/*
* Copyright (C) 2013 Glyptodon LLC
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.glyptodon.guacamole.net.basic;
import java.io.File;
import java.io.FilenameFilter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.ArrayList;
import java.util.Collection;
import org.glyptodon.guacamole.GuacamoleException;
import org.glyptodon.guacamole.net.basic.properties.BasicGuacamoleProperties;
import org.glyptodon.guacamole.properties.GuacamoleProperties;
/**
* A ClassLoader implementation which finds classes within a configurable
* directory. This directory is set within guacamole.properties.
*
* @author Michael Jumper
*/
public class GuacamoleClassLoader extends ClassLoader {
/**
* Class loader which will load classes from the classpath specified
* in guacamole.properties.
*/
private URLClassLoader classLoader = null;
/**
* Any exception that occurs while the class loader is being instantiated.
*/
private static GuacamoleException exception = null;
/**
* Singleton instance of the GuacamoleClassLoader.
*/
private static GuacamoleClassLoader instance = null;
static {
try {
// Attempt to create singleton classloader which loads classes from
// all .jar's in the lib directory defined in guacamole.properties
instance = AccessController.doPrivileged(new PrivilegedExceptionAction<GuacamoleClassLoader>() {
@Override
public GuacamoleClassLoader run() throws GuacamoleException {
return new GuacamoleClassLoader(
GuacamoleProperties.getProperty(BasicGuacamoleProperties.LIB_DIRECTORY)
);
}
});
}
catch (PrivilegedActionException e) {
// On error, record exception
exception = (GuacamoleException) e.getException();
}
}
/**
* Creates a new GuacamoleClassLoader which reads classes from the given
* directory.
*
* @param libDirectory The directory to load classes from.
* @throws GuacamoleException If the file given is not a director, or if
* an error occurs while constructing the URL
* for the backing classloader.
*/
private GuacamoleClassLoader(File libDirectory) throws GuacamoleException {
// If no directory provided, just direct requests to parent classloader
if (libDirectory == null)
return;
// Validate directory is indeed a directory
if (!libDirectory.isDirectory())
throw new GuacamoleException(libDirectory + " is not a directory.");
// Get list of URLs for all .jar's in the lib directory
Collection<URL> jarURLs = new ArrayList<URL>();
for (File file : libDirectory.listFiles(new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
// If it ends with .jar, accept the file
return name.endsWith(".jar");
}
})) {
try {
// Add URL for the .jar to the jar URL list
jarURLs.add(file.toURI().toURL());
}
catch (MalformedURLException e) {
throw new GuacamoleException(e);
}
}
// Set delegate classloader to new URLClassLoader which loads from the
// .jars found above.
URL[] urls = new URL[jarURLs.size()];
classLoader = new URLClassLoader(
jarURLs.toArray(urls),
getClass().getClassLoader()
);
}
/**
* Returns an instance of a GuacamoleClassLoader which finds classes
* within the directory configured in guacamole.properties.
*
* @return An instance of a GuacamoleClassLoader.
* @throws GuacamoleException If no instance could be returned due to an
* error.
*/
public static GuacamoleClassLoader getInstance() throws GuacamoleException {
// If instance could not be created, rethrow original exception
if (exception != null) throw exception;
return instance;
}
@Override
public Class<?> findClass(String name) throws ClassNotFoundException {
// If no classloader, use default loader
if (classLoader == null)
return Class.forName(name);
// Otherwise, delegate
return classLoader.loadClass(name);
}
}