title: How do I correctly add to the CLASSPATH in a JRuby on Rails project?
body: <p>I've added some external jars to my CLASSPATH by adding this in <code>config/application.rb</code>:</p>
  
  <pre><code>require 'java'
  $CLASSPATH &lt;&lt; "#{File.dirname(__FILE__)}/../backend/src/"
  Dir["#{File.dirname(__FILE__)}/../backend/lib/*.jar"].each do |jar|
     require jar
  end
  </code></pre>
  
  <p>This works fine when running Rails using <code>rails server</code>. The jars from the CLASSPATH are loaded. However, when running <code>rake</code> the classpath is not set. How can I set it? In particular, I need to set it before loading my gems, since I use the JRClj gem, which relies on already having clojure.jar in my CLASSPATH.</p>
  
  <p>(Oh, I also tried putting the code in environment.rb; didn't help)</p>
  
  <p>By "not work", I mean:</p>
  
  <pre><code>$ rake rspec --trace
  rake aborted!
  No such file to load -- /MY_CURRENT_WORKING_DIRECTORY/clojure.lang.RT
  org/jruby/RubyKernel.java:1063:in `load'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/activesupport-3.1.1/lib/active_support/dependencies.rb:234:in `load'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/activesupport-3.1.1/lib/active_support/dependencies.rb:223:in `load_dependency'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/activesupport-3.1.1/lib/active_support/dependencies.rb:640:in `new_constants_in'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/activesupport-3.1.1/lib/active_support/dependencies.rb:639:in `new_constants_in'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/activesupport-3.1.1/lib/active_support/dependencies.rb:223:in `load_dependency'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/activesupport-3.1.1/lib/active_support/dependencies.rb:234:in `load'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load_rakefile'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/default_loader.rb:6:in `load'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:569:in `load_imports'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:508:in `raw_load_rakefile'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:82:in `load_rakefile'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:81:in `load_rakefile'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:65:in `run'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/gems/rake-0.9.2.2/bin/rake:33:in `(root)'
  org/jruby/RubyKernel.java:1063:in `load'
  /Users/pbiggar/.rvm/gems/jruby-1.6.5@jruby-clojure-combination/bin/rake:19:in `(root)'
  </code></pre>