public   synchronized  Object getData(String s)
    {
        Object result =  null ;
         try 
        {
            URL url =  new  URL( this .getDocumentBase(), s);
            InputStream is = url.openStream();
             int  i =  0 ;
            ByteArrayOutputStream baos =  new  ByteArrayOutputStream();
             while ( (i = is.read()) != - 1  )
                baos.write(i);
             if ( baos.size() >  0 )
            {
                ByteArrayInputStream bais =  new  ByteArrayInputStream(baos.toByteArray());
                ObjectInputStream ois =  new  ObjectInputStream(bais);
                result = ois.readObject();
                ois.close();
                bais.close();
            }
        }
         catch (Exception e)
        {
            System.out.println("Error = " + e);
            e.printStackTrace();
        }
         return  result;
    }

    Map map =  new  HashMap();
    //... добавляем в map ...    
    ByteArrayOutputStream baos =  new  ByteArrayOutputStream();
    ObjectOutputStream oos =  new  ObjectOutputStream(baos);
    oos.writeObject(map);
    out.flush();
    out.close();