比较两段 HTML 的差异

/**
 * 比较两段 HTML 的差异
 * @param html1
 * @param html2
 * @return
 * @throws SAXException 
 * @throws IOException 
 * @throws TransformerConfigurationException 
 */
public static String diff(String html1, String html2) throws IOException, SAXException, TransformerConfigurationException {
	
	ByteArrayOutputStream baos = new ByteArrayOutputStream();

    SAXTransformerFactory tf = (SAXTransformerFactory) TransformerFactory.newInstance();

    TransformerHandler result = tf.newTransformerHandler();
    result.setResult(new StreamResult(baos));

    Locale locale = Locale.getDefault();

    HtmlCleaner cleaner = new HtmlCleaner();

    InputSource oldSource = new InputSource(new StringReader(html1));
    InputSource newSource = new InputSource(new StringReader(html2));

    DomTreeBuilder oldHandler = new DomTreeBuilder();
    cleaner.cleanAndParse(oldSource, oldHandler);
    TextNodeComparator leftComparator = new TextNodeComparator(oldHandler, locale);

    DomTreeBuilder newHandler = new DomTreeBuilder();
    cleaner.cleanAndParse(newSource, newHandler);
    TextNodeComparator rightComparator = new TextNodeComparator(newHandler, locale);

    result.startDocument();
    
    HtmlSaxDiffOutput output = new HtmlSaxDiffOutput(result, null);
    
    HTMLDiffer differ = new HTMLDiffer(output);
    differ.diff(leftComparator, rightComparator);
    result.endDocument();
    
    String html = baos.toString();
    
    return html.substring(38); //get rid of "
 "
}