download docker image and unpack jdk

docker.update_jdk.bash

#!/usr/bin/env bash

JDK_TAG=8_jdk-dcevm_unlimited
DOCKER_IMAGE='anapsix/alpine-java:'$JDK_TAG
JDK_HOME=~/bin/$JDK_TAG

docker pull ${DOCKER_IMAGE}

update_jdk() {
	echo 'update JDK version...'

	mkdir -p $JDK_HOME
	rm -Rf $JDK_HOME/*

	docker run -it -v ${JDK_HOME}:/opt/ext_jdk ${DOCKER_IMAGE} /bin/bash -c "cp -R /opt/jdk/* /opt/ext_jdk/; chown -R $(id -u):$(id -g) /opt/ext_jdk/"
}

if [ ! -d "$JDK_HOME" ] || [ ! "$(ls -A ${JDK_HOME})" ]
then
	echo 'not found local JDK'
	update_jdk
fi

LOCAL_VERSION="$(${JDK_HOME}/bin/java -version 2>&1 | head -n 1 | awk -F '"' '{print $2}')"
DOCKER_VERSION="$(echo "$(docker run -it $DOCKER_IMAGE /opt/jdk/bin/java -version 2>&1)" | head -n 1 | awk -F '"' '{print $2}')"

if [ ! $LOCAL_VERSION == $DOCKER_VERSION ]
then
	echo 'local JDK not equals docker JDK'
	update_jdk
fi

echo "jdk local version: ${LOCAL_VERSION}"
echo "jdk docker version: ${DOCKER_VERSION}"
echo "--- local jdk version ---"
${JDK_HOME}/bin/java -version