java使用SAX解析xml

import java.io.File;
import java.util.LinkedList;
import java.util.List;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class ParseXMLFileWithSAX extends DefaultHandler {

private StringBuffer buffer = new StringBuffer();

    private static String responseCode;
    private static String date;
    private static String title;

    private static Currency currency;
    private static Rates rates;

    public static void main(String[] args) throws Exception {

        DefaultHandler handler = new ParseXMLFileWithSAX();

        SAXParserFactory factory = SAXParserFactory.newInstance();
        factory.setValidating(false);

        SAXParser parser = factory.newSAXParser();

        parser.parse(new File("in.xml"),handler);

        System.out.println("Response Code:" + responseCode);
        System.out.println("Date:" + date);
        System.out.println("Title:" + title);
        System.out.println("Rates:");

        for (Currency curr : rates.currencies) {
            System.out.println("tCode:" + curr.code + " - Rate:" + curr.rate);
        }

    }

    private static class Currency {
        public String code;
        public String rate;
    }

    private static class Rates {
        public List<Currency> currencies = new LinkedList<Currency>();
    }

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

        buffer.setLength(0);

        if (qName.equals("response")) {
            responseCode = attributes.getValue("code");
        }
        else if (qName.equals("date")) {
            date = "";
        }
        else if (qName.equals("title")) {
            title = "";
        }
        else if (qName.equals("rates")) {
            rates = new Rates(); 
        }
        else if (qName.equals("currency")) {
            currency = new Currency(); 
        }

    }

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

        if (qName.equals("date")) {
            date = buffer.toString();
        }
        else if (qName.equals("title")) {
            title = buffer.toString();
        }
        else if (qName.equals("currency")) {
            rates.currencies.add(currency);
        }
        else if (qName.equals("code")) {
            currency.code = buffer.toString();
        }
        else if (qName.equals("rate")) {
            currency.rate = buffer.toString();
        }

    }

    public void characters(char[] ch,int start,int length) {
        buffer.append(ch,start,length);
    }

}

<?xml version="1.0" encoding="UTF-8" ?>
<response code="200">
    <date>2008-11-07</date>
    <title>Exchange rates for 2008-11-07</title>
    <rates>
        <currency>
            <code>EUR</code>
            <rate>1.220</rate>
        </currency>
        <currency>
            <code>USD</code>
            <rate>1.275</rate>
        </currency>
    </rates>
</response>

Response Code:200
Date:2008-11-07
Title:Exchange rates for 2008-11-07
Rates:
    Code:EUR - Rate:1.0
    Code:USD - Rate:1.275600