Shows how you can leverage some of Java's Java integration features. Original code from http://theblasfrompas.blogspot.com/2011/01/retrieving-dbmsoutput-from-plsql-in.html.

oracle_prepared.rb

require 'java'  
require 'C:/jdev/jdcbdrivers/11.2/ojdbc6.jar'  
require 'lib/jdbc_connection'  
require 'lib/dbms_output'
  

# v--- java_import is better than import if you end up using rake for testing
# v--- java,org,edu,javax can all be supplied bare-word instead of string form
java_import java.sql.CallableStatement
java_import java.sql.Connection
java_import java.sql.SQLException
java_import java.sql.Types
# v--- but note we cannot bareword here because of package name 'oracle'
java_import 'oracle.jdbc.OracleDriver'

PLSQL_BLOCK = <<EOF
begin 
for i in 1..10 loop
  dbms_output.put_line('Hello JRuby at position '||i);
end loop;
end;
EOF

SHOW_STATEMENT = <<EOF
declare
  l_line varchar2(255);
  l_done number;
  l_buffer long;
begin
  loop
  exit when length(l_buffer)+255 > :maxbytes OR l_done = 1;
    dbms_output.get_line( l_line, l_done );
    l_buffer := l_buffer || l_line || chr(10);
  end loop;
 :done := l_done;
 :buffer := l_buffer;
end;
EOF

class OracleConnection   
  def initialize(user, passwd, url)  
    @user, @passwd, @url = user, passwd, url
      
    # v--- we can inline full package names if we want
    java.sql.DriverManager.registerDriver OracleDriver.new # load driver class

    # v--- We can use camel-case like getConnection
    @connection = DriverManager.getConnection url, user, passwd
    # v--- Java method turned into snake-cased setter
    #  ... setAutoCommit can also be 'set_auto_commit' or 'auto_commit ='
    @connection.auto_commit = false
  end  
   
  # add getters and setters for all attrributes we wish to expose  
  attr_reader :user, :passwd, :url, :connection

  def prepare_call(call)
    @connection.prepare_call call
  end

  def create_statement()
    @connection.create_statement
  end

  def close
    @connection.close unless @connection
  end
  
  def to_s  
    "OracleConnection [user=#{@user}, passwd=#{@passwd}, " +  
    "url=#{@url}]"  
  end  

  def self.create(user, passwd, url)
    conn = new(user, passwd, url)
    yield conn
  rescue
    puts "\n** Error occured **\n"  
    puts "Failed executing Oracle JDBC DBMS_OUTPUT demo from JRuby ", $!, "\n"
  ensure
    conn.close
  end
end

class DbmsOutput  
  def initialize(conn)  
    @enable_stmt = conn.prepare_call "begin dbms_output.enable(:1); end;"
    @disable_stmt = conn.prepare_call "begin dbms_output.disable; end;"
    @show_stmt = conn.prepare_call SHOW_STATEMENT 
  end  
    
  def enable (size)  
    @enable_stmt.set_int 1, size
    @enable_stmt.execute_update
  end  
    
  def disable  
    @disable_stmt.execute_update
  end  
    
  def show  
    output = ""  
    
    @show_stmt.register_out_parameter 2, 4
    @show_stmt.register_out_parameter 3, 12
    
    loop do
      @show_stmt.set_int 1, 32000
      @show_stmt.execute_update
      output += "#{@show_stmt.get_string(3)}\n"  
      break if @show_stmt.get_int(2).to_i == 1   
    end  
        
    output  
  end  
    
  def close_all  
    @enable_stmt.close
    @disable_stmt.close
    @show_stmt.close
  end

  def self.create(connection)
    dbms_output = new(connection)
    yield dbms_output
  ensure
    dbms_output.close_all
  end
end


user = "scott"
passwd = "tiger"
url = "jdbc:oracle:thin:@beast.au.oracle.com:1524/linux11gr2"

print "Run at #{Time.now} using JRuby #{RUBY_VERSION}\n\n"  

OracleConnection.create(user, passwd, url) do |conn|
  DbmsOutput.create(conn) do |dbms_output|
      dbms_output.enable 1000000
      
      conn.create_statement.execute(PLSQL_BLOCK)
  
      puts "** Output from PLSQL Block as follows **"  
      puts dbms_output.show
    end
end

print "Ended at #{Time.now}"