How to install OpenGrok in ubuntu 14?

Android OpenGrok:
http://androidxref.com/

How to install OpenGrok?
Download it from http://opengrok.github.io/OpenGrok/
and decompression to /opt/opengrok

Requirements:

• Latest Java 1.8
• A servlet container like GlassFish or Tomcat (8.x or later) also running with Java at least 1.8
• Exuberant Ctags

download jdk 1.8 and decompression to /usr/lib/jvm/jdk1.8.0_131
download tomcat9 and decompression to /var/lib/tomcat9
use startup.sh to start tomcat, see the result by http://localhost:8080

set environment variables as follows：

export JAVA_HOME="/usr/lib/jvm/jdk1.8.0_131"
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=.:$CLASSPATH:$JAVA_HOME/lib:$JAVA_HOME/jre/lib
export PATH=$PATH:$JAVA_HOME/bin:$JAVA_HOME/jre/bin

export OPENGROK_INSTANCE_BASE=/opt/opengrok
export SCRIPT_DIRECTORY=$OPENGROK_INSTANCE_BASE/bin
export PATH=$PATH:$SCRIPT_DIRECTORY
export OPENGROK_DISTRIBUTION_BASE=$OPENGROK_INSTANCE_BASE/lib

export SRC_ROOT=/home/ds/project/opengrok
export DATA_ROOT=$OPENGROK_INSTANCE_BASE/data

export EXUB_CTAGS=/usr/bin/ctags

export OPENGROK_APP_SERVER=Tomcat
export OPENGROK_TOMCAT_BASE=/var/lib/tomcat9
export OPENGROK_WAR_TARGET_TOMCAT=$OPENGROK_TOMCAT_BASE/webapps
export OPENGROK_WAR_TARGET=$OPENGROK_TOMCAT_BASE/webapps
export CATALINA_HOME=$OPENGROK_TOMCAT_BASE

Follow instructions as follows：
OpenGrok deploy
OpenGrok index /home/ds/project/opengrok
see the result by http://localhost:8080/source/

需要注意的是版本要匹配！