XML.java

package net.squiz.matrix.core;

import javax.xml.transform.stream.StreamSource;
import javax.xml.parsers.*;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;
import java.io.*;

public class XML {

    /* the static Document Builder instance */
    private static DocumentBuilder builder;

    // cannot instantiate
    private XML() {}

    public static DocumentBuilder getParser() throws SAXException {

        if (builder == null) {
            try {
                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                factory.setIgnoringElementContentWhitespace(false);
                builder = factory.newDocumentBuilder();
            } catch (ParserConfigurationException pce) {
                throw new SAXException("Error creating the document builder : "
                    + pce.getMessage());
            }
        }
        return builder;
    }

    public static synchronized Document getDocumentFromInputStream(InputStream is)
        throws SAXException {

        Document doc = null;
        DocumentBuilder db = getParser();

        if (is == null)
            throw new SAXException("Input Stream of XML source cannot be null");

        try {
            doc = db.parse(is);
        } catch (IOException se) {
            throw new SAXException("Could not create the document from the " +
                "Input Stream : " + se.getMessage());
        }

        if (doc.getDocumentElement().getTagName().equals("error"))
            throw new SAXException("Could not create the document");

        return doc;
    }

    public static synchronized Document getDocumentFromString(String xmlStr)
        throws SAXException {

        byte [] xmlArray = xmlStr.getBytes();
        ByteArrayInputStream xmlStream = new ByteArrayInputStream(xmlArray);

        StreamSource ss = new StreamSource(xmlStream);
        Document doc = null;

        try {
            doc = getDocumentFromInputStream(ss.getInputStream());
        } catch (SAXException se) {
            throw new SAXException("Could not create document from String: "
                + se.getMessage());
        }

        return doc;
    }
}