custom_rules.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="custom_rules">

  <condition property="ndk.dir" value="${env.ANDROID_NDK}">
    <isset property="env.ANDROID_NDK" />
  </condition>

  <target name="-getgitdetails" >
    <exec executable="git" outputproperty="git.describe">
      <arg value="describe"/>
    </exec>
    <exec executable="git" outputproperty="git.revision">
      <arg value="rev-parse"/>
      <arg value="HEAD"/>
    </exec>
  </target>

  <target name="-javadoc" description="Generate Javadocs">
    <property name="javadoc.jar.name" value="${out.dir}/sqlcipher-javadoc.jar" />
    <javadoc sourcepath="${source.dir};gen"
             destdir="${out.dir}/javadoc"
             packagenames="net.sqlcipher.*"
             bootclasspath="${env.JAVA_HOME}/jre/lib/rt.jar"
             docletpath="${user.dir}/jars/doclava-1.0.6.jar" >
      <doclet name="com.google.doclava.Doclava">
        <param name="-hdf"/>
        <param name="project.name"/>
        <param name="SQLCipher for Android"/>
      </doclet>  
      <classpath>
        <fileset dir="${sdk.dir}/platforms/${target}">
            <include name="android.jar"/>
        </fileset>
    </classpath>
    </javadoc>
    <delete file="${javadoc.jar.name}"/>
    <jar destfile="${javadoc.jar.name}"
         includes="net/sqlcipher/**"
         basedir="${out.dir}/javadoc">
      <manifest>
        <attribute name="Implementation-Vendor" value="Zetetic"/>
        <attribute name="Implementation-Title" value="SQLCipher for Android"/>
        <attribute name="Implementation-URL" value="https://www.zetetic.net/sqlcipher/open-source"/>
        <attribute name="Implementation-Version" value="${git.describe}"/>
        <attribute name="Git-Revision" value="${git.revision}"/>
      </manifest>
    </jar>
  </target>

  <target name="-post-build" depends="-getgitdetails,-javadoc">
    <property name="jar.dir" value="libs" />
    <property name="jar.name" value="${jar.dir}/sqlcipher.jar" />
    <property file="${sdk.dir}/tools/source.properties" />
    <exec executable="cat" outputproperty="ndk.release">
      <arg value="${ndk.dir}/RELEASE.TXT"/>
    </exec>
    <delete file="${jar.name}"/>
    <mkdir dir="${jar.dir}" />
    <jar destfile="${jar.name}"
         includes="net/sqlcipher/**"
         basedir="${out.classes.absolute.dir}">
      <manifest>
        <attribute name="Implementation-Vendor" value="Zetetic"/>
        <attribute name="Implementation-Title" value="SQLCipher for Android"/>
        <attribute name="Implementation-URL" value="https://www.zetetic.net/sqlcipher/open-source"/>
        <attribute name="Implementation-Version" value="${git.describe}"/>
        <attribute name="Git-Revision" value="${git.revision}"/>
        <attribute name="Android-SDK-Release" value="${Pkg.Revision}"/>
        <attribute name="Android-SDK-Host-OS" value="${Archive.HostOs}"/>
        <attribute name="Android-NDK-Release" value="${ndk.release}"/>
      </manifest>
    </jar>
    <copy file="${out.dir}/sqlcipher-javadoc.jar" todir="${jar.dir}" preservelastmodified="true" overwrite="true"/>
  </target>

</project>