Java Classpath

[tripower]

Hello

another question
in the "old" / other Java NodeJS Bridge it was possible to set a whole path instead of single jars
is that here also possible and how?

old code => java.classpath.pushDir(localservicePath);

greetings
Klaus

[MarkusJx]

Uhm, no, that's currently not possible. A valid workaround would be to use glob:

import glob from 'glob';
import java from 'java-bridge';

java.classpath.append(glob.sync('*.jar', { cwd: 'your-dir-here' }));

But I'll add this to my list of things to do: #38

[tripower]

hello @MarkusJx

have seen that you solved an other bug
will you do #44 before creating a new version?

greetings Klaus

[MarkusJx]

Yes, I'll resolve #38 and #44 before creating a new release

[tripower]

ok
thx
good to know

greetings Klaus

[MarkusJx]

TL;DR: Spring boot uses its own class loader, you have to set the class path before jvm startup

So #38 is done, but I'll probably need some more time with the spring boot topic. My first guess was that I'm not correctly replacing the class loader, which may not be the case, as I wrote a test case for that, and it works:

node-java-bridge/test/ClassTest.test.ts

Line 143 in 72078a4

this.ext = Class.forName("dyn.external.Class1");

I'm also setting the context class loader for each thread correctly, so that's not an issue. Thus, my only guess is that spring boot is using its own class loader which does not work well with me creating my own little class loading adventure. And it also makes sense they're using their own class loader as spring boot supports hot reload to some extend and you'd probably need your own class loader for that to work.

Yeah, looking at your logs, spring boot definitely uses its own class loader, so the only option to get this to work would be adding the classes at application startup. I'll probably add a startup option allowing you to set your classpath more conveniently (as this is btw also a thing joeferner/java-bridge does). But you'll have to make sure to call ensureJvm before calling any other method from this package, as any method call probably itself will call ensureJvm and calling that method multiple times will cause all calls after the first one to be no-ops, as I can't safely shut down/restart the jvm. This is a limitation mostly given by rust or rather its core principles as destroying the jvm would cause undefined behaviour, which is a thing that anyone should try to avoid. Yeah.

[tripower]

thanks
tests after a new build is available will show more
hope that was the solution

hope also that the jvm will only one time at the startup initialized (startup of spring classes)
otherwise it would be performance overkill

so fingers crossed that all works 🤗🙏
and #44 will also soon fixed. thx

greetings Klaus