jjg@372: /*
ohair@554:  * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
jjg@372:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jjg@372:  *
jjg@372:  * This code is free software; you can redistribute it and/or modify it
jjg@372:  * under the terms of the GNU General Public License version 2 only, as
ohair@554:  * published by the Free Software Foundation.  Oracle designates this
jjg@372:  * particular file as subject to the "Classpath" exception as provided
ohair@554:  * by Oracle in the LICENSE file that accompanied this code.
jjg@372:  *
jjg@372:  * This code is distributed in the hope that it will be useful, but WITHOUT
jjg@372:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jjg@372:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jjg@372:  * version 2 for more details (a copy is included in the LICENSE file that
jjg@372:  * accompanied this code).
jjg@372:  *
jjg@372:  * You should have received a copy of the GNU General Public License version
jjg@372:  * 2 along with this work; if not, write to the Free Software Foundation,
jjg@372:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jjg@372:  *
ohair@554:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
ohair@554:  * or visit www.oracle.com if you need additional information or have any
ohair@554:  * questions.
jjg@372:  */
jjg@372: 
jjg@450: package com.sun.tools.javac.util;
jjg@372: 
jjg@372: import java.io.Closeable;
jjg@372: import java.io.IOException;
jjg@372: import java.lang.reflect.Field;
jjg@372: import java.net.URL;
jjg@372: import java.net.URLClassLoader;
jjg@372: import java.util.ArrayList;
jjg@372: import java.util.jar.JarFile;
jjg@372: 
jjg@372: /**
jjg@372:  * A URLClassLoader that also implements Closeable.
jjg@372:  * Reflection is used to access internal data structures in the URLClassLoader,
jjg@372:  * since no public API exists for this purpose. Therefore this code is somewhat
jjg@372:  * fragile. Caveat emptor.
jjg@372:  * @throws Error if the internal data structures are not as expected.
jjg@372:  *
jjg@581:  *  <p><b>This is NOT part of any supported API.
jjg@581:  *  If you write code that depends on this, you do so at your own risk.
jjg@372:  *  This code and its internal interfaces are subject to change or
jjg@372:  *  deletion without notice.</b>
jjg@372:  */
jjg@450: public class CloseableURLClassLoader
jjg@372:         extends URLClassLoader implements Closeable {
jjg@450:     public CloseableURLClassLoader(URL[] urls, ClassLoader parent) throws Error {
jjg@372:         super(urls, parent);
jjg@372:         try {
jjg@372:             getLoaders(); //proactive check that URLClassLoader is as expected
jjg@372:         } catch (Throwable t) {
jjg@372:             throw new Error("cannot create CloseableURLClassLoader", t);
jjg@372:         }
jjg@372:     }
jjg@372: 
jjg@372:     /**
jjg@372:      * Close any jar files that may have been opened by the class loader.
jjg@372:      * Reflection is used to access the jar files in the URLClassLoader's
jjg@372:      * internal data structures.
jjg@372:      * @throws java.io.IOException if the jar files cannot be found for any
jjg@372:      * reson, or if closing the jar file itself causes an IOException.
jjg@372:      */
jjg@450:     @Override
jjg@372:     public void close() throws IOException {
jjg@372:         try {
jjg@372:             for (Object l: getLoaders()) {
jjg@372:                 if (l.getClass().getName().equals("sun.misc.URLClassPath$JarLoader")) {
jjg@372:                     Field jarField = l.getClass().getDeclaredField("jar");
jjg@372:                     JarFile jar = (JarFile) getField(l, jarField);
jjg@407:                     if (jar != null) {
jjg@407:                         //System.err.println("CloseableURLClassLoader: closing " + jar);
jjg@407:                         jar.close();
jjg@407:                     }
jjg@372:                 }
jjg@372:             }
jjg@372:         } catch (Throwable t) {
jjg@372:             IOException e = new IOException("cannot close class loader");
jjg@372:             e.initCause(t);
jjg@372:             throw e;
jjg@372:         }
jjg@372:     }
jjg@372: 
jjg@372:     private ArrayList<?> getLoaders()
jjg@372:             throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException
jjg@372:     {
jjg@372:         Field ucpField = URLClassLoader.class.getDeclaredField("ucp");
jjg@372:         Object urlClassPath = getField(this, ucpField);
jjg@372:         if (urlClassPath == null)
jjg@372:             throw new AssertionError("urlClassPath not set in URLClassLoader");
jjg@372:         Field loadersField = urlClassPath.getClass().getDeclaredField("loaders");
jjg@372:         return (ArrayList<?>) getField(urlClassPath, loadersField);
jjg@372:     }
jjg@372: 
jjg@372:     private Object getField(Object o, Field f)
jjg@372:             throws IllegalArgumentException, IllegalAccessException {
jjg@372:         boolean prev = f.isAccessible();
jjg@372:         try {
jjg@372:             f.setAccessible(true);
jjg@372:             return f.get(o);
jjg@372:         } finally {
jjg@372:             f.setAccessible(prev);
jjg@372:         }
jjg@372:     }
jjg@372: 
jjg@372: }