org.mycore.common.MCRClassTools Maven / Gradle / Ivy
/*
* This file is part of *** M y C o R e ***
* See http://www.mycore.de/ for details.
*
* MyCoRe 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 3 of the License, or
* (at your option) any later version.
*
* MyCoRe 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 MyCoRe. If not, see .
*/
package org.mycore.common;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Optional;
public class MCRClassTools {
private static volatile ClassLoader extendedClassLoader;
static {
updateClassLoader(); //first init
}
public static Object loadClassFromURL(String classPath, String className)
throws MalformedURLException, ReflectiveOperationException {
return loadClassFromURL(new File(classPath), className);
}
public static Object loadClassFromURL(File file, String className)
throws MalformedURLException, ReflectiveOperationException {
if (file.exists()) {
URL url = file.toURI().toURL();
URLClassLoader urlClassLoader = new URLClassLoader(new URL[] { url },
Thread.currentThread().getContextClassLoader());
Class clazz = urlClassLoader.loadClass(className);
return clazz.getDeclaredConstructor().newInstance();
}
return null;
}
/**
* Loads a class via default ClassLoader or Thread.currentThread().getContextClassLoader()
.
* @param classname Name of class
* @param Type of Class
* @return the initialized class
* @throws ClassNotFoundException if both ClassLoader cannot load the Class
*/
public static Class forName(String classname) throws ClassNotFoundException {
@SuppressWarnings("unchecked")
Class forName;
try {
forName = (Class) Class.forName(classname);
} catch (ClassNotFoundException cnfe) {
forName = (Class) Class.forName(classname, true, extendedClassLoader);
}
return forName;
}
/**
* @return a ClassLoader that should be used to load resources
*/
public static ClassLoader getClassLoader() {
return extendedClassLoader;
}
public static void updateClassLoader() {
extendedClassLoader = Optional.ofNullable(Thread.currentThread().getContextClassLoader())
.orElseGet(MCRClassTools.class::getClassLoader);
}
}