Connect to an oracle database using jdbc on JRuby in a jar file

This is how you can use JRuby to connect to an oracle database without requiring Ruby to be installed on the system, but only Java.

The JRuby interpreter and all necessary libraries will be packed into a single executable jar file. This is done “from scratch”, so if you need something more complex, consider gems like warbler, rawr and/or activerecord-jdbc-adapter.

1) Get the Java libraries

Get ojdbc6.jar from the oracle homepage (you need to create an oracle account…) and the JRuby interpreter:

wget -O jruby.jar https://jruby.org.s3.amazonaws.com/downloads/1.6.7.2/jruby-complete-1.6.7.2.jar

Store them in the same directory.

2) Prepare the jruby.jar to include oracle’s Java classes

unzip ojdbc6.jar
jar uf jruby.jar oracle

3) Use the boilerplate jdbc code from oracle (optional)

You can use jdbc_connection.rb (scroll down 2/5) from the oracle documentation to abstract away some low level code.

jar uf jruby.jar jdbc_connection.rb

4) Create a jar-bootstrap.rb file

This is the file that will be invoked when running the jar file from the command line.

touch jar-bootstrap.rb

5) Write some Ruby code that interacts with the database

Create the db connection with the code at (3) or with something like that:

require 'java'

java_import 'oracle.jdbc.OracleDriver'
java_import 'java.sql.DriverManager'

connection = java.sql.DriverManager.getConnection( # might raise errors
  "jdbc:oracle:thin:@host:port:db",
  "user",
  "password"
)

# use connection...

6) Package it all together

cp jruby.jar your.jar
# jar uf your.jar your.rb
jar ufe your.jar org.jruby.JarBootstrapMain jar-bootstrap.rb

You can add more .rb files to the jar, which can easily be required, because the jar root gets added to Ruby’s load path. However, require_relative won’t work.

7) Run it! :D

java -jar your.jar