PluggableWebAppRegistrationCustomizerImpl.java

// ========================================================================
// Copyright (c) 2009-2010 Intalio, Inc.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
// The Eclipse Public License is available at 
// http://www.eclipse.org/legal/epl-v10.html
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
// You may elect to redistribute this code under either of these licenses. 
// ========================================================================
package org.eclipse.jetty.osgi.boot.jasper;

import java.io.File;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.StringTokenizer;

import org.eclipse.jetty.osgi.boot.OSGiAppProvider;
import org.eclipse.jetty.osgi.boot.utils.BundleFileLocatorHelper;
import org.eclipse.jetty.osgi.boot.utils.WebappRegistrationCustomizer;
import org.osgi.framework.Bundle;
import org.osgi.framework.FrameworkUtil;

/**
 * Plug bundles that contains tld files so that jasper will discover them
 * and set them up in jetty.
 * 
 * For example: -Dorg.eclipse.jetty.osgi.tldbundles=org.springframework.web.servlet,com.opensymphony.module.sitemesh
 * Otherwise use an attribute to the WebAppDeployer
 * <New class="org.eclipse.jetty.deploy.providers.WebAppProvider">
 * ....
 *   <Set name="tldBundles"><Property name="org.eclipse.jetty.osgi.tldsbundles" default="" /></Set>
 * <New>
 */
public class PluggableWebAppRegistrationCustomizerImpl implements WebappRegistrationCustomizer
{
	/**
	 * To plug into jasper bundles that contain tld files
	 * please use a list of bundle's symbolic names:
	 *  -Djetty.osgi.tldbundles=org.springframework.web.servlet,com.opensymphony.module.sitemesh
	 */
	public static final String SYS_PROP_TLD_BUNDLES = "org.eclipse.jetty.osgi.tldbundles";
    
	/**
	 * Union of the tld bundles defined system wide and the one defines as an attribute of the AppProvider.
	 * @param provider
	 * @return
	 */
	private static Collection<String> getTldBundles(OSGiAppProvider provider)
	{
		String sysprop = System.getProperty(SYS_PROP_TLD_BUNDLES);
		String att = (String)provider.getTldBundles();
		if (sysprop == null && att == null)
		{
			return Collections.emptySet();
		}
		if (att == null)
		{
			att = sysprop;
		}
		else if (sysprop != null)
		{
			att = att + "," + sysprop;
		}
			
		Collection<String> tldbundles = new HashSet<String>();
		StringTokenizer tokenizer = new StringTokenizer(att, ", \n\r\t", false);
		while (tokenizer.hasMoreTokens())
		{
			tldbundles.add(tokenizer.nextToken());
		}
		return tldbundles;
	}
	
	/**
	 * @return The location of the jars that contain tld files.
	 * Jasper will discover them.
	 */
    public URL[] getJarsWithTlds(OSGiAppProvider provider, BundleFileLocatorHelper locatorHelper) throws Exception
    {
    	List<URL> urls = new ArrayList<URL>();
    	//naive way of finding those bundles.
    	//lots of assumptions: for example we assume a single version of each bundle that would contain tld files.
    	//this is probably good enough as those tlds are loaded system-wide on jetty.
    	//to do better than this we need to do it on a per webapp basis.
    	//probably using custom properties in the ContextHandler service
    	//and mirroring those in the MANIFEST.MF
    	
    	Bundle[] bundles = FrameworkUtil.getBundle(PluggableWebAppRegistrationCustomizerImpl.class).getBundleContext().getBundles();
    	Collection<String> tldbundles = getTldBundles(provider);
    	for (Bundle bundle : bundles)
    	{
    		if (tldbundles.contains(bundle.getSymbolicName()))
    		{
    			registerTldBundle(locatorHelper, bundle, urls);
    		}
    	}
    	
    	return urls.toArray(new URL[urls.size()]);

    }
	
    /**
     * Resolves the bundle that contains tld files as a set of URLs that will be
     * passed to jasper as a URLClassLoader later on.
     * Usually that would be a single URL per bundle.
     * But we do some more work if there are jars embedded in the bundle.
     * 
     * The jasper TldScanner expects a URLClassloader to parse a jar for the /META-INF/*.tld it may contain. We place the bundles that we know contain such
     * tag-libraries. Please note that it will work if and only if the bundle is a jar (!) Currently we just hardcode the bundle that contains the jstl
     * implemenation.
     * 
     * A workaround when the tld cannot be parsed with this method is to copy and paste it inside the WEB-INF of the webapplication where it is used.
     * 
     * Support only 2 types of packaging for the bundle: - the bundle is a jar (recommended for runtime.) - the bundle is a folder and contain jars in the root
     * and/or in the lib folder (nice for PDE developement situations) Unsupported: the bundle is a jar that embeds more jars.
     * 
     * @param locatorHelper
     * @param bundle
     * @param urls
     * @throws Exception
     */
    private void registerTldBundle(BundleFileLocatorHelper locatorHelper, Bundle bundle, List<URL> urls) throws Exception
    {
        File jasperLocation = locatorHelper.getBundleInstallLocation(bundle);
        if (jasperLocation.isDirectory())
        {
            for (File f : jasperLocation.listFiles())
            {
                if (f.getName().endsWith(".jar") && f.isFile())
                {
                    urls.add(f.toURI().toURL());
                }
                else if (f.isDirectory() && f.getName().equals("lib"))
                {
                    for (File f2 : jasperLocation.listFiles())
                    {
                        if (f2.getName().endsWith(".jar") && f2.isFile())
                        {
                            urls.add(f2.toURI().toURL());
                        }
                    }
                }
            }
            urls.add(jasperLocation.toURI().toURL());
        }
        else
        {
        	urls.add(jasperLocation.toURI().toURL());
        }

    }
    
}