使用Sax解析大型XML文件

Question

i am trying to parse an xml document, after searching i found out that sax is the best choice, but the document is very large (1.5 GB) waited like 7 minutes but its still running my question is, is that normal ? or i can do better ?

public static void main(String argv[]) {

    try {

        SAXParserFactory factory = SAXParserFactory.newInstance();
        SAXParser saxParser = factory.newSAXParser();

        DefaultHandler handler = new DefaultHandler() {

            int c = 0;
            boolean id = false;
            boolean value = false;
            boolean orgin = false;
            boolean note = false;

            @Override
            public void startElement(String uri, String localName, String eName,
                    Attributes attributes) throws SAXException {

                if (eName.equalsIgnoreCase("ID")) {
                    id = true;
                }

                if (eName.equalsIgnoreCase("VALUE")) {
                    value = true;
                }

                if (eName.equalsIgnoreCase("ORGIN")) {
                    orgin = true;
                }

                if (eName.equalsIgnoreCase("NOTE")) {
                    note = true;
                }

            }

            @Override
            public void endElement(String uri, String localName,
                    String eName) throws SAXException {

            }

            @Override
            public void characters(char ch[], int start, int length) throws SAXException {

                if (id) {
                    System.out.println(new String(ch, start, length));
                    id = false;
                    System.out.println("record num : "+c++);
                }

                if (value) {
                    System.out.println(new String(ch, start, length));
                    value = false;
                }

                if (orgin) {
                    System.out.println(new String(ch, start, length));
                    orgin = false;
                }

                if (note) {
                    System.out.println(new String(ch, start, length));
                    note = false;
                }

            }

        };

        saxParser.parse("./transactions.xml", handler);

    } catch (Exception e) {
        e.printStackTrace();
    }

}

Answer 1

1. You can save some time by changing equalsIgnoreCase to equals (unless you really encounter "ValuE" and "valUE" and "VaLuE" ...)
2. The printing is probably taking most of the time. IO operations are usually the bottleneck

Answer 2

If you parse such a huge file you should use Stax instead of Sax. With Stax you can skip parts of your file which makes it faster and it's faster.

StAX is a "pull" type of API. As discussed, there are Cursor and Event Iterator APIs. There are both reading and writing sides of the API. It is more developer friendly than SAX. StAX, like SAX, does not require an entire document to be held in memory. However, unlike SAX, an entire document need not be read. Portions can be skipped. This may result in even improved performance over SAX.

( DOM vs SAX XML parsing for large files )