Update to create a complete build environment

Dockerfile

@@ -1,24 +1,40 @@
-FROM openjdk:8-jdk
-ENV JRE_DIR=/usr/local/openjdk-8/jre
+# See: https://hub.docker.com/r/romraider/builder Overview for run details
+
+FROM --platform="linux/386" i386/ubuntu:18.04 AS rr_builder
 
 RUN apt-get -y update && \
     apt-get -y upgrade && \
-    apt-get -y install ant
+    apt-get -y install ant openjdk-8-jdk unzip && \
+    apt-get clean
 
-ENV maven_url="https://search.maven.org/remotecontent?filepath="
-ENV junit_url="${maven_url}junit/junit/4.13.2/junit-4.13.2.jar"
-ENV hamcrest_core_url="${maven_url}org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar"
+ENV JAVA_HOME=/usr/lib/jvm/java-8-openjdk-i386/jre
+RUN /usr/bin/update-alternatives --set java ${JAVA_HOME}/bin/java
 
-RUN curl -Lo ${JRE_DIR}/lib/junit.jar ${junit_url} && \
-    curl -Lo ${JRE_DIR}/lib/hamcrest-core.jar ${hamcrest_core_url}
+RUN useradd -ms /bin/bash romraider && \
+    mkdir /home/romraider/RomRaider && \
+    mkdir /home/romraider/java && \
+    chown romraider:romraider /home/romraider/RomRaider && \
+    chown romraider:romraider /home/romraider/java
 
-RUN useradd -m romraider
-WORKDIR /home/romraider
-USER romraider
+WORKDIR /home/romraider/java
+ARG JAVA6_SRC=jre-6u45-windows-i586.zip
+ADD --chown=romraider:romraider https://romraider.com/roms/dl.php?file=${JAVA6_SRC} ./${JAVA6_SRC}
 
-COPY --chown=romraider . /home/romraider/RomRaider/
+USER romraider:romraider
+RUN unzip -q /home/romraider/java/${JAVA6_SRC}
 
+ARG maven_url="https://search.maven.org/remotecontent?filepath="
+ARG junit_url="${maven_url}junit/junit/4.13.2/junit-4.13.2.jar"
+ARG hamcrest_core_url="${maven_url}org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar"
+ENV JRE_DIR=/home/romraider/java
+
+USER root
+ADD ${junit_url} ${JRE_DIR}/lib/junit.jar
+ADD ${hamcrest_core_url} ${JRE_DIR}/lib/hamcrest-core.jar
+RUN chmod 644 ${JRE_DIR}/lib/junit.jar && \
+    chmod 644 ${JRE_DIR}/lib/hamcrest-core.jar
+
+USER romraider:romraider
 WORKDIR /home/romraider/RomRaider
-
-RUN ant unittest && \
-    ant build-linux
+RUN java -version && \
+    echo "RomRaider build environment created."