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/* * Copyright 2002-2017 the original author or authors. * * Licensed 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.springframework.instrument.classloading; import java.io.IOException; import java.io.InputStream; import java.lang.instrument.ClassFileTransformer; import java.lang.instrument.IllegalClassFormatException; import java.net.URL; import java.util.Enumeration; import java.util.HashMap; import java.util.LinkedList; import java.util.List; import java.util.Map; import org.springframework.core.DecoratingClassLoader; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.FileCopyUtils; import org.springframework.util.StringUtils; /** * ClassLoader decorator that shadows an enclosing ClassLoader, * applying registered transformers to all affected classes. * * @author Rob Harrop * @author Juergen Hoeller * @author Costin Leau * @since 2.0 * @see #addTransformer * @see org.springframework.core.OverridingClassLoader */ public class ShadowingClassLoader extends DecoratingClassLoader { /** Packages that are excluded by default */ public static final String[] DEFAULT_EXCLUDED_PACKAGES = new String[] { "java.", "javax.", "sun.", "oracle.", "com.sun.", "com.ibm.", "COM.ibm.", "org.w3c.", "org.xml.", "org.dom4j.", "org.eclipse", "org.aspectj.", "net.sf.cglib", "org.springframework.cglib", "org.apache.xerces.", "org.apache.commons.logging." }; private final ClassLoader enclosingClassLoader; private final List<ClassFileTransformer> classFileTransformers = new LinkedList<>(); private final Map<String, Class<?>> classCache = new HashMap<>(); /** * Create a new ShadowingClassLoader, decorating the given ClassLoader, * applying {@link #DEFAULT_EXCLUDED_PACKAGES}. * @param enclosingClassLoader the ClassLoader to decorate * @see #ShadowingClassLoader(ClassLoader, boolean) */ public ShadowingClassLoader(ClassLoader enclosingClassLoader) { this(enclosingClassLoader, true); } /** * Create a new ShadowingClassLoader, decorating the given ClassLoader. * @param enclosingClassLoader the ClassLoader to decorate * @param defaultExcludes whether to apply {@link #DEFAULT_EXCLUDED_PACKAGES} * @since 4.3.8 */ public ShadowingClassLoader(ClassLoader enclosingClassLoader, boolean defaultExcludes) { Assert.notNull(enclosingClassLoader, "Enclosing ClassLoader must not be null"); this.enclosingClassLoader = enclosingClassLoader; if (defaultExcludes) { for (String excludedPackage : DEFAULT_EXCLUDED_PACKAGES) { excludePackage(excludedPackage); } } } /** * Add the given ClassFileTransformer to the list of transformers that this * ClassLoader will apply. * @param transformer the ClassFileTransformer */ public void addTransformer(ClassFileTransformer transformer) { Assert.notNull(transformer, "Transformer must not be null"); this.classFileTransformers.add(transformer); } /** * Copy all ClassFileTransformers from the given ClassLoader to the list of * transformers that this ClassLoader will apply. * @param other the ClassLoader to copy from */ public void copyTransformers(ShadowingClassLoader other) { Assert.notNull(other, "Other ClassLoader must not be null"); this.classFileTransformers.addAll(other.classFileTransformers); } @Override public Class<?> loadClass(String name) throws ClassNotFoundException { if (shouldShadow(name)) { Class<?> cls = this.classCache.get(name); if (cls != null) { return cls; } return doLoadClass(name); } else { return this.enclosingClassLoader.loadClass(name); } } /** * Determine whether the given class should be excluded from shadowing. * @param className the name of the class * @return whether the specified class should be shadowed */ private boolean shouldShadow(String className) { return (!className.equals(getClass().getName()) && !className.endsWith("ShadowingClassLoader") && isEligibleForShadowing(className)); } /** * Determine whether the specified class is eligible for shadowing * by this class loader. * @param className the class name to check * @return whether the specified class is eligible * @see #isExcluded */ protected boolean isEligibleForShadowing(String className) { return !isExcluded(className); } private Class<?> doLoadClass(String name) throws ClassNotFoundException { String internalName = StringUtils.replace(name, ".", "/") + ".class"; InputStream is = this.enclosingClassLoader.getResourceAsStream(internalName); if (is == null) { throw new ClassNotFoundException(name); } try { byte[] bytes = FileCopyUtils.copyToByteArray(is); bytes = applyTransformers(name, bytes); Class<?> cls = defineClass(name, bytes, 0, bytes.length); // Additional check for defining the package, if not defined yet. if (cls.getPackage() == null) { int packageSeparator = name.lastIndexOf('.'); if (packageSeparator != -1) { String packageName = name.substring(0, packageSeparator); definePackage(packageName, null, null, null, null, null, null, null); } } this.classCache.put(name, cls); return cls; } catch (IOException ex) { throw new ClassNotFoundException("Cannot load resource for class [" + name + "]", ex); } } private byte[] applyTransformers(String name, byte[] bytes) { String internalName = StringUtils.replace(name, ".", "/"); try { for (ClassFileTransformer transformer : this.classFileTransformers) { byte[] transformed = transformer.transform(this, internalName, null, null, bytes); bytes = (transformed != null ? transformed : bytes); } return bytes; } catch (IllegalClassFormatException ex) { throw new IllegalStateException(ex); } } @Override public URL getResource(String name) { return this.enclosingClassLoader.getResource(name); } @Override @Nullable public InputStream getResourceAsStream(String name) { return this.enclosingClassLoader.getResourceAsStream(name); } @Override public Enumeration<URL> getResources(String name) throws IOException { return this.enclosingClassLoader.getResources(name); } }