src/org/apache/xalan/client/XSLTProcessorApplet.java - xalan-j - Git at Google

 /*
  * The Apache Software License, Version 1.1
  *
  *
  * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. The end-user documentation included with the redistribution,
  *    if any, must include the following acknowledgment:
  *       "This product includes software developed by the
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowledgment may appear in the software itself,
  *    if and wherever such third-party acknowledgments normally appear.
  *
  * 4. The names "Xalan" and "Apache Software Foundation" must
  *    not be used to endorse or promote products derived from this
  *    software without prior written permission. For written
  *    permission, please contact apache@apache.org.
  *
  * 5. Products derived from this software may not be called "Apache",
  *    nor may "Apache" appear in their name, without prior written
  *    permission of the Apache Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  * ====================================================================
  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation and was
  * originally based on software copyright (c) 1999, Lotus
  * Development Corporation., http://www.lotus.com.  For more
  * information on the Apache Software Foundation, please see
  * <http://www.apache.org/>.
  */
 package org.apache.xalan.client;

 import java.applet.Applet;

 import java.awt.Graphics;

 import java.net.URL;
 import java.net.MalformedURLException;

 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.io.StringReader;
 import java.io.IOException;
 import java.io.InputStream;

 import java.util.Properties;

 // Needed Xalan classes
 import org.apache.xalan.res.XSLMessages;
 import org.apache.xalan.res.XSLTErrorResources;

 // Needed TRaX classes
 import javax.xml.transform.Result;
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.TransformerConfigurationException;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.Templates;
 import javax.xml.transform.Source;
 import javax.xml.transform.Result;
 import javax.xml.transform.stream.StreamResult;
 import javax.xml.transform.stream.StreamSource;

 /**
  * <meta name="usage" content="general"/>
  * Provides applet host for the XSLT processor. To perform transformations on an HTML client:
  * <ol>
  * <li>Use an &lt;applet&gt; tag to embed this applet in the HTML client.</li>
  * <li>Use the DocumentURL and StyleURL PARAM tags or the {@link #setDocumentURL} and
  * {@link #setStyleURL} methods to specify the XML source document and XSL stylesheet.</li>
  * <li>Call the {@link #getHtmlText} method (or one of the transformToHtml() methods)
  * to perform the transformation and return the result as a String.</li>
  * </ol>
  */
 public class XSLTProcessorApplet extends Applet
 {

   /**
    * The stylesheet processor.
    * @serial
    */
   TransformerFactory m_tfactory = null;

   /**
    * @serial
    */
   private String m_styleURL;

   /**
    * @serial
    */
   private String m_documentURL;

   // Parameter names.  To change a name of a parameter, you need only make
   // a single change.  Simply modify the value of the parameter string below.
   //--------------------------------------------------------------------------

   /**
    * @serial
    */
   private final String PARAM_styleURL = "styleURL";

   /**
    * @serial
    */
   private final String PARAM_documentURL = "documentURL";


   // We'll keep the DOM trees around, so tell which trees
   // are cached.

   /**
    * @serial
    */
   private String m_styleURLOfCached = null;

   /**
    * @serial
    */
   private String m_documentURLOfCached = null;

   /**
    * Save this for use on the worker thread; may not be necessary.
    * @serial
    */
   private URL m_codeBase = null;

   /**
    * @serial
    */
   private String m_treeURL = null;

   /**
    * DocumentBase URL
    * @serial
    */
   private URL m_documentBase = null;

   /**
    * Thread stuff for the trusted worker thread.
    */
   transient private Thread m_callThread = null;

   /**
    */
   transient private TrustedAgent m_trustedAgent = null;

   /**
    * Thread for running TrustedAgent.
    */
   transient private Thread m_trustedWorker = null;

   /**
    * Where the worker thread puts the HTML text.
    */
   transient private String m_htmlText = null;

   /**
    * Where the worker thread puts the document/stylesheet text.
    */
   transient private String m_sourceText = null;

   /**
    * Stylesheet attribute name and value that the caller can set.
    */
   transient private String m_nameOfIDAttrOfElemToModify = null;

   /**
    */
   transient private String m_elemIdToModify = null;

   /**
    */
   transient private String m_attrNameToSet = null;

   /**
    */
   transient private String m_attrValueToSet = null;

   /**
    * The XSLTProcessorApplet constructor takes no arguments.
    */
   public XSLTProcessorApplet(){}

   /**
    * Get basic information about the applet
    * @return A String with the applet name and author.
    */
   public String getAppletInfo()
   {
     return "Name: XSLTProcessorApplet\r\n" + "Author: Scott Boag";
   }

   /**
    * Get descriptions of the applet parameters.
    * @return A two-dimensional array of Strings with Name, Type, and Description
    * for each parameter.
    */
   public String[][] getParameterInfo()
   {

     String[][] info =
     {
       { PARAM_styleURL, "String", "URL to an XSL stylesheet" },
       { PARAM_documentURL, "String", "URL to an XML document" },
     };

     return info;
   }

   /**
    * Standard applet initialization.
    */
   public void init()
   {

     // PARAMETER SUPPORT
     //          The following code retrieves the value of each parameter
     // specified with the <PARAM> tag and stores it in a member
     // variable.
     //----------------------------------------------------------------------
     String param;

     // styleURL: Parameter description
     //----------------------------------------------------------------------
     param = getParameter(PARAM_styleURL);

     if (param != null)
       setStyleURL(param);

     // documentURL: Parameter description
     //----------------------------------------------------------------------
     param = getParameter(PARAM_documentURL);

     if (param != null)
       setDocumentURL(param);

     m_codeBase = this.getCodeBase();
     m_documentBase = this.getDocumentBase();

     // If you use a ResourceWizard-generated "control creator" class to
     // arrange controls in your applet, you may want to call its
     // CreateControls() method from within this method. Remove the following
     // call to resize() before adding the call to CreateControls();
     // CreateControls() does its own resizing.
     //----------------------------------------------------------------------
     resize(320, 240);
   }

     /**
    *  Automatically called when the HTML client containing the applet loads.
    *  This method starts execution of the applet thread.
    */
   public void start()
   {

     m_trustedAgent = new TrustedAgent();
     Thread currentThread = Thread.currentThread();
     m_trustedWorker = new Thread(currentThread.getThreadGroup(),
                                  m_trustedAgent);
     m_trustedWorker.start();
     try
     {
       m_tfactory = TransformerFactory.newInstance();
       this.showStatus("Causing Transformer and Parser to Load and JIT...");

       // Prime the pump so that subsequent transforms are faster.
       StringReader xmlbuf = new StringReader("<?xml version='1.0'?><foo/>");
       StringReader xslbuf = new StringReader(
         "<?xml version='1.0'?><xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'><xsl:template match='foo'><out/></xsl:template></xsl:stylesheet>");
       PrintWriter pw = new PrintWriter(new StringWriter());

       synchronized (m_tfactory)
       {
         Templates templates = m_tfactory.newTemplates(new StreamSource(xslbuf));
         Transformer transformer = templates.newTransformer();
         transformer.transform(new StreamSource(xmlbuf), new StreamResult(pw));
       }
       System.out.println("Primed the pump!");
       this.showStatus("Ready to go!");
     }
     catch (Exception e)
     {
       this.showStatus("Could not prime the pump!");
       System.out.println("Could not prime the pump!");
       e.printStackTrace();
     }
   }

   /**
    * Do not call; this applet contains no UI or visual components.
    *
    */
   public void paint(Graphics g){}

   /**
    * Automatically called when the HTML page containing the applet is no longer
    * on the screen. Stops execution of the applet thread.
    */
   public void stop()
   {
     if (null != m_trustedWorker)
     {
       m_trustedWorker.stop();

       // m_trustedWorker.destroy();
       m_trustedWorker = null;
     }

     m_styleURLOfCached = null;
     m_documentURLOfCached = null;
   }

   /**
    * Cleanup; called when applet is terminated and unloaded.
    */
   public void destroy()
   {
     if (null != m_trustedWorker)
     {
       m_trustedWorker.stop();

       // m_trustedWorker.destroy();
       m_trustedWorker = null;
     }
     m_styleURLOfCached = null;
     m_documentURLOfCached = null;
   }

   /**
    * Set the URL to the XSL stylesheet that will be used
    * to transform the input XML.  No processing is done yet.
    * @param urlString valid URL string for XSL stylesheet.
    */
   public void setStyleURL(String urlString)
   {
     m_styleURL = urlString;
   }

   /**
    * Set the URL to the XML document that will be transformed
    * with the XSL stylesheet.  No processing is done yet.
    * @param urlString valid URL string for XML document.
    */
   public void setDocumentURL(String urlString)
   {
     m_documentURL = urlString;
   }

   /**
    * The processor keeps a cache of the source and
    * style trees, so call this method if they have changed
    * or you want to do garbage collection.
    */
   public void freeCache()
   {
     m_styleURLOfCached = null;
     m_documentURLOfCached = null;
   }

   /**
    * Set an attribute in the stylesheet, which gives the ability
    * to have some dynamic selection control.
    * @param nameOfIDAttrOfElemToModify The name of an attribute to search for a unique id.
    * @param elemId The unique ID to look for.
    * @param attrName Once the element is found, the name of the attribute to set.
    * @param value The value to set the attribute to.
    */
   public void setStyleSheetAttribute(String nameOfIDAttrOfElemToModify,
                                      String elemId, String attrName,
                                      String value)
   {
     m_nameOfIDAttrOfElemToModify = nameOfIDAttrOfElemToModify;
     m_elemIdToModify = elemId;
     m_attrNameToSet = attrName;
     m_attrValueToSet = value;
   }

   /**
    * Stylesheet parameter key
    */
   transient String m_key;

   /**
    * Stylesheet parameter value
    */
   transient String m_expression;

   /**
    * Submit a stylesheet parameter.
    *
    * @param key stylesheet parameter key
    * @param expr the parameter expression to be submitted.
    * @see javax.xml.transform.Transformer#setParameter(String,Object)
    */
   public void setStylesheetParam(String key, String expr)
   {
     m_key = key;
     m_expression = expr;
   }

   /**
    * Given a String containing markup, escape the markup so it
    * can be displayed in the browser.
    *
    * @param s String to escape
    *
    * The escaped string.
    */
   public String escapeString(String s)
   {
     StringBuffer sb = new StringBuffer();
     int length = s.length();

     for (int i = 0; i < length; i++)
     {
       char ch = s.charAt(i);

       if ('<' == ch)
       {
         sb.append("&lt;");
       }
       else if ('>' == ch)
       {
         sb.append("&gt;");
       }
       else if ('&' == ch)
       {
         sb.append("&amp;");
       }
       else if (0xd800 <= ch && ch < 0xdc00)
       {
         // UTF-16 surrogate
         int next;

         if (i + 1 >= length)
         {
           throw new RuntimeException(
             XSLMessages.createMessage(
               XSLTErrorResources.ER_INVALID_UTF16_SURROGATE,
               new Object[]{ Integer.toHexString(ch) }));  //"Invalid UTF-16 surrogate detected: "

           //+Integer.toHexString(ch)+ " ?");
         }
         else
         {
           next = s.charAt(++i);

           if (!(0xdc00 <= next && next < 0xe000))
             throw new RuntimeException(
               XSLMessages.createMessage(
                 XSLTErrorResources.ER_INVALID_UTF16_SURROGATE,
                 new Object[]{
                   Integer.toHexString(ch) + " "
                   + Integer.toHexString(next) }));  //"Invalid UTF-16 surrogate detected: "

           //+Integer.toHexString(ch)+" "+Integer.toHexString(next));
           next = ((ch - 0xd800) << 10) + next - 0xdc00 + 0x00010000;
         }
         sb.append("&#x");
         sb.append(Integer.toHexString(next));
         sb.append(";");
       }
       else
       {
         sb.append(ch);
       }
     }
     return sb.toString();
   }

   /**
    * Assuming the stylesheet URL and the input XML URL have been set,
    * perform the transformation and return the result as a String.
    *
    * @return A string that contains the contents pointed to by the URL.
    *
    */
   public String getHtmlText()
   {
     m_trustedAgent.m_getData = true;
     m_callThread = Thread.currentThread();
     try
     {
       synchronized (m_callThread)
       {
         m_callThread.wait();
       }
     }
     catch (InterruptedException ie)
     {
       System.out.println(ie.getMessage());
     }
     return m_htmlText;
   }

   /**
    * Get an XML document (or stylesheet)
    *
    * @param treeURL valid URL string for the document.
    *
    * @return document
    *
    * @throws IOException
    */
   public String getTreeAsText(String treeURL) throws IOException
   {
     m_treeURL = treeURL;
     m_trustedAgent.m_getData = true;
     m_trustedAgent.m_getSource = true;
     m_callThread = Thread.currentThread();
     try
     {
       synchronized (m_callThread)
       {
         m_callThread.wait();
       }
     }
     catch (InterruptedException ie)
     {
       System.out.println(ie.getMessage());
     }
     return m_sourceText;
   }

   /**
    * Use a Transformer to copy the source document
    * to a StreamResult.
    *
    * @return the document as a string
    */
   private String getSource() throws TransformerException
   {
     StringWriter osw = new StringWriter();
     PrintWriter pw = new PrintWriter(osw, false);
     String text = "";
     try
     {
       URL docURL = new URL(m_documentBase, m_treeURL);
       synchronized (m_tfactory)
       {
         Transformer transformer = m_tfactory.newTransformer();
         StreamSource source = new StreamSource(docURL.toString());
         StreamResult result = new StreamResult(pw);
         transformer.transform(source, result);
         text = osw.toString();
       }
     }
     catch (MalformedURLException e)
     {
       e.printStackTrace();
       System.exit(-1);
     }
     catch (Exception any_error)
     {
       any_error.printStackTrace();
     }
     return text;
   }

   /**
    * Get the XML source Tree as a text string suitable
    * for display in a browser.  Note that this is for display of the
    * XML itself, not for rendering of HTML by the browser.
    *
    * @return XML source document as a string.
    * @throws Exception thrown if tree can not be converted.
    */
   public String getSourceTreeAsText() throws Exception
   {
     return getTreeAsText(m_documentURL);
   }

   /**
    * Get the XSL style Tree as a text string suitable
    * for display in a browser.  Note that this is for display of the
    * XML itself, not for rendering of HTML by the browser.
    *
    * @return The XSL stylesheet as a string.
    * @throws Exception thrown if tree can not be converted.
    */
   public String getStyleTreeAsText() throws Exception
   {
     return getTreeAsText(m_styleURL);
   }

   /**
    * Get the HTML result Tree as a text string suitable
    * for display in a browser.  Note that this is for display of the
    * XML itself, not for rendering of HTML by the browser.
    *
    * @return Transformation result as unmarked text.
    * @throws Exception thrown if tree can not be converted.
    */
   public String getResultTreeAsText() throws Exception
   {
     return escapeString(getHtmlText());
   }

   /**
    * Process a document and a stylesheet and return
    * the transformation result.  If one of these is null, the
    * existing value (of a previous transformation) is not affected.
    *
    * @param doc URL string to XML document
    * @param style URL string to XSL stylesheet
    *
    * @return HTML transformation result
    */
   public String transformToHtml(String doc, String style)
   {

     if (null != doc)
     {
       m_documentURL = doc;
     }

     if (null != style)
     {
       m_styleURL = style;
     }

     return getHtmlText();
   }

   /**
    * Process a document and a stylesheet and return
    * the transformation result. Use the xsl:stylesheet PI to find the
    * document, if one exists.
    *
    * @param doc  URL string to XML document containing an xsl:stylesheet PI.
    *
    * @return HTML transformation result
    */
   public String transformToHtml(String doc)
   {

     if (null != doc)
     {
       m_documentURL = doc;
     }

     m_styleURL = null;

     return getHtmlText();
   }


   /**
    * Process the transformation.
    *
    * @return The transformation result as a string.
    *
    * @throws TransformerException
    */
   private String processTransformation() throws TransformerException
   {
     String htmlData = null;
     this.showStatus("Waiting for Transformer and Parser to finish loading and JITing...");

     synchronized (m_tfactory)
     {
      URL documentURL = null;
       URL styleURL = null;
       StringWriter osw = new StringWriter();
       PrintWriter pw = new PrintWriter(osw, false);
       StreamResult result = new StreamResult(pw);

       this.showStatus("Begin Transformation...");
       try
       {
         documentURL = new URL(m_codeBase, m_documentURL);
         StreamSource xmlSource = new StreamSource(documentURL.toString());

         styleURL = new URL(m_codeBase, m_styleURL);
         StreamSource xslSource = new StreamSource(styleURL.toString());

         Transformer transformer = m_tfactory.newTransformer(xslSource);

         if (null != m_key)
           transformer.setParameter(m_key, m_expression);

          transformer.transform(xmlSource, result);
       }
       catch (TransformerConfigurationException tfe)
       {
         tfe.printStackTrace();
         System.exit(-1);
       }
       catch (MalformedURLException e)
       {
         e.printStackTrace();
         System.exit(-1);
       }

       this.showStatus("Transformation Done!");
       htmlData = osw.toString();
     }
     return htmlData;
   }

   /**
    * This class maintains a worker thread that that is
    * trusted and can do things like access data.  You need
    * this because the thread that is called by the browser
    * is not trusted and can't access data from the URLs.
    */
   class TrustedAgent implements Runnable
   {

     /**
      * Specifies whether the worker thread should perform a transformation.
      */
     public boolean m_getData = false;

     /**
      * Specifies whether the worker thread should get an XML document or XSL stylesheet.
      */
     public boolean m_getSource = false;

     /**
      * The real work is done from here.
      *
      */
     public void run()
     {
       while (true)
       {
         m_trustedWorker.yield();

         if (m_getData)  // Perform a transformation or get a document.
         {
           try
           {
             m_getData = false;
             m_htmlText = null;
             m_sourceText = null;
             if (m_getSource)  // Get a document.
             {
               m_getSource = false;
               m_sourceText = getSource();
             }
             else              // Perform a transformation.
               m_htmlText = processTransformation();
           }
           catch (Exception e)
           {
             e.printStackTrace();
           }
           finally
           {
             synchronized (m_callThread)
             {
               m_callThread.notify();
             }
           }
         }
         else
         {
           try
           {
             m_trustedWorker.sleep(50);
           }
           catch (InterruptedException ie)
           {
             ie.printStackTrace();
           }
         }
       }
     }
   }
 }
	/*
	* The Apache Software License, Version 1.1
	*
	*
	* Copyright (c) 1999-2003 The Apache Software Foundation. All rights
	* reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. The end-user documentation included with the redistribution,
	* if any, must include the following acknowledgment:
	* "This product includes software developed by the
	* Apache Software Foundation (http://www.apache.org/)."
	* Alternately, this acknowledgment may appear in the software itself,
	* if and wherever such third-party acknowledgments normally appear.
	*
	* 4. The names "Xalan" and "Apache Software Foundation" must
	* not be used to endorse or promote products derived from this
	* software without prior written permission. For written
	* permission, please contact apache@apache.org.
	*
	* 5. Products derived from this software may not be called "Apache",
	* nor may "Apache" appear in their name, without prior written
	* permission of the Apache Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	* ====================================================================
	*
	* This software consists of voluntary contributions made by many
	* individuals on behalf of the Apache Software Foundation and was
	* originally based on software copyright (c) 1999, Lotus
	* Development Corporation., http://www.lotus.com. For more
	* information on the Apache Software Foundation, please see
	* <http://www.apache.org/>.
	*/
	package org.apache.xalan.client;

	import java.applet.Applet;

	import java.awt.Graphics;

	import java.net.URL;
	import java.net.MalformedURLException;

	import java.io.PrintWriter;
	import java.io.StringWriter;
	import java.io.StringReader;
	import java.io.IOException;
	import java.io.InputStream;

	import java.util.Properties;

	// Needed Xalan classes
	import org.apache.xalan.res.XSLMessages;
	import org.apache.xalan.res.XSLTErrorResources;

	// Needed TRaX classes
	import javax.xml.transform.Result;
	import javax.xml.transform.TransformerFactory;
	import javax.xml.transform.TransformerConfigurationException;
	import javax.xml.transform.Transformer;
	import javax.xml.transform.TransformerException;
	import javax.xml.transform.Templates;
	import javax.xml.transform.Source;
	import javax.xml.transform.Result;
	import javax.xml.transform.stream.StreamResult;
	import javax.xml.transform.stream.StreamSource;

	/**
	* <meta name="usage" content="general"/>
	* Provides applet host for the XSLT processor. To perform transformations on an HTML client:
	* <ol>
	* <li>Use an <applet> tag to embed this applet in the HTML client.</li>
	* <li>Use the DocumentURL and StyleURL PARAM tags or the {@link #setDocumentURL} and
	* {@link #setStyleURL} methods to specify the XML source document and XSL stylesheet.</li>
	* <li>Call the {@link #getHtmlText} method (or one of the transformToHtml() methods)
	* to perform the transformation and return the result as a String.</li>
	* </ol>
	*/
	public class XSLTProcessorApplet extends Applet
	{

	/**
	* The stylesheet processor.
	* @serial
	*/
	TransformerFactory m_tfactory = null;

	/**
	* @serial
	*/
	private String m_styleURL;

	/**
	* @serial
	*/
	private String m_documentURL;

	// Parameter names. To change a name of a parameter, you need only make
	// a single change. Simply modify the value of the parameter string below.
	//--------------------------------------------------------------------------

	/**
	* @serial
	*/
	private final String PARAM_styleURL = "styleURL";

	/**
	* @serial
	*/
	private final String PARAM_documentURL = "documentURL";


	// We'll keep the DOM trees around, so tell which trees
	// are cached.

	/**
	* @serial
	*/
	private String m_styleURLOfCached = null;

	/**
	* @serial
	*/
	private String m_documentURLOfCached = null;

	/**
	* Save this for use on the worker thread; may not be necessary.
	* @serial
	*/
	private URL m_codeBase = null;

	/**
	* @serial
	*/
	private String m_treeURL = null;

	/**
	* DocumentBase URL
	* @serial
	*/
	private URL m_documentBase = null;

	/**
	* Thread stuff for the trusted worker thread.
	*/
	transient private Thread m_callThread = null;

	/**
	*/
	transient private TrustedAgent m_trustedAgent = null;

	/**
	* Thread for running TrustedAgent.
	*/
	transient private Thread m_trustedWorker = null;

	/**
	* Where the worker thread puts the HTML text.
	*/
	transient private String m_htmlText = null;

	/**
	* Where the worker thread puts the document/stylesheet text.
	*/
	transient private String m_sourceText = null;

	/**
	* Stylesheet attribute name and value that the caller can set.
	*/
	transient private String m_nameOfIDAttrOfElemToModify = null;

	/**
	*/
	transient private String m_elemIdToModify = null;

	/**
	*/
	transient private String m_attrNameToSet = null;

	/**
	*/
	transient private String m_attrValueToSet = null;

	/**
	* The XSLTProcessorApplet constructor takes no arguments.
	*/
	public XSLTProcessorApplet(){}

	/**
	* Get basic information about the applet
	* @return A String with the applet name and author.
	*/
	public String getAppletInfo()
	{
	return "Name: XSLTProcessorApplet\r\n" + "Author: Scott Boag";
	}

	/**
	* Get descriptions of the applet parameters.
	* @return A two-dimensional array of Strings with Name, Type, and Description
	* for each parameter.
	*/
	public String[][] getParameterInfo()
	{

	String[][] info =
	{
	{ PARAM_styleURL, "String", "URL to an XSL stylesheet" },
	{ PARAM_documentURL, "String", "URL to an XML document" },
	};

	return info;
	}

	/**
	* Standard applet initialization.
	*/
	public void init()
	{

	// PARAMETER SUPPORT
	// The following code retrieves the value of each parameter
	// specified with the <PARAM> tag and stores it in a member
	// variable.
	//----------------------------------------------------------------------
	String param;

	// styleURL: Parameter description
	//----------------------------------------------------------------------
	param = getParameter(PARAM_styleURL);

	if (param != null)
	setStyleURL(param);

	// documentURL: Parameter description
	//----------------------------------------------------------------------
	param = getParameter(PARAM_documentURL);

	if (param != null)
	setDocumentURL(param);

	m_codeBase = this.getCodeBase();
	m_documentBase = this.getDocumentBase();

	// If you use a ResourceWizard-generated "control creator" class to
	// arrange controls in your applet, you may want to call its
	// CreateControls() method from within this method. Remove the following
	// call to resize() before adding the call to CreateControls();
	// CreateControls() does its own resizing.
	//----------------------------------------------------------------------
	resize(320, 240);
	}

	/**
	* Automatically called when the HTML client containing the applet loads.
	* This method starts execution of the applet thread.
	*/
	public void start()
	{

	m_trustedAgent = new TrustedAgent();
	Thread currentThread = Thread.currentThread();
	m_trustedWorker = new Thread(currentThread.getThreadGroup(),
	m_trustedAgent);
	m_trustedWorker.start();
	try
	{
	m_tfactory = TransformerFactory.newInstance();
	this.showStatus("Causing Transformer and Parser to Load and JIT...");

	// Prime the pump so that subsequent transforms are faster.
	StringReader xmlbuf = new StringReader("<?xml version='1.0'?><foo/>");
	StringReader xslbuf = new StringReader(
	"<?xml version='1.0'?><xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'><xsl:template match='foo'><out/></xsl:template></xsl:stylesheet>");
	PrintWriter pw = new PrintWriter(new StringWriter());

	synchronized (m_tfactory)
	{
	Templates templates = m_tfactory.newTemplates(new StreamSource(xslbuf));
	Transformer transformer = templates.newTransformer();
	transformer.transform(new StreamSource(xmlbuf), new StreamResult(pw));
	}
	System.out.println("Primed the pump!");
	this.showStatus("Ready to go!");
	}
	catch (Exception e)
	{
	this.showStatus("Could not prime the pump!");
	System.out.println("Could not prime the pump!");
	e.printStackTrace();
	}
	}

	/**
	* Do not call; this applet contains no UI or visual components.
	*
	*/
	public void paint(Graphics g){}

	/**
	* Automatically called when the HTML page containing the applet is no longer
	* on the screen. Stops execution of the applet thread.
	*/
	public void stop()
	{
	if (null != m_trustedWorker)
	{
	m_trustedWorker.stop();

	// m_trustedWorker.destroy();
	m_trustedWorker = null;
	}

	m_styleURLOfCached = null;
	m_documentURLOfCached = null;
	}

	/**
	* Cleanup; called when applet is terminated and unloaded.
	*/
	public void destroy()
	{
	if (null != m_trustedWorker)
	{
	m_trustedWorker.stop();

	// m_trustedWorker.destroy();
	m_trustedWorker = null;
	}
	m_styleURLOfCached = null;
	m_documentURLOfCached = null;
	}

	/**
	* Set the URL to the XSL stylesheet that will be used
	* to transform the input XML. No processing is done yet.
	* @param urlString valid URL string for XSL stylesheet.
	*/
	public void setStyleURL(String urlString)
	{
	m_styleURL = urlString;
	}

	/**
	* Set the URL to the XML document that will be transformed
	* with the XSL stylesheet. No processing is done yet.
	* @param urlString valid URL string for XML document.
	*/
	public void setDocumentURL(String urlString)
	{
	m_documentURL = urlString;
	}

	/**
	* The processor keeps a cache of the source and
	* style trees, so call this method if they have changed
	* or you want to do garbage collection.
	*/
	public void freeCache()
	{
	m_styleURLOfCached = null;
	m_documentURLOfCached = null;
	}

	/**
	* Set an attribute in the stylesheet, which gives the ability
	* to have some dynamic selection control.
	* @param nameOfIDAttrOfElemToModify The name of an attribute to search for a unique id.
	* @param elemId The unique ID to look for.
	* @param attrName Once the element is found, the name of the attribute to set.
	* @param value The value to set the attribute to.
	*/
	public void setStyleSheetAttribute(String nameOfIDAttrOfElemToModify,
	String elemId, String attrName,
	String value)
	{
	m_nameOfIDAttrOfElemToModify = nameOfIDAttrOfElemToModify;
	m_elemIdToModify = elemId;
	m_attrNameToSet = attrName;
	m_attrValueToSet = value;
	}

	/**
	* Stylesheet parameter key
	*/
	transient String m_key;

	/**
	* Stylesheet parameter value
	*/
	transient String m_expression;

	/**
	* Submit a stylesheet parameter.
	*
	* @param key stylesheet parameter key
	* @param expr the parameter expression to be submitted.
	* @see javax.xml.transform.Transformer#setParameter(String,Object)
	*/
	public void setStylesheetParam(String key, String expr)
	{
	m_key = key;
	m_expression = expr;
	}

	/**
	* Given a String containing markup, escape the markup so it
	* can be displayed in the browser.
	*
	* @param s String to escape
	*
	* The escaped string.
	*/
	public String escapeString(String s)
	{
	StringBuffer sb = new StringBuffer();
	int length = s.length();

	for (int i = 0; i < length; i++)
	{
	char ch = s.charAt(i);

	if ('<' == ch)
	{
	sb.append("<");
	}
	else if ('>' == ch)
	{
	sb.append(">");
	}
	else if ('&' == ch)
	{
	sb.append("&");
	}
	else if (0xd800 <= ch && ch < 0xdc00)
	{
	// UTF-16 surrogate
	int next;

	if (i + 1 >= length)
	{
	throw new RuntimeException(
	XSLMessages.createMessage(
	XSLTErrorResources.ER_INVALID_UTF16_SURROGATE,
	new Object[]{ Integer.toHexString(ch) })); //"Invalid UTF-16 surrogate detected: "

	//+Integer.toHexString(ch)+ " ?");
	}
	else
	{
	next = s.charAt(++i);

	if (!(0xdc00 <= next && next < 0xe000))
	throw new RuntimeException(
	XSLMessages.createMessage(
	XSLTErrorResources.ER_INVALID_UTF16_SURROGATE,
	new Object[]{
	Integer.toHexString(ch) + " "
	+ Integer.toHexString(next) })); //"Invalid UTF-16 surrogate detected: "

	//+Integer.toHexString(ch)+" "+Integer.toHexString(next));
	next = ((ch - 0xd800) << 10) + next - 0xdc00 + 0x00010000;
	}
	sb.append("&#x");
	sb.append(Integer.toHexString(next));
	sb.append(";");
	}
	else
	{
	sb.append(ch);
	}
	}
	return sb.toString();
	}

	/**
	* Assuming the stylesheet URL and the input XML URL have been set,
	* perform the transformation and return the result as a String.
	*
	* @return A string that contains the contents pointed to by the URL.
	*
	*/
	public String getHtmlText()
	{
	m_trustedAgent.m_getData = true;
	m_callThread = Thread.currentThread();
	try
	{
	synchronized (m_callThread)
	{
	m_callThread.wait();
	}
	}
	catch (InterruptedException ie)
	{
	System.out.println(ie.getMessage());
	}
	return m_htmlText;
	}

	/**
	* Get an XML document (or stylesheet)
	*
	* @param treeURL valid URL string for the document.
	*
	* @return document
	*
	* @throws IOException
	*/
	public String getTreeAsText(String treeURL) throws IOException
	{
	m_treeURL = treeURL;
	m_trustedAgent.m_getData = true;
	m_trustedAgent.m_getSource = true;
	m_callThread = Thread.currentThread();
	try
	{
	synchronized (m_callThread)
	{
	m_callThread.wait();
	}
	}
	catch (InterruptedException ie)
	{
	System.out.println(ie.getMessage());
	}
	return m_sourceText;
	}

	/**
	* Use a Transformer to copy the source document
	* to a StreamResult.
	*
	* @return the document as a string
	*/
	private String getSource() throws TransformerException
	{
	StringWriter osw = new StringWriter();
	PrintWriter pw = new PrintWriter(osw, false);
	String text = "";
	try
	{
	URL docURL = new URL(m_documentBase, m_treeURL);
	synchronized (m_tfactory)
	{
	Transformer transformer = m_tfactory.newTransformer();
	StreamSource source = new StreamSource(docURL.toString());
	StreamResult result = new StreamResult(pw);
	transformer.transform(source, result);
	text = osw.toString();
	}
	}
	catch (MalformedURLException e)
	{
	e.printStackTrace();
	System.exit(-1);
	}
	catch (Exception any_error)
	{
	any_error.printStackTrace();
	}
	return text;
	}

	/**
	* Get the XML source Tree as a text string suitable
	* for display in a browser. Note that this is for display of the
	* XML itself, not for rendering of HTML by the browser.
	*
	* @return XML source document as a string.
	* @throws Exception thrown if tree can not be converted.
	*/
	public String getSourceTreeAsText() throws Exception
	{
	return getTreeAsText(m_documentURL);
	}

	/**
	* Get the XSL style Tree as a text string suitable
	* for display in a browser. Note that this is for display of the
	* XML itself, not for rendering of HTML by the browser.
	*
	* @return The XSL stylesheet as a string.
	* @throws Exception thrown if tree can not be converted.
	*/
	public String getStyleTreeAsText() throws Exception
	{
	return getTreeAsText(m_styleURL);
	}

	/**
	* Get the HTML result Tree as a text string suitable
	* for display in a browser. Note that this is for display of the
	* XML itself, not for rendering of HTML by the browser.
	*
	* @return Transformation result as unmarked text.
	* @throws Exception thrown if tree can not be converted.
	*/
	public String getResultTreeAsText() throws Exception
	{
	return escapeString(getHtmlText());
	}

	/**
	* Process a document and a stylesheet and return
	* the transformation result. If one of these is null, the
	* existing value (of a previous transformation) is not affected.
	*
	* @param doc URL string to XML document
	* @param style URL string to XSL stylesheet
	*
	* @return HTML transformation result
	*/
	public String transformToHtml(String doc, String style)
	{

	if (null != doc)
	{
	m_documentURL = doc;
	}

	if (null != style)
	{
	m_styleURL = style;
	}

	return getHtmlText();
	}

	/**
	* Process a document and a stylesheet and return
	* the transformation result. Use the xsl:stylesheet PI to find the
	* document, if one exists.
	*
	* @param doc URL string to XML document containing an xsl:stylesheet PI.
	*
	* @return HTML transformation result
	*/
	public String transformToHtml(String doc)
	{

	if (null != doc)
	{
	m_documentURL = doc;
	}

	m_styleURL = null;

	return getHtmlText();
	}


	/**
	* Process the transformation.
	*
	* @return The transformation result as a string.
	*
	* @throws TransformerException
	*/
	private String processTransformation() throws TransformerException
	{
	String htmlData = null;
	this.showStatus("Waiting for Transformer and Parser to finish loading and JITing...");

	synchronized (m_tfactory)
	{
	URL documentURL = null;
	URL styleURL = null;
	StringWriter osw = new StringWriter();
	PrintWriter pw = new PrintWriter(osw, false);
	StreamResult result = new StreamResult(pw);

	this.showStatus("Begin Transformation...");
	try
	{
	documentURL = new URL(m_codeBase, m_documentURL);
	StreamSource xmlSource = new StreamSource(documentURL.toString());

	styleURL = new URL(m_codeBase, m_styleURL);
	StreamSource xslSource = new StreamSource(styleURL.toString());

	Transformer transformer = m_tfactory.newTransformer(xslSource);

	if (null != m_key)
	transformer.setParameter(m_key, m_expression);

	transformer.transform(xmlSource, result);
	}
	catch (TransformerConfigurationException tfe)
	{
	tfe.printStackTrace();
	System.exit(-1);
	}
	catch (MalformedURLException e)
	{
	e.printStackTrace();
	System.exit(-1);
	}

	this.showStatus("Transformation Done!");
	htmlData = osw.toString();
	}
	return htmlData;
	}

	/**
	* This class maintains a worker thread that that is
	* trusted and can do things like access data. You need
	* this because the thread that is called by the browser
	* is not trusted and can't access data from the URLs.
	*/
	class TrustedAgent implements Runnable
	{

	/**
	* Specifies whether the worker thread should perform a transformation.
	*/
	public boolean m_getData = false;

	/**
	* Specifies whether the worker thread should get an XML document or XSL stylesheet.
	*/
	public boolean m_getSource = false;

	/**
	* The real work is done from here.
	*
	*/
	public void run()
	{
	while (true)
	{
	m_trustedWorker.yield();

	if (m_getData) // Perform a transformation or get a document.
	{
	try
	{
	m_getData = false;
	m_htmlText = null;
	m_sourceText = null;
	if (m_getSource) // Get a document.
	{
	m_getSource = false;
	m_sourceText = getSource();
	}
	else // Perform a transformation.
	m_htmlText = processTransformation();
	}
	catch (Exception e)
	{
	e.printStackTrace();
	}
	finally
	{
	synchronized (m_callThread)
	{
	m_callThread.notify();
	}
	}
	}
	else
	{
	try
	{
	m_trustedWorker.sleep(50);
	}
	catch (InterruptedException ie)
	{
	ie.printStackTrace();
	}
	}
	}
	}
	}
	}