XML String to Hashtable

XML2Hashtable.java

import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Hashtable;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

public class XML2Hashtable {
	@SuppressWarnings("unchecked")
	public static void main(String[] args) throws Exception {
		StringBuilder sb = new StringBuilder();
		sb.append("<?xml version=\"1.0\" encoding=\"UTF-8\" ?>");
		sb.append("<companies>");
		sb.append("<company>");
		sb.append("<name>example.com</name>");
		sb.append("<url>http://www.example.com/</url>");
		sb.append("</company>");
		sb.append("<company>");
		sb.append("<name>example.jp</name>");
		sb.append("<url>http://www.example.jp/</url>");
		sb.append("</company>");
		sb.append("</companies>");
		String xmlString = sb.toString();

		InputSource is = new InputSource();
		is.setCharacterStream(new StringReader(xmlString));
		DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = factory.newDocumentBuilder();
		Document document = builder.parse(is);
		{
			Hashtable<String, Object> obj = (Hashtable<String, Object>) node2hash(document);
			Hashtable<String, Object> companies = (Hashtable<String, Object>) obj.get("companies");
			ArrayList<Hashtable<String, Object>> nlist = (ArrayList<Hashtable<String, Object>>) companies
					.get("company");
			for (int i = 0; i < nlist.size(); i++) {
				System.out.println("--- " + i + " ---");
				System.out.println(nlist.get(i).get("url"));
			}
		}
		{
			NodeList nlist = evaluateXPath("//company", document);
			for (int i = 0; i < nlist.getLength(); i++) {
				System.out.println("--- " + i + " ---");
				System.out.println(node2hash(nlist.item(i)).get("url"));
			}
		}
		{
			NodeList nlist = evaluateXPath("//company/url/text()", document);
			for (int i = 0; i < nlist.getLength(); i++) {
				System.out.println("--- " + i + " ---");
				System.out.println(nlist.item(i).getNodeValue());
			}
		}
	}

	public static NodeList evaluateXPath(String xpathString, Document doc) throws IOException {
		try {
			XPathFactory factory = XPathFactory.newInstance();
			XPath xpath = factory.newXPath();
			return (NodeList) xpath.evaluate(xpathString, doc, XPathConstants.NODESET);
		} catch (XPathExpressionException e) {
			throw new IOException(e.getMessage());
		}
	}

	private static ArrayList<Node> childElements(Node node) {
		NodeList nlist = node.getChildNodes();
		ArrayList<Node> ret = new ArrayList<Node>();
		for (int i = 0; i < nlist.getLength(); i++) {
			Node n = nlist.item(i);
			if (n.getNodeType() == Node.ELEMENT_NODE)
				ret.add(n);
		}
		return ret;
	}

	@SuppressWarnings("unchecked")
	private static Hashtable<String, Object> node2hash(Node node) {
		Hashtable<String, Object> ret = new Hashtable<String, Object>();
		ArrayList<Node> cnodes = childElements(node);
		for (Node n : cnodes) {
			ArrayList<Node> cn = childElements(n);
			String name = n.getNodeName();
			if (cn.size() > 0) {
				if (ret.containsKey(name)) {
					Object o = ret.get(name);
					if (o instanceof Hashtable) {
						ArrayList<Hashtable<String, Object>> ary = new ArrayList<Hashtable<String, Object>>();
						ret.put(name, ary);
						ary.add((Hashtable<String, Object>) o);
						ary.add(node2hash(n));
					} else if (o instanceof ArrayList) {
						((ArrayList<Hashtable<String, Object>>) o).add(node2hash(n));
					}
				} else {
					ret.put(name, node2hash(n));
				}
			} else {
				ret.put(name, n.getFirstChild().getNodeValue());
			}
		}
		return ret;
	}
}