How to read a file in src/main/resources in grails - grails

Question

This has been asked before, and I have tried each proposed solution, but all fail.
I have put a javascript file (hl.js) in myapp/src/main/resources
I have tried to read it with the following code taken from the "solutions":
1 - getRsourcesAsStream. returns null inputstream.
InputStream is = this.class.classLoader.getResourceAsStream("hl.js")
2 - getResource - returns null
File myFile = grailsApplication.mainContext.getResource("hl.js").file
3 - getResourceAsStream with classloader - returns null.
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream is = classLoader.getResourceAsStream("hl.js");
Interestingly, if I do the following:
String fileNameAndPath = this.class.classLoader.getResource("hl.js").getFile()
System.out.println(fileNameAndPath);
File file = new File(fileNameAndPath)
InputStream is = file.newInputStream();
This prints out:
/Users/me/dev/grails_projects/myapp/src/main/resources/hl.js
But "is" is always null.
I an trying to get an input stream so I can evaluate the javascript via nashorn:
ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
engine.eval(is)
Grails 3.3.8
Any ideas?

Answer 1

Get the resource and open a stream on it.
def resource = this.class.classLoader.getResource('conf.json')
def path = resource.file // absolute file path
return resource.openStream() // input stream for the file
Source: https://www.damirscorner.com/blog/posts/20160313-AccessingApplicationFilesFromCodeInGrails.html

Answer 2

Well, I dont know why the solutions 1, 2 and 3 do not work, but I found a more long winded way which does work. The main issue is that there are lots of different implementations of eval(), and netbeans "go to declaration" has never worked (presumably some configuration issue in netbeans).
It turns out that the eval() version i happen to be using is expecting a Reader, where as the default documentation shows it needs in InputStream. Also, reader is not the same as InputStreamReader.
This is the solution I found:
import javax.script.ScriptEngine
import javax.script.ScriptEngineManager
import org.grails.core.io.ResourceLocator
ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
String fileNameAndPath = this.class.classLoader.getResource("hl.js").getFile()
System.out.println(fileNameAndPath);
File file = new File(fileNameAndPath)
System.out.println("exists: " + file.exists())
Reader reader = file.newReader();
engine.eval(reader)