com.wavemaker.commons.classloader.WMUrlClassLoader Maven / Gradle / Ivy
/**
* Copyright (C) 2020 WaveMaker, Inc.
*
* Licensed 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 com.wavemaker.commons.classloader;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Collections;
import java.util.Enumeration;
import sun.misc.CompoundEnumeration;
public class WMUrlClassLoader extends URLClassLoader {
private String loaderContext;
static {
ClassLoader.registerAsParallelCapable();
}
public WMUrlClassLoader(URL[] urls, String loaderContext, ClassLoader parent) {
super(urls, parent);
this.loaderContext = loaderContext;
}
public WMUrlClassLoader(URL[] urls, String loaderContext) {
this(urls, loaderContext, Thread.currentThread().getContextClassLoader());
}
@Override
public String toString() {
return "WMUrlClassLoader{loaderContext='" + loaderContext + '\'' +"} ";
}
/**
* If we want to load a resource and it is available in both the parent classloader and the child classloader,
* then the default behaviour is, first it will check in the parent classloader if it not found then it will check in the child classloader.
* So if we want to load the this type resource, we will always get the resource from the parent classloader, child's resource will never get loaded.
*
* To solve this first we are checking in the child classloader, if it is not found then checking in the parent classloader.
* @param name The resource name
* @return A URL object for reading the resource, or
* null if the resource could not be found or the invoker
* doesn't have adequate privileges to get the resource.
*/
@Override
public URL getResource(String name) {
URL url = findResource(name);
if (url == null) {
url = super.getResource(name);
}
return url;
}
@Override
public Enumeration getResources(String name) throws IOException {
Enumeration[] tmp = (Enumeration[]) new Enumeration[2];
tmp[0] = findResources(name);
tmp[1] = getParent() != null ? getParent().getResources(name) : Collections.emptyEnumeration();
return new CompoundEnumeration(tmp);
}
}