自動增量方法定義

 /*Wrapping inside a method avoids auto incrementing on every gradle task run. Now it runs only when we build apk*/
ext.autoIncrementBuildNumber = {

    if (versionPropsFile.canRead()) {
        def Properties versionProps = new Properties()
        versionProps.load(new FileInputStream(versionPropsFile))
        versionBuild = versionProps['VERSION_BUILD'].toInteger() + 1
        versionProps['VERSION_BUILD'] = versionBuild.toString()
        versionProps.store(versionPropsFile.newWriter(), null)
    } else {
        throw new GradleException("Could not read version.properties!")
    }
}