utils.gradle

ext.getVersionCode = {
    majorVersion, minorVersion, patchVersion, buildVersion ->
        return majorVersion * 10000000 + minorVersion * 100000 + patchVersion * 1000 + buildVersion
}

ext.getVersionName = {
    majorVersion, minorVersion, patchVersion ->
        return "${majorVersion}.${minorVersion}.${patchVersion}"
}

ext.renameArtifact = {
    name, variant ->
        variant.outputs.all {
            output ->
                def date = new Date().format("yyyyMMdd")
                outputFileName = "${name}-${project.name}-${variant.versionName}-${variant.versionCode}-${date}-${variant.name}.apk"
        }
}