MethodHandles.Lookup.defineResource? (original) (raw)

Stephen Colebourne scolebourne at joda.org
Mon Aug 27 21:51:51 UTC 2018

The specific code was written in Java 8 world to create a ClassLoader containing the resource with a suitable parent (as a test case). The resource was accessed using ClassLoader.getResources() from a shared library. Under Java 9 I've had to change ClassLoader.getResources() to Class.getResource() in the shared library, which means that creating a new ClassLoader doesn't work for writing the test. (The relevant code is now untested, which is far from ideal). See the commit here: https://github.com/OpenGamma/Strata/commit/8f2d4d32630af2981d167418dab78c8e2fc98a64

The reason for this thread is a realisation that MethodHandles.Lookup.defineClass() allows a class to be pushed into an existing ClassLoader & Module, but I'm unaware of an equivalent for resources, and that seems like a gap, regardless of use case.

The reflection/setAccessible comment refers to articles like this: https://baptiste-wicht.com/posts/2010/05/tip-add-resources-dynamically-to-a-classloader.html

thanks Stephen

On Mon, 27 Aug 2018 at 07:53, Alan Bateman <Alan.Bateman at oracle.com> wrote:

On 14/08/2018 15:07, Stephen Colebourne wrote: > A new method MethodHandles.Lookup defineClass() was added recently. > But what about a defineResource? For adding a new resource to the > classpath (such as a .txt file). I just needed such a thing, and > though undoubtedly rare, all the recommended solutions use reflection > and setAccessible(). > It might be useful to expand on your use-case a bit more. It may be that you are really just looking to create a ClassLoader that can locate a resource that you generate at run-time. Also the mention of core reflection and setAccessible isn't clear as they aren't used with resources. -Alan

More information about the core-libs-dev mailing list