Version using gradle properties file

versionizer.gradle

def versionFile = project.file("version.properties")

Version version = Version.read(versionFile)
ext {
    versionizerVersionCode = version.code
    versionizerVersionName = version.name
}

task incrementVersionForRelease << {
    group = 'release'
    description = 'Loads the information about the last release and increases the version'
    Version.increment(versionFile)
}

class Version {
    private static final String KEY_CODE = 'VERSION_CODE'
    private static final String KEY_NAME = 'VERSION_NAME'
    private static final String VERSION_NAME_DATE_FORMAT = 'yyyy.MM.dd'

    int code
    String name

    static void increment(File versionFile) {
        read(versionFile).increment().store(versionFile)
    }

    static Version read(File versionFile) {
        Properties properties = new Properties()
        properties.load(versionFile.newDataInputStream())
        int versionCode = properties.getProperty(KEY_CODE) as int
        String versionName = properties.getProperty(KEY_NAME)
        return new Version(code: versionCode, name: versionName)
    }

    void store(File versionFile) {
        Properties properties = new Properties()
        properties.setProperty(KEY_CODE, "$code")
        properties.setProperty(KEY_NAME, name)
        properties.store(versionFile.newOutputStream(), null)
    }

    Version increment() {
        new Version(code: code + 1, name: new Date().format(VERSION_NAME_DATE_FORMAT))
    }

}