scala list available resources. / published by https://github.com/dacr/code-examples-manager #a8328208-2218-4c90-8530-e3143e0ce4fa/3bba9f136d0fc8a1faef9ddaa8f481270517e211

scala-list-resources.sc

// summary : scala list available resources.
// keywords : scala, classloader, resources, @testable
// publish : gist
// authors : David Crosson
// license : Apache License Version 2.0 (https://www.apache.org/licenses/LICENSE-2.0.txt)
// id : a8328208-2218-4c90-8530-e3143e0ce4fa
// created-on : 2020-05-31T19:54:52Z
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.4.2"
//> using dep "org.scalatest::scalatest:3.2.10"
//> using dep "fr.janalyse::drools-scripting:1.0.16"
// ---------------------

import org.scalatest.flatspec._, org.scalatest.matchers._

import java.io.File, java.net.{URL,URLDecoder}, java.util.jar.JarFile
import scala.jdk.CollectionConverters._

def resourcesList(from: String): List[String] = {
  val goodFrom =
    from
      .trim
      .replaceAll("/{2,}", "/")
      .replaceAll("/$","")
      .replaceAll("^/","") + "/"
  def listContent(url:URL):List[String] = {
    url.getProtocol match {
      case "file" => new File(url.getPath).list().toList
      case "jar" =>
        val jarPath = url.getPath().substring(5, url.getPath().indexOf("!"))
        val jar = new JarFile(URLDecoder.decode(jarPath, "UTF-8"))
        val entries = jar.entries().asScala
        entries
          .filter(entry => entry.getName.startsWith(goodFrom))
          .flatMap(_.getName.drop(goodFrom.size).split("/").headOption)
          .toList
    }
  }
  val cl = Thread.currentThread().getContextClassLoader
  cl.getResources(goodFrom)
    .asScala
    .toList
    .flatMap(listContent)
    .filter(_.size>0)
    .distinct
}

object ResourcesListTest extends AnyFlatSpec with should.Matchers {
  override def suiteName: String = "ResourcesListTest"
  "resourcesList" should "list accessible resources" in {
    val r = resourcesList("META-INF")
    info("Discovered (distinct): "+r.sorted.mkString(", "))
    r.size shouldBe > (2)
    r should contain allElementsOf List( "services", "maven", "kie.conf", "LICENSE")
  }
  it should "not list anything when file resources" in {
    val r = resourcesList("META-INF/MANIFEST.MF")
    r.size shouldBe 0

  }
}


ResourcesListTest.execute()