Java: splitting up a large XML file with SAXParser

Question

Hi All,

I am trying to split a large XML file into smaller files using java's SAXParser (specifically the wikipedia dump which is about 28GB uncompressed).

I have a Pagehandler class which extends DefaultHandler:

private class PageHandler extends DefaultHandler {

   private StringBuffer text;
   ...

  @Override
  public void startElement(String uri, String localName, String qName, Attributes attributes) {

        text.append("<" + qName + ">");
  }

  @Override
  public void endElement(String uri, String localName, String qName) {

        text.append("</" + qName + ">");

        if (qName.equals("page")) {
            text.append("\n");
            pageCount++;
            writePage();
        }

        if (pageCount >= maxPages) {
            rollFile();
        }
    }

  @Override
  public void characters(char[] chars, int start, int length) {
        for (int i = start; i < start + length; i++) {
            text.append(chars[i]);
        }
    }
}

So I can write out element content no problem. My problem is how to get the element tags and attributes - these characters do not seem to be reported. At best I will have to reconstruct these from what's passed as arguments to startElement - which seems a bit of a a pain. Or is there an easier way?

All I want to do is loop through the file and write it out, rolling the output file every-so-often. How hard can this be :)

Thanks

Answer 1

I'm not quite sure I totally understand what you are trying to do but to get the qualified name as a string you simply do qName.toString() and to get the attributes name you just do atts.getQName(int index).

Answer 2

The problem here is that you're writing the XML elements out yourself. Have a look at the XMLWriter class of dom4j - while it's a little old, it makes it really easy to output XML documents by calling its startElement and endElement methods.