how to export a executable jar in gradle, and this jar can run as it include reference libraries

Question

how to export a executable jar in gradle, and this jar can run as it include reference libraries.

build.gradle

apply plugin: \'java\'

manifest.mainA         


        

Answer 1

All of these answers are either wrong or out of date.

The OP is asking for what is known as a "fat jar". That is an exectuable jar which contains all the dependencies so that it requires no outside dependencies in order to run (except for a JRE of course!).

The answer at the time of writing is the Gradle Shadow Jar plugin, explained pretty clearly at Shadow Plugin User Guide & Examples.

I struggled a bit. But this works:

put all these lines somewhere in your build.gradle file (I put them near the top) :

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.4' 
    }
}
apply plugin: 'com.github.johnrengelman.shadow'
shadowJar {
    baseName = 'shadow'
    classifier = null
    version = null
}
jar {
    manifest {
        attributes 'Class-Path': '/libs/a.jar'
        attributes 'Main-Class': 'core.MyClassContainingMainMethod'
    }
}

PS don't worry about any other "repositories", "dependency" or "plugin" lines elsewhere in your build file, and do leave the lines thus inside this "buildscript" block (I haven't a clue why you need to do that).

PPS the Shadow Plugin User Guide & Examples is well-written but doesn't tell you to include the line

attributes 'Main-Class': 'core.MyClassContainingMainMethod'

where I've put it above. Perhaps because the author assumes you are less clueless than I am, and you probably are. I haven't a clue why we are told to put a strange "Class-Path" attribute like that in, but if it ain't broke don't fix it.

When you then go

> gradle shadowjar

Gradle will hopefully build a fat executable jar under /build/libs (default name "shadow.jar") which you can run by doing this:

> java -jar shadow.jar