这是一个不使用插件的版本，更像是Groovy版本。

import org.gradle.jvm.tasks.Jar

val fatJar = task("fatJar", type = Jar::class) {
    baseName = "${project.name}-fat"
    manifest {
        attributes["Implementation-Title"] = "Gradle Jar File Example"
        attributes["Implementation-Version"] = version
        attributes["Main-Class"] = "com.mkyong.DateUtils"
    }
    from(configurations.runtime.map({ if (it.isDirectory) it else zipTree(it) }))
    with(tasks["jar"] as CopySpec)
}

tasks {
    "build" {
        dependsOn(fatJar)
    }
}

Also explained here

一些评论者指出，这在更新的Gradle版本中不再起作用。 使用Gradle 5.4.1测试的更新：

import org.gradle.jvm.tasks.Jar

val fatJar = task("fatJar", type = Jar::class) {
    baseName = "${project.name}-fat"
    manifest {
        attributes["Implementation-Title"] = "Gradle Jar File Example"
        attributes["Implementation-Version"] = version
        attributes["Main-Class"] = "com.mkyong.DateUtils"
    }
    from(configurations.runtimeClasspath.get().map({ if (it.isDirectory) it else zipTree(it) }))
    with(tasks.jar.get() as CopySpec)
}

tasks {
    "build" {
        dependsOn(fatJar)
    }
}

请注意configurations.runtimeClasspath.get()和with(tasks.jar.get() as CopySpec)中的差异。