org.springframework.boot.loader.LaunchedURLClassLoader Maven / Gradle / Ivy
/*
* Copyright 2012-2014 the original author or authors.
*
* 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 org.springframework.boot.loader;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import org.springframework.boot.loader.jar.Handler;
import org.springframework.boot.loader.jar.JarFile;
/**
* {@link ClassLoader} used by the {@link Launcher}.
*
* @author Phillip Webb
* @author Dave Syer
*/
public class LaunchedURLClassLoader extends URLClassLoader {
private final ClassLoader rootClassLoader;
/**
* Create a new {@link LaunchedURLClassLoader} instance.
* @param urls the URLs from which to load classes and resources
* @param parent the parent class loader for delegation
*/
public LaunchedURLClassLoader(URL[] urls, ClassLoader parent) {
super(urls, parent);
this.rootClassLoader = findRootClassLoader(parent);
}
private ClassLoader findRootClassLoader(ClassLoader classLoader) {
while (classLoader != null) {
if (classLoader.getParent() == null) {
return classLoader;
}
classLoader = classLoader.getParent();
}
return null;
}
@Override
public URL getResource(String name) {
URL url = null;
if (this.rootClassLoader != null) {
url = this.rootClassLoader.getResource(name);
}
return (url == null ? findResource(name) : url);
}
@Override
public URL findResource(String name) {
try {
if (name.equals("") && hasURLs()) {
return getURLs()[0];
}
return super.findResource(name);
}
catch (IllegalArgumentException ex) {
return null;
}
}
@Override
public Enumeration findResources(String name) throws IOException {
if (name.equals("") && hasURLs()) {
return Collections.enumeration(Arrays.asList(getURLs()));
}
return super.findResources(name);
}
private boolean hasURLs() {
return getURLs().length > 0;
}
@Override
public Enumeration getResources(String name) throws IOException {
if (this.rootClassLoader == null) {
return findResources(name);
}
final Enumeration rootResources = this.rootClassLoader.getResources(name);
final Enumeration localResources = findResources(name);
return new Enumeration() {
@Override
public boolean hasMoreElements() {
return rootResources.hasMoreElements()
|| localResources.hasMoreElements();
}
@Override
public URL nextElement() {
if (rootResources.hasMoreElements()) {
return rootResources.nextElement();
}
return localResources.nextElement();
}
};
}
/**
* Attempt to load classes from the URLs before delegating to the parent loader.
*/
@Override
protected Class loadClass(String name, boolean resolve)
throws ClassNotFoundException {
synchronized (this) {
Class loadedClass = findLoadedClass(name);
if (loadedClass == null) {
Handler.setUseFastConnectionExceptions(true);
try {
loadedClass = doLoadClass(name);
}
finally {
Handler.setUseFastConnectionExceptions(false);
}
}
if (resolve) {
resolveClass(loadedClass);
}
return loadedClass;
}
}
private Class doLoadClass(String name) throws ClassNotFoundException {
// 1) Try the root class loader
try {
if (this.rootClassLoader != null) {
return this.rootClassLoader.loadClass(name);
}
}
catch (Exception ex) {
}
// 2) Try to find locally
try {
findPackage(name);
Class cls = findClass(name);
return cls;
}
catch (Exception ex) {
}
// 3) Use standard loading
return super.loadClass(name, false);
}
private void findPackage(final String name) throws ClassNotFoundException {
int lastDot = name.lastIndexOf('.');
if (lastDot != -1) {
String packageName = name.substring(0, lastDot);
if (getPackage(packageName) == null) {
try {
definePackageForFindClass(name, packageName);
}
catch (Exception ex) {
// Swallow and continue
}
}
}
}
/**
* Define a package before a {@code findClass} call is made. This is necessary to
* ensure that the appropriate manifest for nested JARs associated with the package.
* @param name the class name being found
* @param packageName the package
*/
private void definePackageForFindClass(final String name, final String packageName) {
try {
AccessController.doPrivileged(new PrivilegedExceptionAction