code: @Override
      public void characters(char[] ch, int start, int length) throws SAXException {
          contentBuffer.append(String.copyValueOf(ch, start, length));
      }
docs: Fires one or more times for each text node encountered. It saves text
  informations in contentBuffer.
  
  @param ch The characters from the XML document
  @param start The start position in the array
  @param length The number of characters to read from the array
  @throws SAXException Any SAX exception, possibly wrapping another
  exception