XslBookProcessor.java

package nl.siegmann.epublib.bookprocessor;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import nl.siegmann.epublib.domain.Book;
import nl.siegmann.epublib.domain.Resource;
import nl.siegmann.epublib.epub.BookProcessor;
import nl.siegmann.epublib.epub.EpubProcessorSupport;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;


/**
 * Uses the given xslFile to process all html resources of a Book.
 * 
 * @author paul
 *
 */
public class XslBookProcessor extends HtmlBookProcessor implements BookProcessor {

	private final static Logger log = LoggerFactory.getLogger(XslBookProcessor.class); 

	private Transformer transformer;
	
	public XslBookProcessor(String xslFileName) throws TransformerConfigurationException {
		File xslFile = new File(xslFileName);
		TransformerFactory transformerFactory = TransformerFactory.newInstance();
		transformer = transformerFactory.newTransformer(new StreamSource(xslFile));
	}

	@Override
	public byte[] processHtml(Resource resource, Book book, String encoding) throws IOException {
		byte[] result = null;
		try {
		DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
	    DocumentBuilder db = dbFactory.newDocumentBuilder();
	    db.setEntityResolver(EpubProcessorSupport.getEntityResolver());

	    Document doc = db.parse(new InputSource(resource.getReader()));
	    
	    Source htmlSource = new DOMSource(doc.getDocumentElement());
	    ByteArrayOutputStream out = new ByteArrayOutputStream();
	    Writer writer = new OutputStreamWriter(out, "UTF-8");
	    Result streamResult = new StreamResult(writer);
	    try {
	    	transformer.transform(htmlSource, streamResult);
	    } catch (TransformerException e) {
	    	log.error(e.getMessage(), e);
	    	throw new IOException(e);
	    }
	    result = out.toByteArray();
	    return result;
		} catch (Exception e) {
			throw new IOException(e);
		}
	}
}