There seem to be no u helper on jruby, but you can use url_escape http://github.com/bougyman/url_escape

works_helper.rb

require 'url_escape'

module Fileservr::WorksHelper

  def new_work_path_with_session_information
    session_key = ActionController::Base.session_options[:key]
    new_fileservr_work_path(session_key => cookies[session_key], request_forgery_protection_token => form_authenticity_token)
  end

  def javascript_for_uploader
    session_key_name = ActionController::Base.session_options[:key]
    max_size = Parameter.get_parameter("maximum_filesize")
    code = " $(document).ready(function() {
      $('#work_asset').uploadify({
        'uploader': '/flash/uploadify.swf',
        'script': '#{ fileservr_works_path }',
        'scriptData': {
            'format': 'json',
            '#{ session_key_name }' : encodeURIComponent('#{URLEscape.escape cookies[session_key_name] }'),
            'authenticity_token'  : encodeURIComponent('#{URLEscape.escape form_authenticity_token if protect_against_forgery? }')
        },
        //'scriptAccess': 'always', // Incomment this, if for some reason it doesn't work·
        'multi': true,
        //'auto': true,
        'fileDesc': 'asset',
        'fileDataName' : $('#uploadr input:file')[0].name, // Extract correct name of upload field from form field
        //'fileExt': '*',
        'sizeLimit': #{max_size},
        'simUploadLimit': 1,
        //'buttonImg': '/images/button-fixed.png',
        buttonText : ' #{t("fileservr.works.new.choose_files") }',
        'cancelImg': '/images/cancel.png',
        onComplete    : function(event, queueID, fileObj, response, data) {
             var data = eval('(' + response + ')');
             //alert(data.asset);
             $.getScript(data.asset + '.js'
             )
        },
        onAllComplete : function(event, data){
          $('#uploadify_cancel').hide('blind');
          $('#uploadify_submit').show('blind');
        },
        onSelect: function(event, queueID, fileObj){
          if (fileObj.size > #{max_size}) {
            alert('The image' + fileObj.name + ' is too large.');
            return false;
          }
        }
      });

      $('#uploadify_submit').click(function(event){
        event.preventDefault();
        $('#work_asset').uploadifyUpload();
        $('#uploadify_submit').hide();
        $('#uploadify_cancel').show();
      });

      $('#uploadify_cancel').click(function(event){
        event.preventDefault();
        $('#work_asset').uploadifyClearQueue();
        $('#uploadify_cancel').hide();
        $('#uploadify_submit').show();
      });

    });"
  end

end