source: greenstone3/trunk/src/java/org/greenstone/gsdl3/util/XMLTransformer.java@ 17024

/*
 *    XMLTransformer.java
 *    Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.greenstone.gsdl3.util;

// XML classes
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;

import javax.xml.transform.stream.StreamSource;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.dom.DOMResult;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Element;
import org.w3c.dom.Document;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

// other java classes
import java.io.StringReader;
import java.io.StringWriter;
import java.io.File;
import java.util.HashMap;
import java.util.Set;
import java.util.Map;
import java.util.Iterator;

import org.apache.xml.utils.DefaultErrorHandler;

import org.apache.log4j.*;

/** XMLTransformer - utility class for greenstone
 *
 * transforms xml using xslt
 *
 * @author <a href="mailto:[email protected]">Katherine Don</a>
 * @version $Revision: 17024 $
 */
public class XMLTransformer {

    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.XMLTransformer.class.getName());

  /** The transformer factory we're using */
    TransformerFactory t_factory=null;
  
  /**
   * The no-arguments constructor. 
   *
   * Any exceptions thrown are caught internally
   * 
   * @see javax.xml.transform.TransformerFactory
   */
    public XMLTransformer() {

    // make sure we are using the xalan transformer
    System.setProperty("javax.xml.transform.TransformerFactory", "org.apache.xalan.processor.TransformerFactoryImpl");
    try {
        this.t_factory = org.apache.xalan.processor.TransformerFactoryImpl.newInstance();

    } catch (Exception e) {
        logger.error("exception "+e.getMessage());
    }
    }

 
    
  /**
   * Transform an XML document using a XSLT stylesheet
   * 
   * @param stylesheet a filename for an XSLT stylesheet
   * @param xml_in the XML to be transformed
   * @return the transformed XML
   */
    public String transform(String stylesheet, String xml_in) {
    
    try {
        // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
        Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));

        // Use the Transformer to transform an XML Source and send the output to a Result object.
        StringWriter output = new StringWriter();

        transformer.transform(new StreamSource(new StringReader(xml_in)), new StreamResult(output));
        return output.toString();
    } catch (TransformerConfigurationException e) {
        logger.error("couldn't create transformer object: "+e.getMessageAndLocation());
        logger.error(e.getLocationAsString());  
        return "";
    } catch (TransformerException e) {
        logger.error("couldn't transform the source: " + e.getMessage());
        return "";
    }   
    }

    public String transformToString(Document stylesheet, Document source) {
    return transformToString(stylesheet, source, null);
    }
    
    public String transformToString(Document stylesheet, Document source, HashMap parameters) {
    
    try {
        // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
        Transformer transformer = this.t_factory.newTransformer(new DOMSource(stylesheet));
        if (parameters != null) {
        Set params = parameters.entrySet();
        Iterator i = params.iterator();
        while (i.hasNext()) {
            Map.Entry m = (Map.Entry)i.next();
            transformer.setParameter((String)m.getKey(), m.getValue());
        }
        }
        //transformer.setParameter("page_lang", source.getDocumentElement().getAttribute(GSXML.LANG_ATT));

        
        // Use the Transformer to transform an XML Source and send the output to a Result object.
        StringWriter output = new StringWriter();
        
        transformer.transform(new DOMSource(source), new StreamResult(output));
        return output.toString();
    } catch (TransformerConfigurationException e) {
        logger.error("couldn't create transformer object: "+e.getMessageAndLocation());
        logger.error(e.getLocationAsString());  
        return "";
    } catch (TransformerException e) {
        logger.error("couldn't transform the source: " + e.getMessage());
        return "";
    }   
      }

    public Node transform(Document stylesheet, Document source) {
    return transform(stylesheet, source, null);
    }

    public Node transform(Document stylesheet, Document source, HashMap parameters) {

    try {
        // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
        Transformer transformer = this.t_factory.newTransformer(new DOMSource(stylesheet));
        
        if (parameters != null) {
        Set params = parameters.entrySet();
        Iterator i = params.iterator();
        while (i.hasNext()) {
            Map.Entry m = (Map.Entry)i.next();
            transformer.setParameter((String)m.getKey(), m.getValue());
        }
        }

        DOMResult result = new DOMResult();
        transformer.transform(new DOMSource(source), result);
        return result.getNode().getFirstChild();
    } catch (TransformerConfigurationException e) {
        String message = "TransformerConfigurationException: "+e.getMessageAndLocation();
        //System.err.println(message);
        logger.error("couldn't create transformer object: "+e.getMessageAndLocation());
        logger.error(e.getLocationAsString());  
        return constructErrorXHTMLPage(message);
    } catch (TransformerException e) {
        String message = "TransformerException: " + e.getMessageAndLocation();
        //System.err.println(message);
        logger.error("couldn't transform the source: " + e.getMessage());
        return constructErrorXHTMLPage(message);
    }   
    

    }


    
    public Node transform(File stylesheet, File source) {

    try {
        Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));
        
        DOMResult result = new DOMResult();
        transformer.transform(new StreamSource(source), result);
        return result.getNode().getFirstChild();
    } catch (TransformerConfigurationException e) {
        logger.error("couldn't create transformer object: "+e.getMessageAndLocation());
        logger.error(e.getLocationAsString());  
        String message = "TransformerConfigurationException: "+e.getMessageAndLocation();
        return constructErrorXHTMLPage(message);
    } catch (TransformerException e) {
        logger.error("couldn't transform the source: " + e.getMessage());
        String message = "TransformerException: " + e.getMessageAndLocation();
        return constructErrorXHTMLPage(message);
    }   
    }
    
    
    protected Element constructErrorXHTMLPage(String message) {
        try{
            Document xhtmlDoc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
            // <html></html>
            Node htmlNode = xhtmlDoc.createElement("html");
            xhtmlDoc.appendChild(htmlNode);
            // <head></head>
            Node headNode = xhtmlDoc.createElement("head");
            htmlNode.appendChild(headNode);
            // <title></title>
            Node titleNode = xhtmlDoc.createElement("title");
            headNode.appendChild(titleNode);
            Node titleString = xhtmlDoc.createTextNode("Error occurred");
            titleNode.appendChild(titleString);
            
            // <body></body>
            Node bodyNode = xhtmlDoc.createElement("body");
            htmlNode.appendChild(bodyNode);
            
            // finally put the message in the body
            Node h1Node = xhtmlDoc.createElement("h1");
            bodyNode.appendChild(h1Node);
            Node headingString = xhtmlDoc.createTextNode("The following error occurred:");
            h1Node.appendChild(headingString);
            
            Node textNode = xhtmlDoc.createTextNode(message);
            bodyNode.appendChild(textNode);
            
            return xhtmlDoc.getDocumentElement();
            
        }catch(Exception e) {
            String errmsg = "Exception trying to construct error xhtml page from message: " + message
                + "\n" + e.getMessage();
            System.err.println(errmsg);
            logger.error(errmsg);
            return null;
        }
    }
    
}