code: public void transferItem() {
      Metadata metadata = metadatas.get(index);
      List<?> values = (List<?>) ((List<?>) context.get("items")).get(index);
      getWriter().writeTitle(metadata.dataName, metadata.titles);
      Object[] propValues = new Object[metadata.attrs.length];
      for (Object item : values) {
        for (int i = 0; i < propValues.length; i++) {
          try {
            propValues[i] = propertyExtractor.getPropertyValue(item, metadata.attrs[i]);
          } catch (Exception e) {
            transferResult.addFailure(TransferMessage.ERROR_ATTRS_EXPORT,
                "occur in get property :" + metadata.attrs[i] + " and exception:" + e.getMessage());
          }
        }
        writer.write(propValues);
      }
    }
docs: <p>
  transferItem.
  </p>