Java tutorial
package org.bimserver.plugins.classloaders; /****************************************************************************** * Copyright (C) 2009-2013 BIMserver.org * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. *****************************************************************************/ import java.io.ByteArrayInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.net.MalformedURLException; import java.net.URL; import java.net.URLConnection; import java.net.URLStreamHandler; import java.util.HashMap; import java.util.Map; import java.util.jar.JarEntry; import java.util.jar.JarInputStream; import java.util.zip.DeflaterOutputStream; import java.util.zip.InflaterInputStream; import org.apache.commons.io.IOUtils; import org.apache.commons.io.output.ByteArrayOutputStream; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class JarClassLoader extends ClassLoader { private static final Logger LOGGER = LoggerFactory.getLogger(JarClassLoader.class); private final File jarFile; private final Map<String, byte[]> map = new HashMap<String, byte[]>(); private final Map<String, Class<?>> loadedClasses = new HashMap<String, Class<?>>(); public JarClassLoader(ClassLoader parentClassLoader, File jarFile) throws FileNotFoundException, IOException { super(parentClassLoader); this.jarFile = jarFile; JarInputStream jarInputStream = new JarInputStream(new FileInputStream(jarFile)); JarEntry entry = jarInputStream.getNextJarEntry(); while (entry != null) { if (entry.getName().endsWith(".jar")) { ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); IOUtils.copy(jarInputStream, byteArrayOutputStream); // Not storing the original JAR, so future code will be unable to read the original loadSubJars(byteArrayOutputStream.toByteArray()); } else { // Files are being stored deflated in memory because most of the time a lot of files are not being used (or the complete plugin is not being used) addDataToMap(jarInputStream, entry); } entry = jarInputStream.getNextJarEntry(); } jarInputStream.close(); } private void addDataToMap(JarInputStream jarInputStream, JarEntry entry) throws IOException { ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream(); DeflaterOutputStream deflaterOutputStream = new DeflaterOutputStream(byteArrayOutputStream); IOUtils.copy(jarInputStream, deflaterOutputStream); deflaterOutputStream.finish(); map.put(entry.getName(), byteArrayOutputStream.toByteArray()); } private void loadSubJars(byte[] byteArray) { try { JarInputStream jarInputStream = new JarInputStream(new ByteArrayInputStream(byteArray)); JarEntry entry = jarInputStream.getNextJarEntry(); while (entry != null) { addDataToMap(jarInputStream, entry); entry = jarInputStream.getNextJarEntry(); } jarInputStream.close(); } catch (IOException e) { LOGGER.error("", e); } } @Override protected URL findResource(final String name) { if (map.containsKey(name)) { try { return new URL(new URL("jar:" + jarFile.toURI().toURL() + "!/" + name), name, new URLStreamHandler() { @Override protected URLConnection openConnection(URL u) throws IOException { return new URLConnection(u) { @Override public void connect() throws IOException { } @Override public InputStream getInputStream() throws IOException { return new InflaterInputStream(new ByteArrayInputStream(map.get(name))); } }; } }); } catch (MalformedURLException e) { LOGGER.error("", e); } } return null; } @Override protected Class<?> findClass(String name) throws ClassNotFoundException { String fileName = name.replace(".", "/") + ".class"; if (loadedClasses.containsKey(fileName)) { return loadedClasses.get(fileName); } if (map.containsKey(fileName)) { byte[] bs = map.get(fileName); InflaterInputStream inflaterInputStream = new InflaterInputStream(new ByteArrayInputStream(bs)); ByteArrayOutputStream uncompressed = new ByteArrayOutputStream(); try { IOUtils.copy(inflaterInputStream, uncompressed); } catch (IOException e) { e.printStackTrace(); } byte[] byteArray = uncompressed.toByteArray(); Class<?> defineClass = defineClass(name, byteArray, 0, byteArray.length); loadedClasses.put(fileName, defineClass); /* * This is a fix to actually load the package-info.class file with * the annotations about for example namespaces required for JAXB to * work. Found this code here: * https://issues.jboss.org/browse/JBPM-1404 */ if (defineClass != null) { final int packageIndex = name.lastIndexOf('.'); if (packageIndex != -1) { final String packageName = name.substring(0, packageIndex); final Package classPackage = getPackage(packageName); if (classPackage == null) { definePackage(packageName, null, null, null, null, null, null, null); } } } // The original class file cannot be loaded for other purposes after this (would be strange), this saves memory map.remove(fileName); return defineClass; } throw new ClassNotFoundException(name); } }