code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.StringWriter;
  
  import java.util.StringTokenizer;
  
  import javax.xml.transform.Transformer;
  import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.TransformerException;
  import javax.xml.transform.ErrorListener;
  import javax.xml.transform.stream.StreamResult;
  import javax.xml.transform.stream.StreamSource;
  
  import sunlabs.brazil.server.Handler;
  import sunlabs.brazil.server.Request;
  import sunlabs.brazil.server.Server;
  
  /**
   * This Brazil handler demonstrates how XSL transformations can be made
   * available as a web service without using a full web server. This class
   * implements the Handler interface from the Brazil project, see:
   * http://www.sun.com/research/brazil/
   *
   * Note that the XSLTC transformation engine is invoked through the JAXP
   * interface, using the XSLTC "use-classpath" attribute.  The
   * "use-from-classpath" attribute specifies to the XSLTC TransformerFactory
   * that a precompiled version of the stylesheet (translet) may be available,
   * and that should be used in preference to recompiling the stylesheet.
   * @author Morten Jorgensen
   */
  public class TransformHandler implements Handler {
  
      private TransformerFactory m_tf = null;
  
      // These two are used while parsing the parameters in the URL
      private final String PARAM_TRANSLET = "translet=";
      private final String PARAM_DOCUMENT = "document=";
      private final String PARAM_STATS = "stats=";
  
      // All output goes here:
      private PrintWriter m_out = null;
  
      /**
       * Dump an error message to output
       */
      public void errorMessage(String message, Exception e) {
  	if (m_out == null) {
              return;
          }
  	m_out.println("<h1>XSL transformation error</h1>"+message);
  	m_out.println("<br>Exception:</br>"+e.toString());
      }
  
      public void errorMessage(String message) {
  	if (m_out == null) return;
  	m_out.println("<h1>XSL transformation error</h1>"+message);
      }
  
      /**
       * This method is run when the Brazil proxy is loaded
       */
      public boolean init(Server server, String prefix) {
  	return true;
      }
  
      /**
       * This method is run for every HTTP request sent to the proxy
       */
      public boolean respond(Request request) throws IOException {
  
  	// Initialise the output buffer
  	final StringWriter sout = new StringWriter();
  	m_out = new PrintWriter(sout);
  
  	// These two hold the parameters from the URL 'translet' and 'document'
  	String transletName = null;
  	String document = null;
  	String stats = null;
  
  	// Get the parameters from the URL
  	final StringTokenizer params = new StringTokenizer(request.query,"&");
  	while (params.hasMoreElements()) {
  	    final String param = params.nextToken();
  	    if (param.startsWith(PARAM_TRANSLET)) {
  		transletName = param.substring(PARAM_TRANSLET.length());
  	    }
  	    else if (param.startsWith(PARAM_DOCUMENT)) {
  		document = param.substring(PARAM_DOCUMENT.length());
  	    }
  	    else if (param.startsWith(PARAM_STATS)) {
  		stats = param.substring(PARAM_STATS.length());
  	    }
  	}
  
  	try {
  	    // Make sure that both parameters were specified
  	    if ((transletName == null) || (document == null)) {
  		errorMessage("Parameters <b><tt>translet</tt></b> and/or "+
  			     "<b><tt>document</tt></b> not specified.");
  	    }
  	    else {
                  if (m_tf == null) {
                      m_tf = TransformerFactory.newInstance();
                      try {
                          m_tf.setAttribute("use-classpath", Boolean.TRUE);
                      } catch (IllegalArgumentException iae) {
                          System.err.println(
                              "Could not set XSLTC-specific TransformerFactory "
                            + "attributes.  Transformation failed.");
                      }
                  }
                  Transformer t =
                       m_tf.newTransformer(new StreamSource(transletName));
  
  		// Do the actual transformation
  		final long start = System.currentTimeMillis();
  		t.transform(new StreamSource(document),
                              new StreamResult(m_out));
  		final long done = System.currentTimeMillis() - start;
  		m_out.println("<!-- transformed by XSLTC in "+done+"ms -->");
  	    }
  	}
  	catch (Exception e) {
  	    errorMessage("Internal error.",e);
  	}
  
  	// Pass the transformation output as the HTTP response
  	request.sendResponse(sout.toString());
  	return true;
      }
  
  
  }
  