Gradle Goodness: Unpacking an Archive

To create an archive with Gradle is easy. We have several tasks like Zip, Tar, Jar, War and Ear to create a new archive. But there is no UnZip or UnTar to unpack an archive in Gradle. To unpack an archive we must use the Copy task and copy the contents of the archive to a specified destination directory. In Gradle we can use the zipTree() method to access the contents of an archive. So in our copy definition the source is the contents of the archive we access with the zipTree() method.

In the following build file we see a simple task to unzip a ZIP file with the name dist.zip in the directory src/dists. We unpack the contents to the directory build/unpacked/dist:

task unzip(type: Copy) {
    def zipFile = file('src/dists/dist.zip')
    def outputDir = file("${buildDir}/unpacked/dist")

    from zipTree(zipFile)
    into outputDir
}

The good thing is that tasks of type Copy automatically support Gradle's incremental build support. This means that if the task has been executed once and the dist.zip file and output in the directory build/unpacked/dist has not change the task is up-to-date and isn't executed.

We get the following output if we run the task twice:

$ gradle unzip
:unzip
 
BUILD SUCCESSFUL
 
Total time: 2.867 secs
unzip mrhaki$ gradle unzip
:unzip UP-TO-DATE
 
BUILD SUCCESSFUL
 
Total time: 2.606 secs
$