Gemfile

gem 'rsolr-direct', '~> 0.1.0', :require => nil

rsolr_direct.rb

if RUBY_PLATFORM =~ /java/

  require 'rsolr-direct'
  ::RSolr.load_java_libs

  ::Sunspot.session.instance_variable_set(:@connection,
    ::RSolr.connect(
      :direct,
      :solr_home => File.join(RAILS_ROOT, 'solr'),
      :data_dir =>  File.join(RAILS_ROOT, 'solr', 'data', RAILS_ENV)
    )
  )

end