Cleanest way in Gradle to get the path to a jar file in the gradle dependency cache

Question

I\'m using Gradle to help automate Hadoop tasks. When calling Hadoop, I need to be able to pass it the path to some jars that my code depends on so that Hadoop can send that de

Answer 1

I recently had this problem as well. If you are building a java app, the problem at hand is normally that want to get the group:module (groupId:artifactId) to path-to-jar mapping (i.e. the version is not a search criteria as in one app there is normally only one version of each specific jar).

In my gradle 5.1.1 (kotlin-based) gradle build I solved this problem with:

var spec2File: Map = emptyMap()
configurations.compileClasspath {
    val s2f: MutableMap = mutableMapOf()
    // https://discuss.gradle.org/t/map-dependency-instances-to-file-s-when-iterating-through-a-configuration/7158
    resolvedConfiguration.resolvedArtifacts.forEach({ ra: ResolvedArtifact ->
        s2f.put(ra.moduleVersion, ra.file)
    })
    spec2File = s2f.mapKeys({"${it.key.id.group}:${it.key.id.name}"})
    spec2File.keys.sorted().forEach({ it -> println(it.toString() + " -> " + spec2File.get(it))})
}

The output would be some like:

:jing -> /home/tpasch/scm/db-toolchain/submodules/jing-trang/build/jing.jar
:prince -> /home/tpasch/scm/db-toolchain/lib/prince-java/lib/prince.jar
com.github.jnr:jffi -> /home/tpasch/.gradle/caches/modules-2/files-2.1/com.github.jnr/jffi/1.2.18/fb54851e631ff91651762587bc3c61a407d328df/jffi-1.2.18-native.jar
com.github.jnr:jnr-constants -> /home/tpasch/.gradle/caches/modules-2/files-2.1/com.github.jnr/jnr-constants/0.9.12/cb3bcb39040951bc78a540a019573eaedfc8fb81/jnr-constants-0.9.12.jar
com.github.jnr:jnr-enxio -> /home/tpasch/.gradle/caches/modules-2/files-2.1/com.github.jnr/jnr-enxio/0.19/c7664aa74f424748b513619d71141a249fb74e3e/jnr-enxio-0.19.jar

After that, it is up to you to do something useful with this Map. In my case I add some --path-module options to my Java 11 build like this:

val patchModule = listOf(
        "--patch-module", "commons.logging=" +
        spec2File["org.slf4j:jcl-over-slf4j"].toString(),

        "--patch-module", "org.apache.commons.logging=" +
        spec2File["org.slf4j:jcl-over-slf4j"].toString()
)
patchModule.forEach({it -> println(it)})

tasks {
        withType {
            doFirst {
                options.compilerArgs.addAll(listOf(
                        "--release", "11",
                        "--module-path", classpath.asPath
                ) + patchModule)
                // println("Args for for ${name} are ${options.allCompilerArgs}")
            }
        }
}