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