Gradle task to load files from Jar

Question

I use vendor library to generate Java sources from an Xml. This source xml imports other xml which exists in some jar file. I know the coordinates of this Jar file. The vendor library is a blackbox to me but I know that it uses ThreadContextClassLoader to load the imports from a jar. However, it fails because it cannot find the imported xmls from the classpath/jars.

What is the gradle way of accomplishing this?

// body of gradle task
@TaskInput
void execute(IncrementalTaskInputs inputs) {
   inputs.outOfDate { changes ->
       // CodeGenerator is the vendor library
       CodeGenerator generator = new CodeGenerator();
       // call some setter methods to set the inputs.
       //
       generators.setXml(file("<path/to/the-file"))
       generator.generate();
   } 
}

maybe you can paste how you currently invoke the vendor library from gradle. Then maybe it's just a matter of adding the jar to the classpath of that command. — tkruse, Nov 30 '17 at 06:25

score 1 · Answer 1 · answered Nov 30 '17 at 16:08

Does the CodeGenerator have a setClassloader(Classloader) method? You could likely use a Configuration and a URLClassloader. Eg:

configurations {
   codeGenerator
}
dependencies {
   codeGenerator 'foo:bar:1.0'
   codeGenerator 'baz:biff:2.0'
}
task generateCode {
    inputs.files configurations.codeGenerator
    outputs.dir "$buildDir/codeGenerator"
    doLast {
        URL[] urls = configurations.codeGenerator.files.collect { it.toUri().toUrl() }
        Classloader cl = new URLClassLoader(urls, null)
        CodeGenerator generator = new CodeGenerator()
        generator.setClassLoader(cl)
        ...
        generator.generateTo("$buildDir/codeGenerator")
    }
}

See a similar concept here

Unfortunately, there is no setter method to set URLClassLoader. — chauhraj, Nov 30 '17 at 17:13

score 1 · Accepted Answer · answered Dec 01 '17 at 10:03

1

From my other answer we have ascertained that there's no option to set the classloader for the CodeGenerator. So, the only option is to have the jar with the xml files loaded by the same classloader as the CodeGenerator`.

Option 1: Add the jar to the buildscript classpath in a buildscript { ... } block

buildscript {
    dependencies {
         classpath 'com.group:jar-with-xmls:1.0'
    }
}

Option 2: Add the jar to the buildscript classpath via buildSrc/build.gradle

dependencies {
    compile 'com.vendor:code-generator:1.0'
    runtime 'com.group:jar-with-xmls:1.0'
}

answered Dec 01 '17 at 10:03

lance-java

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Thanks, Option 1 worked for me. I am curious to know in what way Option 2 is different from Option 1. – chauhraj Dec 01 '17 at 20:24
You would use option 2 if you wanted to compile extra tasks etc in `buildSrc/src/main/java` – lance-java Dec 01 '17 at 22:15

score 0 · Answer 3 · answered Nov 30 '17 at 06:02

0

jar files are zip archives. You can open them as zipfiles using java.util.zip classes. In gradle, you might want to use ziptree to extract, as explained here: http://mrhaki.blogspot.jp/2012/06/gradle-goodness-unpacking-archive.html

answered Nov 30 '17 at 06:02

tkruse

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I know how to get a ZipEntry. Problem is that I provide the name of xml to the library and thats it. The library itself parses the Xml and figures what other Xml to imports. I do not have mechanisms to get the names of the file to be loaded. – chauhraj Nov 30 '17 at 06:21

Gradle task to load files from Jar

3 Answers3