Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.openejb.util.classloader; import org.apache.openejb.core.ParentClassLoaderFinder; import org.apache.openejb.loader.SystemInstance; import java.io.IOException; import java.net.URL; import java.net.URLClassLoader; import java.util.ArrayList; import java.util.Arrays; import java.util.Collection; import java.util.Collections; import java.util.Enumeration; import java.util.concurrent.locks.ReentrantLock; // TODO: look SM usage, find a better name public class URLClassLoaderFirst extends URLClassLoader { private static final ReentrantLock LOCK; // log4j is optional, moreover it will likely not work if not skipped and loaded by a temp classloader private static final boolean SKIP_LOG4J = "true".equals( SystemInstance.get().getProperty("openejb.skip.log4j", "true")) && skipLib("org.apache.log4j.Logger"); private static final boolean SKIP_MYFACES = "true" .equals(SystemInstance.get().getProperty("openejb.skip.myfaces", "true")) && skipLib("org.apache.myfaces.spi.FactoryFinderProvider"); private static final boolean SKIP_HSQLDB = skipLib("org.hsqldb.lib.HsqlTimer"); // commons-net is only in tomee-plus private static final boolean SKIP_COMMONS_NET = skipLib("org.apache.commons.net.pop3.POP3Client"); // first skip container APIs if not in the jaxrs or plus version private static final boolean SKIP_JAXWS = skipLib("org.apache.cxf.jaxws.support.JaxWsImplementorInfo"); private static final boolean SKIP_JMS = skipLib("org.apache.activemq.broker.BrokerFactory"); // - will not match anything, that's the desired default behavior public static final Collection<String> FORCED_SKIP = new ArrayList<>(); public static final Collection<String> FORCED_LOAD = new ArrayList<>(); static { LOCK = new ReentrantLock(); reloadConfig(); } public static final String SLF4J_BINDER_CLASS = "org/slf4j/impl/StaticLoggerBinder.class"; private static final URL SLF4J_CONTAINER = URLClassLoaderFirst.class.getClassLoader() .getResource(SLF4J_BINDER_CLASS); private static final String CLASS_EXT = ".class"; public static final ClassLoader SYSTEM_CLASS_LOADER = ClassLoader.getSystemClassLoader(); public static void reloadConfig() { list(FORCED_SKIP, "openejb.classloader.forced-skip"); list(FORCED_LOAD, "openejb.classloader.forced-load"); } private static void list(final Collection<String> list, final String key) { list.clear(); final String s = SystemInstance.get().getOptions().get(key, (String) null); if (s != null && !s.trim().isEmpty()) { list.addAll(Arrays.asList(s.trim().split(","))); } } private static boolean skipLib(final String includedClass) { try { URLClassLoaderFirst.class.getClassLoader().loadClass(includedClass); return "true".equalsIgnoreCase(System.getProperty(includedClass + ".skip", "true")); } catch (final ClassNotFoundException e) { return false; } } private final ClassLoader system; public URLClassLoaderFirst(final URL[] urls, final ClassLoader parent) { super(urls, parent); system = ClassLoader.getSystemClassLoader(); } @Override public Class<?> loadClass(final String name, final boolean resolve) throws ClassNotFoundException { final ReentrantLock lock = LOCK; lock.lock(); try { // already loaded? Class<?> clazz = findLoadedClass(name); if (clazz != null) { if (resolve) { resolveClass(clazz); } return clazz; } // JSE classes? if (canBeLoadedFromSystem(name)) { try { clazz = system.loadClass(name); if (clazz != null) { if (resolve) { resolveClass(clazz); } return clazz; } } catch (final ClassNotFoundException ignored) { // no-op } } // look for it in this classloader final boolean ok = !(shouldSkip(name) || shouldDelegateToTheContainer(this, name)); if (ok) { clazz = loadInternal(name, resolve); if (clazz != null) { return clazz; } } // finally delegate clazz = loadFromParent(name, resolve); if (clazz != null) { return clazz; } if (!ok) { clazz = loadInternal(name, resolve); if (clazz != null) { return clazz; } } throw new ClassNotFoundException(name); } finally { lock.unlock(); } } public static boolean shouldDelegateToTheContainer(final ClassLoader loader, final String name) { return shouldSkipJsf(loader, name) || shouldSkipSlf4j(loader, name); } private Class<?> loadFromParent(final String name, final boolean resolve) { ClassLoader parent = getParent(); if (parent == null) { parent = system; } try { final Class<?> clazz = Class.forName(name, false, parent); if (clazz != null) { if (resolve) { resolveClass(clazz); } return clazz; } } catch (final ClassNotFoundException ignored) { // no-op } return null; } private Class<?> loadInternal(final String name, final boolean resolve) { try { final Class<?> clazz = findClass(name); if (clazz != null) { if (resolve) { resolveClass(clazz); } return clazz; } } catch (final ClassNotFoundException ignored) { // no-op } return null; } // we skip webapp enrichment jars since we want to load them from the webapp or lib // Note: this is not a real limitation since it is first fail it will be done later public static boolean canBeLoadedFromSystem(final String name) { return !name.startsWith("org.apache.openejb.") || !isWebAppEnrichment(name.substring("org.apache.openejb.".length())); } // making all these call inline if far more costly than factorizing packages // // /!\ please check org.apache.openejb.persistence.PersistenceUnitInfoImpl.isServerClass() too // when updating this method public static boolean shouldSkip(final String name) { if (name == null) { // can happen with rest servlet definition or errors return false; } for (final String prefix : FORCED_SKIP) { if (name.startsWith(prefix)) { return true; } } for (final String prefix : FORCED_LOAD) { if (name.startsWith(prefix)) { return false; } } if (name.startsWith("java.")) { return true; } if (name.startsWith("javax.faces.")) { return false; } if (name.startsWith("javax.mail.")) { return false; } if (name.startsWith("javax.")) { return isInServer(name); } if (name.startsWith("sun.")) { return isInJvm(name); } // can be provided in the webapp if (name.startsWith("javax.servlet.jsp.jstl")) { return false; } if (name.startsWith("org.")) { final String org = name.substring("org.".length()); if (org.startsWith("apache.")) { final String apache = org.substring("apache.".length()); // the following block is classes which enrich webapp classloader if (apache.startsWith("webbeans.jsf")) { return false; } if (apache.startsWith("tomee.mojarra.")) { return false; } // here we find server classes if (apache.startsWith("bval.")) { return true; } if (apache.startsWith("openjpa.")) { return true; } if (apache.startsWith("xbean.")) { return !apache.substring("xbean.".length()).startsWith("spring"); } if (apache.startsWith("geronimo.")) { return true; } if (apache.startsWith("coyote.")) { return true; } if (apache.startsWith("webbeans.")) { return true; } if (apache.startsWith("log4j.") && SKIP_LOG4J) { return true; } if (apache.startsWith("catalina.")) { return true; } if (apache.startsWith("jasper.")) { return true; } if (apache.startsWith("tomcat.")) { return true; } if (apache.startsWith("el.")) { return true; } // if (apache.startsWith("jsp")) return true; // precompiled jsp have to be loaded from the webapp if (apache.startsWith("naming.")) { return true; } if (apache.startsWith("taglibs.")) { return true; } if (apache.startsWith("openejb.")) { // skip all excepted webapp enrichment artifacts return !isWebAppEnrichment(apache.substring("openejb.".length())); } if (apache.startsWith("commons.")) { final String commons = apache.substring("commons.".length()); // don't stop on commons package since we don't bring all commons if (commons.startsWith("beanutils.")) { return isInServer(name); } if (commons.startsWith("cli.")) { return true; } if (commons.startsWith("codec.")) { return true; } if (commons.startsWith("collections.")) { return true; } if (commons.startsWith("dbcp.")) { return true; } if (commons.startsWith("digester.")) { return true; } if (commons.startsWith("jocl.")) { return true; } if (commons.startsWith("lang.")) { // openjpa return true; } if (commons.startsWith("lang3.")) { // us return true; } if (commons.startsWith("logging.")) { return false; } if (commons.startsWith("pool.")) { return true; } if (commons.startsWith("net.") && SKIP_COMMONS_NET) { return true; } return false; } if (SKIP_MYFACES && apache.startsWith("myfaces.")) { // we bring only myfaces-impl (+api but that's javax) // mainly inspired from a comparison with tomahawk packages final String myfaces = name.substring("myfaces.".length()); if (myfaces.startsWith("shared.")) { return true; } if (myfaces.startsWith("ee6.")) { return true; } if (myfaces.startsWith("lifecycle.")) { return true; } if (myfaces.startsWith("context.")) { return true; } if (myfaces.startsWith("logging.")) { return true; } // tomahawk uses component.html package if (myfaces.startsWith("component.visit.") || myfaces.equals("component.ComponentResourceContainer")) { return true; } if (myfaces.startsWith("application.")) { return true; } if (myfaces.startsWith("config.")) { return true; } if (myfaces.startsWith("event.")) { return true; } if (myfaces.startsWith("resource.")) { return true; } if (myfaces.startsWith("el.")) { return true; } if (myfaces.startsWith("spi.")) { return true; } if (myfaces.startsWith("convert.")) { return true; } if (myfaces.startsWith("debug.")) { return true; } if (myfaces.startsWith("util.")) { return true; } if (myfaces.startsWith("view.")) { return true; } if (myfaces.equals("convert.ConverterUtils")) { return true; } if (myfaces.startsWith("renderkit.")) { final String renderkit = myfaces.substring("renderkit.".length()); if (renderkit.startsWith("html.Html")) { return true; } final char firstNextletter = renderkit.charAt(0); if (Character.isUpperCase(firstNextletter)) { return true; } return false; } if (myfaces.startsWith("taglib.")) { final String taglib = myfaces.substring("taglib.".length()); if (taglib.startsWith("html.Html")) { return true; } if (taglib.startsWith("core.")) { return true; } return false; } if (myfaces.startsWith("webapp.")) { final String webapp = myfaces.substring("webapp.".length()); if (webapp.startsWith("Faces")) { return true; } if (webapp.startsWith("Jsp")) { return true; } if (webapp.startsWith("Startup")) { return true; } if (webapp.equals("AbstractFacesInitializer")) { return true; } if (webapp.equals("MyFacesServlet")) { return true; } if (webapp.equals("ManagedBeanDestroyerListener")) { return true; } if (webapp.equals("WebConfigParamsLogger")) { return true; } return false; } return false; } if (apache.startsWith("activemq.")) { return SKIP_JMS && isInServer(name); } return false; } // other org packages if (org.startsWith("hsqldb.") && SKIP_HSQLDB) { return true; } if (org.startsWith("codehaus.swizzle.")) { final String swizzle = org.substring("codehaus.swizzle.".length()); if (swizzle.startsWith("stream.")) { return true; } if (swizzle.startsWith("rss.")) { return true; } if (swizzle.startsWith("Grep.class") || swizzle.startsWith("Lexer.class")) { return true; } return false; } if (org.startsWith("w3c.dom.") || org.startsWith("xml.sax.")) { return isInJvm(name); } if (org.startsWith("eclipse.jdt.")) { return true; } // let an app use its own slf4j impl (so its own api too) // if (org.startsWith("slf4j")) return true; return false; } // other packages if (name.startsWith("com.sun.")) { return isInJvm(name); } if (name.startsWith("serp.bytecode.")) { return true; } return false; } private static boolean isInJvm(final String name) { return SYSTEM_CLASS_LOADER.getResource(name.replace('.', '/') + CLASS_EXT) != null; } private static boolean isInServer(final String name) { if (name.startsWith("javax.")) { final String sub = name.substring("javax.".length()); if (sub.startsWith("jws.")) { return SKIP_JAXWS; } if (sub.startsWith("jms.")) { return SKIP_JMS; } } return ParentClassLoaderFinder.Helper.get().getResource(name.replace('.', '/') + ".class") != null; } public static boolean shouldSkipJsf(final ClassLoader loader, final String name) { if (!name.startsWith("javax.faces.")) { return false; } // using annotation to test to avoid to load more classes with deps final String testClass; if ("javax.faces.bean.RequestScoped".equals(name)) { testClass = "javax.faces.bean.SessionScoped"; } else { testClass = "javax.faces.bean.RequestScoped"; } final String classname = testClass.replace('.', '/') + ".class"; try { final Enumeration<URL> resources = loader.getResources(classname); final Collection<URL> thisJSf = Collections.list(resources); return thisJSf.isEmpty() || thisJSf.size() <= 1; } catch (final IOException e) { return true; } } // in org.apache.openejb. private static boolean isWebAppEnrichment(final String openejb) { return openejb.startsWith("hibernate.") || openejb.startsWith("jpa.integration.") || openejb.startsWith("toplink.") || openejb.startsWith("eclipselink.") || openejb.startsWith("arquillian."); } @Override public Enumeration<URL> getResources(final String name) throws IOException { return URLClassLoaderFirst.filterResources(name, super.getResources(name)); } public static boolean isFilterableResource(final String name) { // currently bean validation, Slf4j, myfaces (because of enrichment) return name != null && ("META-INF/services/javax.validation.spi.ValidationProvider".equals(name) || name.startsWith("META-INF/services/org.apache.myfaces.spi") || SLF4J_BINDER_CLASS.equals(name)); } public static boolean shouldSkipSlf4j(final ClassLoader loader, final String name) { if (name == null || !name.startsWith("org.slf4j.")) { return false; } try { // using getResource here just returns randomly the container one so we need getResources final Enumeration<URL> resources = loader.getResources(SLF4J_BINDER_CLASS); while (resources.hasMoreElements()) { final URL resource = resources.nextElement(); if (!resource.equals(SLF4J_CONTAINER)) { // applicative slf4j return false; } } } catch (final Throwable e) { // no-op } return true; } // useful method for SPI public static Enumeration<URL> filterResources(final String name, final Enumeration<URL> result) { if (isFilterableResource(name)) { final Collection<URL> values = Collections.list(result); if (values.size() > 1) { // remove openejb one final URL url = URLClassLoaderFirst.class.getResource("/" + name); if (url != null) { values.remove(url); } } return Collections.enumeration(values); } return result; } }