Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2013 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.andami.plugins;

import java.io.DataInputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLClassLoader;

import java.security.AllPermission;

import java.security.CodeSource;

import java.security.PermissionCollection;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Enumeration;

import java.util.HashSet;

import java.util.Hashtable;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.Set;

import java.util.StringTokenizer;

import java.util.zip.ZipEntry;

import java.util.zip.ZipException;

import java.util.zip.ZipFile;

import org.gvsig.andami.messages.Messages;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * <p>Class loader which loads the classes requested by the

 * plugins. It first tries to search in the classpath, then it requests

 * the class to the parent classloader, then it searches in the owns

 * plugins' library dir, and if all these methods fail, it tries to load

 * the class from any of the depended plugins. Finally, if this also

 * fails, the other classloaders provided in the <code>addLoaders</code> method

 * are requested to load the class.</p>

 * 

 * <p>The class loader can also be used to load resources from the

 * plugin's directory by using the <code>getResource()</code> method.</p>

 *

 * @author Fernando Gonz�lez Cort�s

 */

public class PluginClassLoader extends URLClassLoader {

    /** DOCUMENT ME! */

    private static Logger logger = LoggerFactory.getLogger(PluginClassLoader.class.getName());

    /** DOCUMENT ME! */

    private Hashtable<String, ZipFile> clasesJar = new Hashtable<String, ZipFile>();

    /** DOCUMENT ME! */

    private File baseDir;

    private List<PluginClassLoader> pluginLoaders;

    private static List<ClassLoader> otherLoaders=new ArrayList<ClassLoader>();

    private boolean isOtherLoader=false;

    /**

     * Creates a new PluginClassLoader object.

     *

     * @param jars Array with the search paths where classes will be searched

     * @param baseDir Base directory for this plugin. This is the directory

     * which will be used as basedir in the <code>getResources</code> method.

     * @param cl The parent classloader of this classloader. It will be used to

     * search classes before trying to search in the plugin's directory

     * @param pluginLoaders The classloaders of the depended plugins.

     *

     * @throws IOException

     */

    public PluginClassLoader(URL[] jars, String baseDir, ClassLoader cl,

        PluginClassLoader[] pluginLoaders) throws IOException {

        this(jars, baseDir, cl, Arrays.asList(pluginLoaders));

    }

    public PluginClassLoader(URL[] jars, String baseDir, ClassLoader cl,

            List<PluginClassLoader> pluginLoaders) throws IOException {

        super(jars, cl);

        logger.debug("Creating PluginClassLoader for {}.", baseDir);

        this.baseDir = new File(new File(baseDir).getAbsolutePath());

        this.pluginLoaders = new ArrayList();

        this.pluginLoaders.addAll(pluginLoaders);

        if( jars==null || jars.length<1 ) { 

            debugDump(); 

                return;

        }

        ZipFile[] jarFiles = new ZipFile[jars.length];

        for (int i = 0; i < jars.length; i++) {

            try {

                jarFiles[i] = new ZipFile(jars[i].getPath());

                Enumeration<? extends ZipEntry> entradas = jarFiles[i].entries();

                while (entradas.hasMoreElements()) {

                    ZipEntry file = (ZipEntry) entradas.nextElement();

                    String fileName = file.getName();

                    if (!fileName.toLowerCase().endsWith(".class")) { //$NON-NLS-1$

                        continue;

                    }

                    fileName = fileName.substring(0, fileName.length() - 6)

                                       .replace('/', '.');

                    if (clasesJar.get(fileName) != null) {

                                                logger.warn("Duplicated class {} in {} and {}",

                                                        new Object[] {

                                                                fileName, 

                                                                jarFiles[i].getName(),

                                                                clasesJar.get(fileName).getName()

                                                        }

                                                );

                    }

                    else {

                            clasesJar.put(fileName, jarFiles[i]);

                    }

                }

            } catch (ZipException e) {

                throw new IOException(e.getMessage() + " Jar: " +

                    jars[i].getPath() + ": " + jarFiles[i]);

            } catch (IOException e) {

                throw e;

            } finally {

                debugDump(); 

            }

        }

    }

    private void debugDump() {

            if( !logger.isDebugEnabled() ) {

                    return;

            }

            logger.debug(this.toString());

            logger.debug("  baseDir: " + this.baseDir);

            logger.debug("  parent: " + this.getParent());

            logger.debug("  depends:");

            for( int n=0; n<this.pluginLoaders.size(); n++ ) {

                    logger.debug("    {}", this.pluginLoaders.get(n).toString() );

            }

            logger.debug("  urls:");

            URL[] urls = this.getURLs();

            for( int n=0 ; n<urls.length; n++ ) {

                    logger.debug("    " + urls[n].toString());

            }

            logger.debug("  classes:");

            Iterator<Map.Entry<String, ZipFile>>it = this.clasesJar.entrySet().iterator();

            while( it.hasNext() ) {

                    Entry<String, ZipFile> entry = it.next();

                    logger.debug("    "+ entry.getKey() + "("+entry.getValue().getName()+")");

            }

    }

    protected Class singleLoadClass(String name) throws ClassNotFoundException {

        Class<?> c;

        Set<String>pluginsVisiteds = new HashSet<String>();

        c = this.singleLoadClass(pluginsVisiteds, name);

        return c;

    }

    /**

     * Carga la clase

     *

     * @param name Nombre de la clase

     * @param resolve Si se ha de resolver la clase o no

     *

     * @return Clase cargada

     *

     * @throws ClassNotFoundException Si no se pudo encontrar la clase

     */

    protected Class loadClass(String name, boolean resolve)

        throws ClassNotFoundException {

        Class<?> c = null;

        // Intentamos cargar con el system classloader

        try {

            if (!isOtherLoader)

                    c = super.loadClass(name, resolve);

            logger.debug("Found class {} in system-classloader", name);

        } catch (ClassNotFoundException e1) {

                try {

                        c = singleLoadClass(name);

                } catch (ClassNotFoundException e2) {

                        try {

                                isOtherLoader=true;

                                c = loadOtherClass(name);

                        }catch (ClassNotFoundException e3) {

                    // throw new ClassNotFoundException(Messages.getString(

                    // "PluginClassLoader.Error_reading_file")

                    // + name, e3);

                    throw new ClassNotFoundException("Class " + name

                            + " not found through the plugin " + baseDir, e3);                                 

                        }finally {

                                isOtherLoader=false;

                        }

                }

        }

        if (c==null)

                 throw new ClassNotFoundException(Messages.getString(

             "PluginClassLoader.Error_reading_file") + name);

        if (resolve) {

            resolveClass(c);

        }

        return c;

    }

    private Class<?> loadOtherClass(String name)

            throws ClassNotFoundException {

        ClassLoader[] ocl = (ClassLoader[]) otherLoaders.toArray(new ClassLoader[0]);

        Class<?> c = null;

        for (int i = 0; i < ocl.length; i++) {

            c = ocl[i].loadClass(name);

            if (c != null) {

                logger.debug("Found class {} by the alternative classloaders of plugin {}",

                        name, baseDir);

                return c;

            }

        }

        throw new ClassNotFoundException(name);

    }

    /**

     * obtiene el array de bytes de la clase

     *

     * @param classFile Entrada dentro del jar contiene los bytecodes de la

     *        clase (el .class)

     * @param is InputStream para leer la entrada del jar

     *

     * @return Bytes de la clase

     *

     * @throws IOException Si no se puede obtener el .class del jar

     */

    private byte[] loadClassData(ZipEntry classFile, InputStream is)

        throws IOException {

        // Get size of class file

        int size = (int) classFile.getSize();

        // Reserve space to read

        byte[] buff = new byte[size];

        // Get stream to read from

        DataInputStream dis = new DataInputStream(is);

        // Read in data

        dis.readFully(buff);

        // close stream

        dis.close();

        // return data

        return buff;

    }

    /**

     * Gets the bytes of a File

     *

     * @param file File

     *

     * @return bytes of file

     *

     * @throws IOException If the operation fails

     */

    private byte[] loadClassData(File file) throws IOException {

        InputStream is = new FileInputStream(file);

        // Get the size of the file

        long length = file.length();

        // You cannot create an array using a long type.

        // It needs to be an int type.

        // Before converting to an int type, check

        // to ensure that file is not larger than Integer.MAX_VALUE.

        if (length > Integer.MAX_VALUE) {

            // File is too large

        }

        // Create the byte array to hold the data

        byte[] bytes = new byte[(int) length];

        // Read in the bytes

        int offset = 0;

        int numRead = 0;

        while ((offset < bytes.length) &&

                ((numRead = is.read(bytes, offset, bytes.length - offset)) >= 0)) {

            offset += numRead;

        }

        // Close the input stream and return bytes

        is.close();

        // Ensure all the bytes have been read in

        if (offset < bytes.length) {

            throw new IOException("Could not completely read file " +

                file.getName());

        }

        return bytes;

    }

    /**

     * Gets the requested resource. If the path is relative, its base directory

     * will be the one provided in the PluginClassLoader's constructor.

     * If the resource is not found, search in dependents plugins, otherwise 

     * the parent classloader will be invoked to try to get it. 

     * If it is not found, it will return null.

     *

     * @param res An absolute or relative path to the requested resource.

     *

     * @return Resource's URL if it was found, nul otherwise.

     */

    public URL getResource(String res) {

        URL ret = null;

        Set<String>pluginsVisiteds = new HashSet<String>();

        ret = this.getResource(pluginsVisiteds, res);

        return ret;

    }

    /**

     * Gets the requested resource. If the path is relative, its base directory

     * will be the one provided in the PluginClassLoader's constructor.

     * If the resource is not found, the parent classloader will be invoked

     * to try to get it. If it is not found, it will return null.

     *

     * @param res An absolute or relative path to the requested resource.

     *

     * @return Resource's URL if it was found, nul otherwise.

     */

    private URL getResource(File base, List<String> res) {

        File[] files = base.listFiles();

        String parte = res.get(0);

        for (int i = 0; i < files.length; i++) {

            if (files[i].getName().compareTo(parte) == 0) {

                if (res.size() == 1) {

                    try {

                        return new URL("file:" + files[i].toString());

                    } catch (MalformedURLException e) {

                        return null;

                    }

                } else {

                    return getResource(files[i], res.subList(1, res.size()));

                }

            }

        }

        return null;

    }

    /**

     * Returns the name of the plugin (the name of the directory containing

     * the plugin).

     *

     * @return An String containing the plugin's name.

     */

    public String getPluginName() {

            return baseDir.getName();

    }

    /*

     * @see java.security.SecureClassLoader#getPermissions(java.security.CodeSource)

     */

    protected PermissionCollection getPermissions(CodeSource codesource) {

        PermissionCollection perms = super.getPermissions(codesource);

        perms.add(new AllPermission());

        return perms;

    }

    /**

     * Gets the plugin's base Iterator<Map.Entry<Integer, Integer>>dir, the directory which will be used to

     * search resources.

     *

     * @return Returns the baseDir.

     */

    public String getBaseDir() {

        return baseDir.getAbsolutePath();

    }

    /**

     * Adds other classloader to use when all the normal methods fail.

     * 

     * @param classLoaders An ArrayList of ClassLoaders which will

     * be used to load classes when all the normal methods fail.

     */

        public static void addLoaders(ArrayList classLoaders) {

                otherLoaders.addAll(classLoaders);

        }

    @Override

    public String toString() {

        return super.toString() + " (" + getPluginName() + ")";

    }

    public void addPluginClassLoader(PluginClassLoader pluginClassLoader) {

        if( !this.pluginLoaders.contains(pluginClassLoader) ) {

            this.pluginLoaders.add(pluginClassLoader);

        }

    }

    private Class singleLoadClass(Set<String> pluginsVisiteds, String name) throws ClassNotFoundException {

        if ( pluginsVisiteds.contains(this.getPluginName()) ) {

            return null;

        }

        pluginsVisiteds.add(this.getPluginName());

        // Buscamos en las clases de las librer�as del plugin

        Class<?> c = findLoadedClass(name);

        if (c != null) {

            return c;

        }

        logger.debug("Searching class '{}' in {}", new Object[] {name, this.toString()});

        try {

            ZipFile jar = (ZipFile) clasesJar.get(name);

            //No esta en ningun jar

            if (jar == null) {

                //Buscamos en el directorio de clases

                String classFileName = baseDir + "/classes/" +

                    name.replace('.', '/') + ".class";

                File f = new File(classFileName);

                if (f.exists()){

                    byte[] data = loadClassData(f);

                    c = defineClass(name, data, 0, data.length);

                    logger.debug("Found class {} in classes-folder of plugin {}",

                                    new Object[] {name, baseDir});

                } else {

                    //Buscamos en los otros plugins

                    for ( int i = 0; i < pluginLoaders.size(); i++ ) {

                        c = null;

                        if ( pluginLoaders.get(i) != null ) {

                            try {

                                c = pluginLoaders.get(i).singleLoadClass(pluginsVisiteds, name);

                            } catch (ClassNotFoundException e) {

                                // Si no la encontramos en el primer plugin, capturamos la exceptcion

                                // porque es probable que la encontremos en el resto de plugins.

                            }

                        }

                        if ( c != null ) {

                            return c;

                        }

                    }

                }

            } else {

                String fileName = name.replace('.', '/') + ".class";

                ZipEntry classFile = jar.getEntry(fileName);

                byte[] data = loadClassData(classFile,

                        jar.getInputStream(classFile));

                c = defineClass(name, data, 0, data.length);

                logger.debug("Found class {} in jar {} of plugin {}",

                            new Object[] { name, jar.getName(), baseDir} );

            }

            if (c == null) {

                throw new ClassNotFoundException(name);

            }

            return c;

        } catch (IOException e) {

            throw new ClassNotFoundException(Messages.getString(

                    "PluginClassLoader.Error_reading_file") + name);

        }        

    }

    /**

     * Este metodo busca en este class loader y en el de los plugins

     * de los que depende. Se cerciora de que no se queda

     * bucleado cuando hay una relacion recursiva entre los plugins.

     * 

     * @param pluginsVisiteds, set con los plugins que va visitando para evitar 

     *      que se quede bucleado cuando hay referencia ciclicas entre plugins.

     * @param res

     * 

     * @return 

     */

     private URL getResource(Set<String> pluginsVisiteds, String res) {

        URL ret = null;

        if ( pluginsVisiteds.contains(this.getPluginName()) ) {

            return null;

        }

        pluginsVisiteds.add(this.getPluginName());

        //

        // Primero buscamos en el directorio del plugin.

        try {

            logger.debug("Plugin {}. Searching resource '{}'", res, this.getPluginName());

            List<String> resource = new ArrayList<String>();

            StringTokenizer st = new StringTokenizer(res, "\\/");

            while ( st.hasMoreTokens() ) {

                String token = st.nextToken();

                resource.add(token);

            }

            ret = getResource(baseDir, resource);

            if ( ret != null ) {

                return ret;

            }

        } catch (Exception e) {

            logger.warn("Plugin {}. Error getting resource '{}'.", new Object[]{this.getPluginName(), res}, e);

        }

        logger.debug("Plugin {}. Searching in depends pluginLoaders", this.getPluginName());

        for ( int i = 0; i < this.pluginLoaders.size(); i++ ) {

            PluginClassLoader pluginClassLoader = pluginLoaders.get(i);

            if ( pluginClassLoader != null ) {

                try {

                    pluginsVisiteds.add(pluginClassLoader.getPluginName());

                    ret = pluginClassLoader.getResource(pluginsVisiteds, res);

                    if ( ret != null ) {

                        logger.trace("Plugin {}. Found resource '{}' in plugin '{}'.",

                                new Object[]{

                                    this.getPluginName(), pluginClassLoader.getPluginName(), res

                                });

                        return ret;

                    }

                } catch (Exception e) {

                    // Ignore, try in next classloader

                }

            }

        }

        if ( ret == null ) {

            //

            // Por ultimo en el class loader padre, se supone que es el del sistema.

            try {

                ret = super.getResource(res);

            } catch (Exception e) {

                logger.warn("Plugin {}. Error getting resource '{}' in parent classloader'", new Object[]{this.getPluginName(), res}, e);

            }

            if ( ret == null ) {

                logger.debug("Plugin {}. Resource '{}' not found.", new Object[]{this.getPluginName(), res});

            }

        }

        return ret;

    }

}