading
> >>> the same
> >>> resource twice because the same jar is in the classloader and in the
> >> module
> >>> layer
> >>> classloader.
> >> If I read your mail correctly you've got a class path today and you want
> >> to "move" the well behaved components to a module path, leaving the
> >> remaining the components that can't work as automatic modules on the
> >> class path. It's equivalent to specifying both a module path and class
> >> path to the java command line launcher. You also mention that you have
> >> to use a custom class loader. If that class loader were updated to
> >> support modules and load classes into its unnamed module then you should
> >> be able to get this to work. This is very advanced territory and would
> >> be approximately equivalent to the application class loader in the JDK
> >> where it supports both modules and the class path. I don't think your
> >> current approach of using a URLClassLoader as a parent will work as it
> >> doesn't support the bidirectional delegation that would be need to get
> >> this to work.
> >>
> >> -Alan.
> >>
>