Spikes Of Nothingness - Ruby category

extra 5 minutes of fun; JRuby and Velocity

Fri, 06 Nov 2009 17:15:41 GMT

As promised, this time I am showing you a very simple way to play with Velocity templating language in JRuby.

jvel.rb

# A simple JRuby Velocity integration demo 
# Notes: 
# - save this script as 'jvel.rb'.
# - in the folder from where you're executing this simple script, you'll
#  have a subfolder: 'lib', containing the Velocity library:
#   lib/velocity-1.6.2-dep.jar
# This jar is intended to be used when you do standalone development
# with Velocity. And assuming that you have jruby in the path, you can 
# run the script:
#
#   $ jruby jvel.rb World
#
# You'll see: Hello World!
# ----------- 

require 'java'   

Dir["lib/*.jar"].each { |jar| require jar }
 
class JRubyVelocity   
    include_class 'java.io.StringWriter'   
    include_class 'org.apache.velocity.app.Velocity'   
    include_class 'org.apache.velocity.VelocityContext'    

  def render ( arg) 
    Velocity.init
    writer = StringWriter.new  
    ctx = VelocityContext.new( {'name' => arg})                      
    Velocity.evaluate( ctx, writer, "log", "Hello ${name}!") 
    return writer.getBuffer
  end
end  

puts JRubyVelocity.new().render( ARGV.pop)

Good luck!

5 minutes of fun: JRuby and StringTemplate

Wed, 04 Nov 2009 18:01:07 GMT

If you like to explore some stuff on templating, and I highly recommend StringTemplate, this is how you can do it from JRuby.

jrst.rb

# A simple JRuby StringTemplate integration demo 
# Notes: 
# - save this script as 'jrst.rb'.
# - in the folder from where you're executing this simple script, you'll
#  have a subfolder: 'lib', containing the StringTemplate libraries:
#    lib/antlr-2.7.7.jar
#    lib/stringtemplate-3.2.1.jar
# run the script
# $ jruby jrst.rb World
#
# You'll see: Hello World!
# ----------- 
require 'java'   

Dir["lib/*.jar"].each { |jar| require jar }

class JRubySringTemplate
  include_class 'java.io.StringWriter'   
  include_class 'org.antlr.stringtemplate.StringTemplate'    

  def render ( arg)                         
    st = StringTemplate.new("Hello $name$!")
    st.set_attributes( {'name' => arg});
    writer = StringWriter.new   
    writer.write( st.toString)
    return writer.getBuffer
  end 
end

puts JRubySringTemplate.new().render( ARGV[0])

My 5 minutes of fun in a lunch break. Next time I'll show you how to use Velocity in the same way :)

Have fun!

JRuby actions in JPublish

Tue, 17 Jul 2007 20:47:15 GMT

As some of you already know, JPublish can execute actions written in JRuby. This is all possible through the magic of the BSF :)

I received a lot of questions about how can a JRuby Action use the java objects available in the JPublishContext?

There's nothing simpler than that, in JPublish is easy :) Below is the body of a JRuby Action which will print a message to the designated console log and will populate the page context with the variable "hello". The variable "hello" will be accessible to Velocity or Freemarker during the post action execution rendering process.

HelloJRuby.rb

require 'java'
$syslog.info("HelloJRuby.rb action ...")
$context.put("hello", "Hello World!")

Simple, eh? Use the dollar sign in front of the variables you expect to find in the context.

Also, there is a recent web site with a lot of JRuby news and tips, check it out in case you're interested. Is called JRuby Inside.

Cheers!