Jetty example source code file (TagLibConfiguration.java)

This example Jetty source code file (TagLibConfiguration.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Jetty tags/keywords

could, exception, exception, iterator, jar, jarfile, net, network, regex, resource, resource, set, string, string, tld, tld, util, webappcontext, xmlparser, zip

The Jetty TagLibConfiguration.java source code

//========================================================================
//$Id: TagLibConfiguration.java,v 1.4 2005/08/13 00:01:27 gregwilkins Exp $
//Copyright 2004 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//Licensed 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.
//========================================================================

package org.mortbay.jetty.webapp;

import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.EventListener;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.jar.JarFile;
import java.util.regex.Pattern;
import java.util.zip.ZipEntry;

import org.mortbay.log.Log;
import org.mortbay.resource.Resource;
import org.mortbay.util.Loader;
import org.mortbay.xml.XmlParser;

/* ------------------------------------------------------------ */
/** TagLibConfiguration.
 * 
 * The class searches for TLD descriptors found in web.xml, in WEB-INF/*.tld files of the web app
 * or *.tld files withing jars found in WEB-INF/lib of the webapp.   Any listeners defined in these
 * tld's are added to the context.
 * 
 * <bile>This is total rubbish special case for JSPs! If there was a general use-case for web app
 * frameworks to register listeners directly, then a generic mechanism could have been added to the servlet
 * spec.  Instead some special purpose JSP support is required that breaks all sorts of encapsualtion rules as
 * the servlet container must go searching for and then parsing the descriptors for one particular framework.
 * It only appears to be used by JSF, which is being developed by the same developer who implemented this
 * feature in the first place!
 * </bile>
 * 
 * @author gregw
 *
 */
public class TagLibConfiguration implements Configuration
{
    WebAppContext _context;
    
    /* ------------------------------------------------------------ */
    public void setWebAppContext(WebAppContext context)
    {
        _context=context;
    }

    /* ------------------------------------------------------------ */
    public WebAppContext getWebAppContext()
    {
        return _context;
    }

    /* ------------------------------------------------------------ */
    public void configureClassLoader() throws Exception
    {
    }

    /* ------------------------------------------------------------ */
    /* 
     * @see org.mortbay.jetty.servlet.WebAppContext.Configuration#configureDefaults()
     */
    public void configureDefaults() throws Exception
    {
    }

    
    /* ------------------------------------------------------------ */
    /* 
     * @see org.mortbay.jetty.servlet.WebAppContext.Configuration#configureWebApp()
     */
    public void configureWebApp() throws Exception
    {   
        Set tlds = new HashSet();
        Set jars = new HashSet();
        
        // Find tld's from web.xml
        // When the XMLConfigurator (or other configurator) parsed the web.xml,
        // It should have created aliases for all TLDs.  So search resources aliases
        // for aliases ending in tld
        if (_context.getResourceAliases()!=null && 
            _context.getBaseResource()!=null && 
            _context.getBaseResource().exists())
        {
            Iterator iter=_context.getResourceAliases().values().iterator();
            while(iter.hasNext())
            {
                String location = (String)iter.next();
                if (location!=null && location.toLowerCase().endsWith(".tld"))
                {
                    if (!location.startsWith("/"))
                        location="/WEB-INF/"+location;
                    Resource l=_context.getBaseResource().addPath(location);
                    tlds.add(l);
                }
            }
        }
        
        // Look for any tlds in WEB-INF directly.
        Resource web_inf = _context.getWebInf();
        if (web_inf!=null)
        {
            String[] contents = web_inf.list();
            for (int i=0;contents!=null && i<contents.length;i++)
            {
                if (contents[i]!=null && contents[i].toLowerCase().endsWith(".tld"))
                {
                    Resource l=_context.getWebInf().addPath(contents[i]);
                    tlds.add(l);
                }
                
            }
        }
        
        // Get the pattern for noTLDJars
        String no_TLD_attr = _context.getInitParameter("org.mortbay.jetty.webapp.NoTLDJarPattern");
        Pattern no_TLD_pattern = no_TLD_attr==null?null:Pattern.compile(no_TLD_attr);
        
        // Look for tlds in any jars
 
        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        boolean parent=false;
        
        while (loader!=null)
        {
            if (loader instanceof URLClassLoader)
            {
                URL[] urls = ((URLClassLoader)loader).getURLs();

                if (urls!=null)
                {
                    for (int i=0;i<urls.length;i++)
                    {   
                        if (urls[i].toString().toLowerCase().endsWith(".jar"))
                        {

                            String jar = urls[i].toString();
                            int slash=jar.lastIndexOf('/');
                            jar=jar.substring(slash+1);

                            if (parent && ( 
                                    (!_context.isParentLoaderPriority() && jars.contains(jar)) || 
                                    (no_TLD_pattern!=null && no_TLD_pattern.matcher(jar).matches())))
                                continue;
                            jars.add(jar);
                            
                            Log.debug("TLD search of {}",urls[i]);
                            
                            File file=Resource.newResource(urls[i]).getFile();
                            if (file==null || !file.exists() || !file.canRead())
                                continue;
                            
                            JarFile jarfile = new JarFile(file);
                            try
                            {
                                Enumeration e = jarfile.entries();
                                while (e.hasMoreElements())
                                {
                                    ZipEntry entry = (ZipEntry)e.nextElement();
                                    String name = entry.getName();
                                    if (name.startsWith("META-INF/") && name.toLowerCase().endsWith(".tld"))
                                    {
                                        Resource tld=Resource.newResource("jar:"+urls[i]+"!/"+name);
                                        tlds.add(tld);
                                        Log.debug("TLD found {}",tld);
                                    }
                                }
                            }
                            finally
                            {
                                jarfile.close();
                            }   
                        }
                    }
                }
            }

            loader=loader.getParent();
            parent=true;
            
        }
        
        // Create a TLD parser
        XmlParser parser = new XmlParser(false);
        parser.redirectEntity("web-jsptaglib_1_1.dtd",Loader.getResource(TagLibConfiguration.class,"javax/servlet/jsp/resources/web-jsptaglibrary_1_1.dtd", false));
        parser.redirectEntity("web-jsptaglib_1_2.dtd",Loader.getResource(TagLibConfiguration.class,"javax/servlet/jsp/resources/web-jsptaglibrary_1_2.dtd", false));
        parser.redirectEntity("web-jsptaglib_2_0.xsd",Loader.getResource(TagLibConfiguration.class,"javax/servlet/jsp/resources/web-jsptaglibrary_2_0.xsd", false));
        parser.redirectEntity("web-jsptaglibrary_1_1.dtd",Loader.getResource(TagLibConfiguration.class,"javax/servlet/jsp/resources/web-jsptaglibrary_1_1.dtd", false));
        parser.redirectEntity("web-jsptaglibrary_1_2.dtd",Loader.getResource(TagLibConfiguration.class,"javax/servlet/jsp/resources/web-jsptaglibrary_1_2.dtd", false));
        parser.redirectEntity("web-jsptaglibrary_2_0.xsd",Loader.getResource(TagLibConfiguration.class,"javax/servlet/jsp/resources/web-jsptaglibrary_2_0.xsd", false));
        parser.setXpath("/taglib/listener/listener-class");
        // Parse all the discovered TLDs
        Iterator iter = tlds.iterator();
        while (iter.hasNext())
        {
            try
            {
                Resource tld = (Resource)iter.next();
                if (Log.isDebugEnabled()) Log.debug("TLD="+tld);
                
                XmlParser.Node root;
                
                try
                {
                    //xerces on apple appears to sometimes close the zip file instead
                    //of the inputstream, so try opening the input stream, but if
                    //that doesn't work, fallback to opening a new url
                    root = parser.parse(tld.getInputStream());
                }
                catch (Exception e)
                {
                    root = parser.parse(tld.getURL().toString());
                }

		if (root==null)
		{
		    Log.warn("No TLD root in {}",tld);
		    continue;
		}
                
                for (int i=0;i<root.size();i++)
                {
                    Object o=root.get(i);
                    if (o instanceof XmlParser.Node)
                    {
                        XmlParser.Node node = (XmlParser.Node)o;
                        if ("listener".equals(node.getTag()))
                        {
                            String className=node.getString("listener-class",false,true);
                            if (Log.isDebugEnabled()) Log.debug("listener="+className);
                            
                            try
                            {
                                Class listenerClass=getWebAppContext().loadClass(className);
                                EventListener l=(EventListener)listenerClass.newInstance();
                                _context.addEventListener(l);
                            }
                            catch(Exception e)
                            {
                                Log.warn("Could not instantiate listener "+className+": "+e);
                                Log.debug(e);
                            }
                            catch(Error e)
                            {
                                Log.warn("Could not instantiate listener "+className+": "+e);
                                Log.debug(e);
                            }
                        }
                    }
                }
            }
            catch(Exception e)
            {
                Log.warn(e);
            }
        }
    }


    public void deconfigureWebApp() throws Exception
    {
    }
    

}