task deleTask(type: Delete){
FileTree tree = fileTree(dir: bakPath)
tree.each {File file ->
if(!file.toString().contains(oldFileName)){
delete file
}
}
}
deleTask
task clearBacApkDir(type: Delete) { file( bakPath ).list().each{ f -> if(!f.contains(baseInfo)) { delete "${bakPath}/${f}" } } } clearBacApkDir
原文：http://www.cnblogs.com/androiddream/p/7880584.html