org.infinispan.commons.util.AggregatedClassLoader Maven / Gradle / Ivy
package org.infinispan.commons.util;
import java.io.IOException;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* A ClassLoader that delegates loading of classes and resources to a list of delegate ClassLoaders. The loading is
* attempted in the order returned by the provided {@link Collection}.
*
* @author [email protected]
* @since 9.2
*/
public final class AggregatedClassLoader extends ClassLoader {
private final ClassLoader[] classLoaders;
/**
* Create an aggregated ClassLoader from a Collection of ClassLoaders
*
* @param classLoaders a non-empty Collection of ClassLoaders
*/
public AggregatedClassLoader(Collection classLoaders) {
super(null);
if (classLoaders == null || classLoaders.isEmpty()) {
throw new IllegalArgumentException("classLoaders argument cannot be null or empty");
}
this.classLoaders = classLoaders.toArray(new ClassLoader[classLoaders.size()]);
}
@Override
public Enumeration getResources(String name) throws IOException {
Set urls = new HashSet<>();
for (ClassLoader cl : classLoaders) {
Enumeration resources = cl.getResources(name);
while (resources.hasMoreElements()) {
urls.add(resources.nextElement());
}
}
return new Enumeration() {
final Iterator it = urls.iterator();
@Override
public boolean hasMoreElements() {
return it.hasNext();
}
@Override
public URL nextElement() {
return it.next();
}
};
}
@Override
protected URL findResource(String name) {
for (ClassLoader cl : classLoaders) {
URL res = cl.getResource(name);
if (res != null) {
return res;
}
}
return super.findResource(name);
}
@Override
protected Class findClass(String name) throws ClassNotFoundException {
for (ClassLoader cl : classLoaders) {
try {
return cl.loadClass(name);
} catch (Exception ex) {
// ignored
}
}
throw new ClassNotFoundException(name);
}
}