org.milyn.classpath.CascadingClassLoaderSet Maven / Gradle / Ivy
/*
* Milyn - Copyright (C) 2006 - 2010
*
* This library 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.
*
* This library 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:
* http://www.gnu.org/licenses/lgpl.txt
*/
package org.milyn.classpath;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
/**
* Cascading {@link ClassLoader} set.
*
* @author [email protected]
*/
public class CascadingClassLoaderSet extends ClassLoader {
List classLoaders = new ArrayList();
private int classLoaderCount;
public CascadingClassLoaderSet addClassLoader(ClassLoader classLoader) {
classLoaders.add(classLoader);
classLoaderCount = classLoaders.size();
return this;
}
@Override
public Class loadClass(String s) throws ClassNotFoundException {
for (int i = 0; i < classLoaderCount; i++) {
ClassLoader classLoader = classLoaders.get(i);
try {
Class klass = classLoader.loadClass(s);
if (klass != null) {
return klass;
}
} catch (ClassNotFoundException e) {
// Try the next classloader...
}
}
throw new ClassNotFoundException("Failed to find class '" + s + "'.");
}
@Override
public URL getResource(String s) {
for (int i = 0; i < classLoaderCount; i++) {
ClassLoader classLoader = classLoaders.get(i);
URL resource = classLoader.getResource(s);
if (resource != null) {
return resource;
}
}
return null;
}
@Override
public Enumeration getResources(String s) throws IOException {
List resources = new ArrayList();
for (int i = 0; i < classLoaderCount; i++) {
ClassLoader classLoader = classLoaders.get(i);
Enumeration resourcesEnum = classLoader.getResources(s);
if(resourcesEnum.hasMoreElements()) {
resources.addAll(Collections.list(resourcesEnum));
}
}
return Collections.enumeration(resources);
}
@Override
public InputStream getResourceAsStream(String s) {
for (int i = 0; i < classLoaderCount; i++) {
ClassLoader classLoader = classLoaders.get(i);
InputStream resource = classLoader.getResourceAsStream(s);
if (resource != null) {
return resource;
}
}
return null;
}
}