Tomcat example source code file (TldConfig.java)

This example Tomcat source code file (TldConfig.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 - Tomcat tags/keywords

exception, exception, file, file, io, ioexception, ioexception, jar, map, naming, net, network, scanning, set, string, string, tld, url, util, web-inf

The Tomcat TldConfig.java source 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.
 */


package org.apache.catalina.startup;


import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import javax.servlet.ServletException;

import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.core.StandardContext;
import org.apache.catalina.util.StringManager;
import org.apache.tomcat.util.digester.Digester;
import org.xml.sax.InputSource;

/**
 * Startup event listener for a <b>Context that configures the properties
 * of that Context, and the associated defined servlets.
 *
 * @author Craig R. McClanahan
 * @author Jean-Francois Arcand
 * @author Costin Manolache
 */
public final class TldConfig  {

    // Names of JARs that are known not to contain any TLDs
    private static HashSet<String> noTldJars;

    private static org.apache.juli.logging.Log log=
        org.apache.juli.logging.LogFactory.getLog( TldConfig.class );

    /*
     * Initializes the set of JARs that are known not to contain any TLDs
     */
    static {
        noTldJars = new HashSet<String>();
        // Bootstrap JARs
        noTldJars.add("bootstrap.jar");
        noTldJars.add("commons-daemon.jar");
        noTldJars.add("tomcat-juli.jar");
        // Main JARs
        noTldJars.add("annotations-api.jar");
        noTldJars.add("catalina.jar");
        noTldJars.add("catalina-ant.jar");
        noTldJars.add("catalina-ha.jar");
        noTldJars.add("catalina-tribes.jar");
        noTldJars.add("el-api.jar");
        noTldJars.add("jasper.jar");
        noTldJars.add("jasper-el.jar");
        noTldJars.add("jasper-jdt.jar");
        noTldJars.add("jsp-api.jar");
        noTldJars.add("servlet-api.jar");
        noTldJars.add("tomcat-coyote.jar");
        noTldJars.add("tomcat-dbcp.jar");
        // i18n JARs
        noTldJars.add("tomcat-i18n-en.jar");
        noTldJars.add("tomcat-i18n-es.jar");
        noTldJars.add("tomcat-i18n-fr.jar");
        noTldJars.add("tomcat-i18n-ja.jar");
        // Misc JARs not included with Tomcat
        noTldJars.add("ant.jar");
        noTldJars.add("commons-dbcp.jar");
        noTldJars.add("commons-beanutils.jar");
        noTldJars.add("commons-fileupload-1.0.jar");
        noTldJars.add("commons-pool.jar");
        noTldJars.add("commons-digester.jar");
        noTldJars.add("commons-logging.jar");
        noTldJars.add("commons-collections.jar");
        noTldJars.add("jmx.jar");
        noTldJars.add("jmx-tools.jar");
        noTldJars.add("xercesImpl.jar");
        noTldJars.add("xmlParserAPIs.jar");
        noTldJars.add("xml-apis.jar");
        // JARs from J2SE runtime
        noTldJars.add("sunjce_provider.jar");
        noTldJars.add("ldapsec.jar");
        noTldJars.add("localedata.jar");
        noTldJars.add("dnsns.jar");
        noTldJars.add("tools.jar");
        noTldJars.add("sunpkcs11.jar");
    }


    // ----------------------------------------------------- Instance Variables

    /**
     * The Context we are associated with.
     */
    private Context context = null;


    /**
     * The string resources for this package.
     */
    private static final StringManager sm =
        StringManager.getManager(Constants.Package);

    /**
     * The <code>Digester we will use to process tag library
     * descriptor files.
     */
    private static Digester tldDigester = null;


    /**
     * Attribute value used to turn on/off TLD validation
     */
     private static boolean tldValidation = false;


    /**
     * Attribute value used to turn on/off TLD  namespace awarenes.
     */
    private static boolean tldNamespaceAware = false;

    private boolean rescan=true;

    private ArrayList<String> listeners = new ArrayList();

    // --------------------------------------------------------- Public Methods

    /**
     * Sets the list of JARs that are known not to contain any TLDs.
     *
     * @param jarNames List of comma-separated names of JAR files that are 
     * known not to contain any TLDs 
     */
    public static void setNoTldJars(String jarNames) {
        if (jarNames != null) {
            noTldJars.clear();
            StringTokenizer tokenizer = new StringTokenizer(jarNames, ",");
            while (tokenizer.hasMoreElements()) {
                noTldJars.add(tokenizer.nextToken());
            }
        }
    }

    /**
     * Set the validation feature of the XML parser used when
     * parsing xml instances.
     * @param tldValidation true to enable xml instance validation
     */
    public void setTldValidation(boolean tldValidation){
        TldConfig.tldValidation = tldValidation;
    }

    /**
     * Get the server.xml <host> attribute's xmlValidation.
     * @return true if validation is enabled.
     *
     */
    public boolean getTldValidation(){
        return tldValidation;
    }

    /**
     * Get the server.xml <host> attribute's xmlNamespaceAware.
     * @return true if namespace awarenes is enabled.
     *
     */
    public boolean getTldNamespaceAware(){
        return tldNamespaceAware;
    }


    /**
     * Set the namespace aware feature of the XML parser used when
     * parsing xml instances.
     * @param tldNamespaceAware true to enable namespace awareness
     */
    public void setTldNamespaceAware(boolean tldNamespaceAware){
        TldConfig.tldNamespaceAware = tldNamespaceAware;
    }    


    public boolean isRescan() {
        return rescan;
    }

    public void setRescan(boolean rescan) {
        this.rescan = rescan;
    }

    public Context getContext() {
        return context;
    }

    public void setContext(Context context) {
        this.context = context;
    }

    public void addApplicationListener( String s ) {
        //if(log.isDebugEnabled())
            log.debug( "Add tld listener " + s);
        listeners.add(s);
    }

    public String[] getTldListeners() {
        String result[]=new String[listeners.size()];
        listeners.toArray(result);
        return result;
    }


    /**
     * Scan for and configure all tag library descriptors found in this
     * web application.
     *
     * @exception Exception if a fatal input/output or parsing error occurs
     */
    public void execute() throws Exception {
        long t1=System.currentTimeMillis();

        File tldCache=null;

        if (context instanceof StandardContext) {
            File workDir= (File)
                ((StandardContext)context).getServletContext().getAttribute(Globals.WORK_DIR_ATTR);
            //tldCache=new File( workDir, "tldCache.ser");
        }

        // Option to not rescan
        if( ! rescan ) {
            // find the cache
            if( tldCache!= null && tldCache.exists()) {
                // just read it...
                processCache(tldCache);
                return;
            }
        }

        /*
         * Acquire the list of TLD resource paths, possibly embedded in JAR
         * files, to be processed
         */
        Set resourcePaths = tldScanResourcePaths();
        Map jarPaths = getJarPaths();

        // Check to see if we can use cached listeners
        if (tldCache != null && tldCache.exists()) {
            long lastModified = getLastModified(resourcePaths, jarPaths);
            if (lastModified < tldCache.lastModified()) {
                processCache(tldCache);
                return;
            }
        }

        // Scan each accumulated resource path for TLDs to be processed
        Iterator paths = resourcePaths.iterator();
        while (paths.hasNext()) {
            String path = (String) paths.next();
            if (path.endsWith(".jar")) {
                tldScanJar(path);
            } else {
                tldScanTld(path);
            }
        }
        if (jarPaths != null) {
            paths = jarPaths.values().iterator();
            while (paths.hasNext()) {
                tldScanJar((File) paths.next());
            }
        }

        String list[] = getTldListeners();

        if( tldCache!= null ) {
            log.debug( "Saving tld cache: " + tldCache + " " + list.length);
            try {
                FileOutputStream out=new FileOutputStream(tldCache);
                ObjectOutputStream oos=new ObjectOutputStream( out );
                oos.writeObject( list );
                oos.close();
            } catch( IOException ex ) {
                ex.printStackTrace();
            }
        }

        if( log.isDebugEnabled() )
            log.debug( "Adding tld listeners:" + list.length);
        for( int i=0; list!=null && i<list.length; i++ ) {
            context.addApplicationListener(list[i]);
        }

        long t2=System.currentTimeMillis();
        if( context instanceof StandardContext ) {
            ((StandardContext)context).setTldScanTime(t2-t1);
        }

    }

    // -------------------------------------------------------- Private Methods

    /*
     * Returns the last modification date of the given sets of resources.
     *
     * @param resourcePaths
     * @param jarPaths
     *
     * @return Last modification date
     */
    private long getLastModified(Set resourcePaths, Map jarPaths)
            throws Exception {

        long lastModified = 0;

        Iterator paths = resourcePaths.iterator();
        while (paths.hasNext()) {
            String path = (String) paths.next();
            URL url = context.getServletContext().getResource(path);
            if (url == null) {
                log.debug( "Null url "+ path );
                break;
            }
            long lastM = url.openConnection().getLastModified();
            if (lastM > lastModified) lastModified = lastM;
            if (log.isDebugEnabled()) {
                log.debug( "Last modified " + path + " " + lastM);
            }
        }

        if (jarPaths != null) {
            paths = jarPaths.values().iterator();
            while (paths.hasNext()) {
                File jarFile = (File) paths.next();
                long lastM = jarFile.lastModified();
                if (lastM > lastModified) lastModified = lastM;
                if (log.isDebugEnabled()) {
                    log.debug("Last modified " + jarFile.getAbsolutePath()
                              + " " + lastM);
                }
            }
        }

        return lastModified;
    }

    private void processCache(File tldCache ) throws IOException {
        // read the cache and return;
        try {
            FileInputStream in=new FileInputStream(tldCache);
            ObjectInputStream ois=new ObjectInputStream( in );
            String list[]=(String [])ois.readObject();
            if( log.isDebugEnabled() )
                log.debug("Reusing tldCache " + tldCache + " " + list.length);
            for( int i=0; list!=null && i<list.length; i++ ) {
                context.addApplicationListener(list[i]);
            }
            ois.close();
        } catch( ClassNotFoundException ex ) {
            ex.printStackTrace();
        }
    }

    /**
     * Create (if necessary) and return a Digester configured to process a tag
     * library descriptor, looking for additional listener classes to be
     * registered.
     */
    private static Digester createTldDigester() {

        return DigesterFactory.newDigester(tldValidation, 
                                           tldNamespaceAware, 
                                           new TldRuleSet());

    }


    /**
     * Scan the JAR file at the specified resource path for TLDs in the
     * <code>META-INF subdirectory, and scan each TLD for application
     * event listeners that need to be registered.
     *
     * @param resourcePath Resource path of the JAR file to scan
     *
     * @exception Exception if an exception occurs while scanning this JAR
     */
    private void tldScanJar(String resourcePath) throws Exception {

        if (log.isDebugEnabled()) {
            log.debug(" Scanning JAR at resource path '" + resourcePath + "'");
        }

        URL url = context.getServletContext().getResource(resourcePath);
        if (url == null) {
            throw new IllegalArgumentException
                                (sm.getString("contextConfig.tldResourcePath",
                                              resourcePath));
        }

        File file = null;
        try {
            file = new File(url.toURI());
        } catch (URISyntaxException e) {
            // Ignore, probably an unencoded char
            file = new File(url.getFile());
        }
        try {
            file = file.getCanonicalFile();
        } catch (IOException e) {
            // Ignore
        }
        tldScanJar(file);

    }

    /**
     * Scans all TLD entries in the given JAR for application listeners.
     *
     * @param file JAR file whose TLD entries are scanned for application
     * listeners
     */
    private void tldScanJar(File file) throws Exception {

        JarFile jarFile = null;
        String name = null;

        String jarPath = file.getAbsolutePath();

        try {
            jarFile = new JarFile(file);
            Enumeration entries = jarFile.entries();
            while (entries.hasMoreElements()) {
                JarEntry entry = (JarEntry) entries.nextElement();
                name = entry.getName();
                if (!name.startsWith("META-INF/")) {
                    continue;
                }
                if (!name.endsWith(".tld")) {
                    continue;
                }
                if (log.isTraceEnabled()) {
                    log.trace("  Processing TLD at '" + name + "'");
                }
                try {
                    tldScanStream(new InputSource(jarFile.getInputStream(entry)));
                } catch (Exception e) {
                    log.error(sm.getString("contextConfig.tldEntryException",
                                           name, jarPath, context.getPath()),
                              e);
                }
            }
        } catch (Exception e) {
            log.error(sm.getString("contextConfig.tldJarException",
                                   jarPath, context.getPath()),
                      e);
        } finally {
            if (jarFile != null) {
                try {
                    jarFile.close();
                } catch (Throwable t) {
                    // Ignore
                }
            }
        }
    }

    /**
     * Scan the TLD contents in the specified input stream, and register
     * any application event listeners found there.  <b>NOTE - It is
     * the responsibility of the caller to close the InputStream after this
     * method returns.
     *
     * @param resourceStream InputStream containing a tag library descriptor
     *
     * @exception Exception if an exception occurs while scanning this TLD
     */
    private void tldScanStream(InputSource resourceStream)
        throws Exception {

        if (tldDigester == null){
            tldDigester = createTldDigester();
        }
        
        synchronized (tldDigester) {
            try {
                tldDigester.push(this);
                tldDigester.parse(resourceStream);
            } finally {
                tldDigester.reset();
            }
        }

    }

    /**
     * Scan the TLD contents at the specified resource path, and register
     * any application event listeners found there.
     *
     * @param resourcePath Resource path being scanned
     *
     * @exception Exception if an exception occurs while scanning this TLD
     */
    private void tldScanTld(String resourcePath) throws Exception {

        if (log.isDebugEnabled()) {
            log.debug(" Scanning TLD at resource path '" + resourcePath + "'");
        }

        InputSource inputSource = null;
        try {
            InputStream stream =
                context.getServletContext().getResourceAsStream(resourcePath);
            if (stream == null) {
                throw new IllegalArgumentException
                (sm.getString("contextConfig.tldResourcePath",
                        resourcePath));
            }
            inputSource = new InputSource(stream);
            if (inputSource == null) {
                throw new IllegalArgumentException
                    (sm.getString("contextConfig.tldResourcePath",
                                  resourcePath));
            }
            tldScanStream(inputSource);
        } catch (Exception e) {
             throw new ServletException
                 (sm.getString("contextConfig.tldFileException", resourcePath,
                               context.getPath()),
                  e);
        } 

    }

    /**
     * Accumulate and return a Set of resource paths to be analyzed for
     * tag library descriptors.  Each element of the returned set will be
     * the context-relative path to either a tag library descriptor file,
     * or to a JAR file that may contain tag library descriptors in its
     * <code>META-INF subdirectory.
     *
     * @exception IOException if an input/output error occurs while
     *  accumulating the list of resource paths
     */
    private Set tldScanResourcePaths() throws IOException {
        if (log.isDebugEnabled()) {
            log.debug(" Accumulating TLD resource paths");
        }
        Set resourcePaths = new HashSet();

        // Accumulate resource paths explicitly listed in the web application
        // deployment descriptor
        if (log.isTraceEnabled()) {
            log.trace("  Scanning <taglib> elements in web.xml");
        }
        String taglibs[] = context.findTaglibs();
        for (int i = 0; i < taglibs.length; i++) {
            String resourcePath = context.findTaglib(taglibs[i]);
            // FIXME - Servlet 2.4 DTD implies that the location MUST be
            // a context-relative path starting with '/'?
            if (!resourcePath.startsWith("/")) {
                resourcePath = "/WEB-INF/" + resourcePath;
            }
            if (log.isTraceEnabled()) {
                log.trace("   Adding path '" + resourcePath +
                    "' for URI '" + taglibs[i] + "'");
            }
            resourcePaths.add(resourcePath);
        }

        DirContext resources = context.getResources();
        if (resources != null) {
            tldScanResourcePathsWebInf(resources, "/WEB-INF", resourcePaths);
        }

        // Return the completed set
        return (resourcePaths);

    }

    /*
     * Scans the web application's subdirectory identified by rootPath,
     * along with its subdirectories, for TLDs.
     *
     * Initially, rootPath equals /WEB-INF. The /WEB-INF/classes and
     * /WEB-INF/lib subdirectories are excluded from the search, as per the
     * JSP 2.0 spec.
     *
     * @param resources The web application's resources
     * @param rootPath The path whose subdirectories are to be searched for
     * TLDs
     * @param tldPaths The set of TLD resource paths to add to
     */
    private void tldScanResourcePathsWebInf(DirContext resources,
                                            String rootPath,
                                            Set tldPaths) 
            throws IOException {

        if (log.isTraceEnabled()) {
            log.trace("  Scanning TLDs in " + rootPath + " subdirectory");
        }

        try {
            NamingEnumeration items = resources.list(rootPath);
            while (items.hasMoreElements()) {
                NameClassPair item = (NameClassPair) items.nextElement();
                String resourcePath = rootPath + "/" + item.getName();
                if (!resourcePath.endsWith(".tld")
                        && (resourcePath.startsWith("/WEB-INF/classes")
                            || resourcePath.startsWith("/WEB-INF/lib"))) {
                    continue;
                }
                if (resourcePath.endsWith(".tld")) {
                    if (log.isTraceEnabled()) {
                        log.trace("   Adding path '" + resourcePath + "'");
                    }
                    tldPaths.add(resourcePath);
                } else {
                    tldScanResourcePathsWebInf(resources, resourcePath,
                                               tldPaths);
                }
            }
        } catch (NamingException e) {
            ; // Silent catch: it's valid that no /WEB-INF directory exists
        }
    }

    /**
     * Returns a map of the paths to all JAR files that are accessible to the
     * webapp and will be scanned for TLDs.
     *
     * The map always includes all the JARs under WEB-INF/lib, as well as
     * shared JARs in the classloader delegation chain of the webapp's
     * classloader.
     *
     * The latter constitutes a Tomcat-specific extension to the TLD search
     * order defined in the JSP spec. It allows tag libraries packaged as JAR
     * files to be shared by web applications by simply dropping them in a 
     * location that all web applications have access to (e.g.,
     * <CATALINA_HOME>/common/lib).
     *
     * The set of shared JARs to be scanned for TLDs is narrowed down by
     * the <tt>noTldJars class variable, which contains the names of JARs
     * that are known not to contain any TLDs.
     *
     * @return Map of JAR file paths
     */
    private Map getJarPaths() {

        HashMap jarPathMap = null;

        ClassLoader webappLoader = Thread.currentThread().getContextClassLoader();
        ClassLoader loader = webappLoader;
        while (loader != null) {
            if (loader instanceof URLClassLoader) {
                URL[] urls = ((URLClassLoader) loader).getURLs();
                for (int i=0; i<urls.length; i++) {
                    // Expect file URLs, these are %xx encoded or not depending on
                    // the class loader
                    // This is definitely not as clean as using JAR URLs either
                    // over file or the custom jndi handler, but a lot less
                    // buggy overall
                    File file = null;
                    try {
                        file = new File(urls[i].toURI());
                    } catch (URISyntaxException e) {
                        // Ignore, probably an unencoded char
                        file = new File(urls[i].getFile());
                    }
                    try {
                        file = file.getCanonicalFile();
                    } catch (IOException e) {
                        // Ignore
                    }
                    if (!file.exists()) {
                        continue;
                    }
                    String path = file.getAbsolutePath();
                    if (!path.endsWith(".jar")) {
                        continue;
                    }
                    /*
                     * Scan all JARs from WEB-INF/lib, plus any shared JARs
                     * that are not known not to contain any TLDs
                     */
                    if (loader == webappLoader
                            || noTldJars == null
                            || !noTldJars.contains(file.getName())) {
                        if (jarPathMap == null) {
                            jarPathMap = new HashMap();
                            jarPathMap.put(path, file);
                        } else if (!jarPathMap.containsKey(path)) {
                            jarPathMap.put(path, file);
                        }
                    }
                }
            }
            loader = loader.getParent();
        }

        return jarPathMap;
    }
}