Example
import groovy.json.JsonSlurper;
def jsonSlurper = new JsonSlurper()
File fl = new File('/path/to/fils.json')
// parse(File file) method is available since 2.2.0
def obj = jsonSlurper.parse(fl)
// for versions < 2.2.0 it's possible to use
def old = jsonSlurper.parse(fl.text)
