/*
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* 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 Lesser General Public License for more details.
*
* Copyright 2009 Pentaho Corporation. All rights reserved.
*
*/
package org.pentaho.platform.plugin.services.pluginmgr;
import java.io.File;
import java.io.FilenameFilter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.io.filefilter.WildcardFileFilter;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.pentaho.platform.engine.services.messages.Messages;
/**
* A custom implementation of {@link URLClassLoader} for Pentaho Platform Plugins.
* It is used to load plugin jars and classes and aids in retrieving resources by providing
* a root directory to search for resources related to plugins.
* <p>
* Note: {@link PluginClassLoader} will search for jar files in a 'lib' subdirectory
* under the pluginDir provided in the constructor. Class and other resources will
* be visible to this classloader in either the root directory of the plugin or in
* the lib folder.
* @author aphillips
*/
public class PluginClassLoader extends URLClassLoader {
private static Log log = LogFactory.getLog(PluginClassLoader.class);
private File pluginDir;
private boolean overrideLoad = false;
/**
* Creates a class loader for loading plugin classes and discovering resources.
* Jars must be located in [pluginDir]/lib.
* @param pluginDir the root directory of the plugin
* @param parent the parent classloader
*/
public PluginClassLoader(final File pluginDir, ClassLoader parent) {
super(getPluginUrls(pluginDir), parent);
this.pluginDir = pluginDir;
if (log.isDebugEnabled()) {
log.debug("URLs for this classloader:"); //$NON-NLS-1$
for (URL url : getURLs()) {
log.debug(url);
}
}
}
/**
* Convenience method that creates a {@link PluginClassLoader} with the current
* classloader as it's parent.
* @param pluginDir the root directory of the plugin
* @param o the object from which the parent classloader will be derived
*/
public PluginClassLoader(final File pluginDir, Object o) {
this(pluginDir, o.getClass().getClassLoader());
}
/**
* Controls whether or not this classloader will eagerly load a class
* requested by {@link #loadClass(String, boolean)} ahead of the parent
* classloader. or delegate the load to the parent. If this method
* is not called, the default behavior will apply which is to *not*
* override classloading.
* @param b if true, loadClass method will look to this loader first to load a class,
* otherwise, the parent classloader will be queried first.
*/
public void setOverrideLoad(boolean b) {
overrideLoad = b;
if (b) {
log.debug("classloader "+this+" is set to override mode. loadClass will now attempt to load " //$NON-NLS-1$ //$NON-NLS-2$
+ "the class from the classpath known to this classloader before delegating to the parent classloader"); //$NON-NLS-1$
}
}
protected static URL[] getPluginUrls(File pluginDir) {
List<URL> urls = new ArrayList<URL>();
File libDir = new File(pluginDir, "lib"); //$NON-NLS-1$
try {
urls.add(pluginDir.toURI().toURL());
urls.add(libDir.toURI().toURL());
} catch (MalformedURLException e) {
log.warn(Messages.getInstance().getString(
"PluginClassLoader.WARN_FAILED_TO_ADD_PLUGIN_DIR_TO_CLASSPATH", pluginDir //$NON-NLS-1$
.getAbsolutePath(), libDir.getAbsolutePath()), e);
}
addJars(urls, libDir);
return urls.toArray(new URL[urls.size()]);
}
protected static void addJars(List<URL> urls, File folder) {
if (folder.exists() && folder.isDirectory()) {
// get a list of all the JAR files
FilenameFilter filter = new WildcardFileFilter("*.jar"); //$NON-NLS-1$
File jarFiles[] = folder.listFiles(filter);
if (jarFiles != null && jarFiles.length > 0) {
for (File file : jarFiles) {
URL url = null;
try {
url = file.toURI().toURL();
if (log.isDebugEnabled()) {
log.debug("adding jar to plugin classloader: " + url.toString()); //$NON-NLS-1$
}
urls.add(url);
} catch (MalformedURLException e) {
log.warn(MessageFormat.format("PluginClassLoader.WARN_FAILED_TO_ADD_JAR_TO_CLASSPATH", file //$NON-NLS-1$
.getAbsolutePath()), e);
}
}
}
}
}
public File getPluginDir() {
return pluginDir;
}
@Override
public Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
if (log.isDebugEnabled()) {
log.debug("loadClass(" + name + ")... "); //$NON-NLS-1$ //$NON-NLS-2$
}
Class<?> t = null;
t = findLoadedClass(name);
if (t != null) {
if (log.isDebugEnabled())
log.debug(MessageFormat.format("{0} loaded by {1}", name, t.getClassLoader())); //$NON-NLS-1$
return t;
}
if (overrideLoad) {
try {
t = findClass(name);
if (t != null) {
if (log.isDebugEnabled()) {
log.debug(MessageFormat.format("{0} loaded by {1}", name, this)); //$NON-NLS-1$
}
if (resolve)
resolveClass(t);
return t;
}
} catch (ClassNotFoundException e) {
if (log.isTraceEnabled()) {
log.trace(MessageFormat.format("class {0} not found in loader {1}. Trying parent loader", name, this)); //$NON-NLS-1$
}
}
}
t = super.loadClass(name, resolve);
if (log.isDebugEnabled()) {
log.debug(MessageFormat.format("{0} loaded by {1}", name, t.getClassLoader())); //$NON-NLS-1$
}
return t;
}
@Override
public String toString() {
return super.toString() + ((pluginDir != null) ? " at " + pluginDir.getAbsolutePath() : ""); //$NON-NLS-1$ //$NON-NLS-2$
}
}