import java.util.regex.Pattern

def doExtractStringFromManifest(name) {
    def manifestFile = file("AndroidManifest.xml")
    if (!manifestFile.exists()) {
      manifestFile = file("src/main/AndroidManifest.xml")
    }
    def pattern = Pattern.compile(name + "=\"(.*?)\"")
    def matcher = pattern.matcher(manifestFile.getText())
    matcher.find()
    return matcher.group(1)
}

android {
    defaultConfig {
        applicationId = doExtractStringFromManifest("package")
    }
}