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113 lines
4.7 KiB
113 lines
4.7 KiB
// serverClassLoader.java
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// -----------------------
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// (C) by Michael Peter Christen; mc@yacy.net
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// first published on http://www.anomic.de
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// Frankfurt, Germany, 2004
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// last major change: 11.07.2004
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package net.yacy.server;
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import java.io.File;
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import java.io.IOException;
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import net.yacy.cora.util.ConcurrentLog;
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import net.yacy.kelondro.util.FileUtils;
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import net.yacy.search.Switchboard;
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import net.yacy.search.SwitchboardConstants;
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/**
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* Class loader for servlet classes
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* (findClass looking in default htroot directory)
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*/
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public final class serverClassLoader extends ClassLoader {
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public serverClassLoader() {
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//super(ClassLoader.getSystemClassLoader());
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super(Thread.currentThread().getContextClassLoader());
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if (!registerAsParallelCapable()) { // avoid blocking
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ConcurrentLog.warn("ClassLoader", "registerAsParallelCapable failed");
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}
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}
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public serverClassLoader(final ClassLoader parent) {
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super(parent);
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if (!registerAsParallelCapable()) {
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ConcurrentLog.warn("ClassLoader", "registerAsParallelCapable failed");
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}
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}
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/**
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* Find servlet class in default htroot directory
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* but use the internal loadClass(File) methode to load the class same way
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* (e.g. caching) as direct call to loadClass(File)
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* This methode is mainly to avoid classpath conflicts for servlet to servlet calls
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* making inclusion of htroot in system classpath not crucial
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*
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* @param classname (delivered by parent loader without ".class" file extension
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* @return class in htroot
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* @throws ClassNotFoundException
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*/
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@Override
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protected Class<?> findClass(String classname) throws ClassNotFoundException {
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// construct path to htroot for a servletname
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File cpath = new File (Switchboard.getSwitchboard().getAppPath(SwitchboardConstants.HTROOT_PATH, SwitchboardConstants.HTROOT_PATH_DEFAULT),classname+".class");
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return loadClass(cpath);
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}
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/**
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* A special loadClass using file as argument to find and load a class
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* This method is directly called by the application and not part of the
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* normal loadClass chain (= never called by JVM)
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*
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* @param classfile
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* @return loaded an resolved class
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* @throws ClassNotFoundException
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*/
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public Class<?> loadClass(final File classfile) throws ClassNotFoundException {
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Class<?> c;
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final int p = classfile.getName().indexOf('.',0);
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if (p < 0) throw new ClassNotFoundException("wrong class name: " + classfile.getName());
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final String classname = classfile.getName().substring(0, p);
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synchronized (this) {
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/* Important : we must first synchronize any concurrent access AND then check if the class was not already loaded.
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* Otherwise, trying to define again the same class (with the defineClass function) may lead to a JVM crash on some platforms,
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* notably when running on Java 11 (on earlier JVMs, a LinkageError was only triggered and gracefully catched in that case) */
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c = findLoadedClass(classname);
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if (c != null) {
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return c;
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}
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// load the file from the file system
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byte[] b;
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try {
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b = FileUtils.read(classfile);
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// make a class out of the stream
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c = this.defineClass(null, b, 0, b.length);
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resolveClass(c);
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} catch (final LinkageError ee) {
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/* This error could occur when two threads try to define concurrently the same class. Should not occur here */
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throw new ClassNotFoundException("linkageError, " + ee.getMessage() + ":" + classfile.toString());
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} catch (final IOException ee) {
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throw new ClassNotFoundException(ee.getMessage() + ":" + classfile.toString());
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}
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return c;
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}
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}
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} |