build.xml

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

  <property name="Extensions.dir" location="out" />
  <property name="AndroidRuntime-classes.dir" location="build/classes"/>
  <property name="ExternalComponent.dir" location="build/externalComponents" />
  <property name="ExternalComponent-class.dir" location="build/externalComponents-classes" />

  <target name="all" depends="extensions">
  </target>

  <target name="clean">
    <delete dir="build" />
    <delete dir="out" />
  </target>

  <taskdef resource="net/sf/antcontrib/antcontrib.properties">
    <classpath>
      <pathelement location="lib/ant-contrib/ant-contrib-1.0b3.jar"/>
    </classpath>
  </taskdef>

  <target name="javac">
    <mkdir dir="${AndroidRuntime-classes.dir}" />
    <depend srcdir="src" destdir="dest">
      <include name="**/*.java" />
    </depend>
    <javac target="7" source="7" destdir="${AndroidRuntime-classes.dir}" srcdir="src" encoding="utf-8"
           includeantruntime="false">
      <classpath>
        <pathelement location="lib/appinventor/AndroidRuntime.jar" />
        <pathelement location="lib/appinventor/AnnotationProcessors.jar" />
        <pathelement location="lib/kawa/kawa-1.11-modified.jar" />
        <fileset dir="lib/android">
          <include name="*.jar" />
        </fileset>
        <fileset dir="lib/deps">
          <include name="*.jar" />
        </fileset>
		        <fileset dir="lib/deps">
          <include name="*.aar" />
        </fileset>
      </classpath>
      <include name="**/*.java" />
    </javac>
  </target>

  <target name="process" depends="javac">
    <mkdir dir="${Extensions.dir}" />
    <mkdir dir="${ExternalComponent.dir}" />
    <mkdir dir="${ExternalComponent-class.dir}" />
    <java failonerror="true" classname="com.google.appinventor.components.scripts.ExternalComponentGenerator">
      <classpath>
        <pathelement location="lib/appinventor/AnnotationProcessors.jar" />
      </classpath>
      <arg path="${AndroidRuntime-classes.dir}/simple_components.json" />
      <arg path="${AndroidRuntime-classes.dir}/simple_components_build_info.json" />
      <arg path="${ExternalComponent.dir}" />
      <arg path="${AndroidRuntime-classes.dir}" />
      <arg path="lib/deps" />
      <arg path="${ExternalComponent-class.dir}" />
      <arg value="false" />
    </java>
  </target>

  <!-- =====================================================================
      unjarAllExtensionLibraries : Unjarring extension's library in order for the extensions'dex to work properly.
      ===================================================================== -->
  <target name="unjarAllExtensionLibraries">
    <foreach target="unjarExtensionLibraries" param="extension" inheritall="true">
      <path>
        <dirset dir="build/externalComponents-classes">
          <include name="*" />
        </dirset>
      </path>
    </foreach>
  </target>

  <target name="unjarExtensionLibraries">
    <basename property="extensionClassFolder" file="${extension}" />
    <unzip dest="build/externalComponents-classes/${extensionClassFolder}">
      <fileset dir="build/externalComponents-classes/${extensionClassFolder}">
        <include name="**/*.jar" />
		        <include name="**/*.aar" />
      </fileset>
    </unzip>
  </target>

  <!-- =====================================================================
     jarAllExtensions: create ${extension}.jar and AndroidRuntime.jar for each extension.
     ===================================================================== -->
  <target name="jarAllExtensions" depends="process,unjarAllExtensionLibraries" >
    <foreach target="jarExtension" param="extension" inheritall="true">
      <path>
        <dirset dir="${ExternalComponent-class.dir}">
          <include name="*" />
        </dirset>
      </path>
    </foreach>
  </target>

  <target name="jarExtension">
    <basename property="extensionClassFolder" file="${extension}" />
    <jar destfile="${ExternalComponent-class.dir}/${extensionClassFolder}.jar"
         basedir="${ExternalComponent-class.dir}/${extensionClassFolder}"
         includes="**/*.class"
         excludes="*.jar" />
    <antcall target="ProGuard">
      <param name="extensionClassFolder" value="${extensionClassFolder}" />
    </antcall>
    <copy file="${ExternalComponent-class.dir}/${extensionClassFolder}.jar"
          tofile="${ExternalComponent.dir}/${extensionClassFolder}/files/AndroidRuntime.jar"/>
    <echo>Generated build file AndroidRuntime.jar [${extensionClassFolder}]</echo>
  </target>

  <!-- =====================================================================
       dexAllExtensions: create classes.dex for each extension.
       ===================================================================== -->
  <target name="dexAllExtensions" depends="jarAllExtensions">
    <foreach target="dexExtension" param="extension">
      <path>
        <fileset dir="${ExternalComponent-class.dir}" >
          <include name="*.jar"/>
  </fileset>
       <fileset dir="${ExternalComponent-class.dir}" >
          <include name="*.aar"/>
        </fileset> 
 </path>
    </foreach>
  </target>

  <target name="dexExtension" depends="">
    <basename property="extensionType" file="${extension}" suffix=".jar"/>
    <java classname="com.android.tools.r8.D8"
          fork="true"
          failonerror="true">
      <classpath>
        <pathelement location="lib/android/d8.jar"/>
      </classpath>
<!--      TODO: add min api, android.jar lib, main dex list?-->
      <arg value="--release"/>
      <arg value="--output"/>
      <arg value="${ExternalComponent.dir}/${extensionType}/classes.jar"/>
      <arg value="${ExternalComponent-class.dir}/${extensionType}.jar"/>
    </java>
    <echo>Dexing extension: ${extensionType}</echo>
  </target>




  <!-- =====================================================================
      extensions: create ${extension}.aix for each external component.
       ===================================================================== -->
  <target name="packExtension">
    <basename property="extensionType" file="${extension}" />
    <zip destfile="${Extensions.dir}/${extensionType}.aix"
         basedir="${ExternalComponent.dir}"
         includes="${extensionType}/"
    />
  </target>

  <target name="extensions" depends="jarAllExtensions, dexAllExtensions">
    <mkdir dir="${Extensions.dir}" />
    <foreach target="packExtension" param="extension" inheritall="true">
      <path>
        <dirset dir="${ExternalComponent.dir}">
          <include name="*" />
        </dirset>
      </path>
    </foreach>
  </target>

  <!-- =====================================================================
       ProGuard: obfuscates and minifies the AndroidRuntime.jar file, containing
       the extensions source code. Only runs if the task has been called
       like "ant extensions -Dproguard=1".
       ===================================================================== -->

  <condition property="skipProguard">
    <not>
      <equals arg1="${proguard}" arg2="1" />
    </not>
  </condition>

  <target name="ProGuard" unless="skipProguard">
    <taskdef resource="proguard/ant/task.properties"
             classpath="lib/proguard/proguard.jar" />
    <proguard printmapping="out/${extensionClassFolder}-proguard.map"
              overloadaggressively="on"
              configuration="lib/proguard/proguard.cfg"
              ignorewarnings="false">

      <injar  file="${ExternalComponent-class.dir}/${extensionClassFolder}.jar" />
      <outjar file="${ExternalComponent-class.dir}/${extensionClassFolder}_p.jar" />

      <libraryjar>
        <fileset dir="lib">
          <include name="**/*.jar"/>
          <include name="**/*.aar"/>
        </fileset>
      </libraryjar>

      <dontnote filter="proguard.configuration.ConfigurationLogger" />
      <adaptresourcefilecontents filter="proguard/ant/task.properties" />
    </proguard>

    <delete file="${ExternalComponent-class.dir}/${extensionClassFolder}.jar" />
    <move file="${ExternalComponent-class.dir}/${extensionClassFolder}_p.jar"
          tofile="${ExternalComponent-class.dir}/${extensionClassFolder}.jar" />
  </target>

</project>