JGitDiff.kt

fun main(args: Array<String>) {
    val repository: Repository = FileRepositoryBuilder().setGitDir(
            File("C:\\Users\\Crulio\\IdeaProjects\\test").resolve(".git")
    ).build()
    
    Git(repository).use { git ->
        DiffFormatter(System.out).apply {
            setRepository(repository)
            scan(
                    prepareTreeParser( git.getRepository(),  Constants.HEAD ),
                    FileTreeIterator(repository)
            ).forEach {
                format(it)
            }

        }
    }
}

fun prepareTreeParser(repository: Repository, ref: String): AbstractTreeIterator {
    val head = repository.exactRef(ref)
    RevWalk(repository).use { walk ->
        val commit = walk.parseCommit(head.objectId)
        val tree: RevTree = walk.parseTree(commit.tree.id)
        val treeParser = CanonicalTreeParser()
        repository.newObjectReader().use { reader -> treeParser.reset(reader, tree.id) }
        walk.dispose()
        return treeParser
    }
}