org.apache.spark.util.ChildFirstURLClassLoader Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.util;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
/**
* A mutable class loader that gives preference to its own URLs over the parent class loader
* when loading classes and resources.
*/
public class ChildFirstURLClassLoader extends MutableURLClassLoader {
static {
ClassLoader.registerAsParallelCapable();
}
private ParentClassLoader parent;
public ChildFirstURLClassLoader(URL[] urls, ClassLoader parent) {
super(urls, null);
this.parent = new ParentClassLoader(parent);
}
@Override
public Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
try {
return super.loadClass(name, resolve);
} catch (ClassNotFoundException cnf) {
return parent.loadClass(name, resolve);
}
}
@Override
public Enumeration getResources(String name) throws IOException {
ArrayList urls = Collections.list(super.getResources(name));
urls.addAll(Collections.list(parent.getResources(name)));
return Collections.enumeration(urls);
}
@Override
public URL getResource(String name) {
URL url = super.getResource(name);
if (url != null) {
return url;
} else {
return parent.getResource(name);
}
}
}