001/* 002 * Copyright 2002-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.instrument.classloading.tomcat; 018 019import java.lang.instrument.ClassFileTransformer; 020import java.lang.reflect.InvocationTargetException; 021import java.lang.reflect.Method; 022 023import org.springframework.core.OverridingClassLoader; 024import org.springframework.instrument.classloading.LoadTimeWeaver; 025import org.springframework.util.Assert; 026import org.springframework.util.ClassUtils; 027 028/** 029 * {@link org.springframework.instrument.classloading.LoadTimeWeaver} implementation 030 * for Tomcat's new {@code org.apache.tomcat.InstrumentableClassLoader}. 031 * Also capable of handling Spring's TomcatInstrumentableClassLoader when encountered. 032 * 033 * @author Juergen Hoeller 034 * @since 4.0 035 */ 036public class TomcatLoadTimeWeaver implements LoadTimeWeaver { 037 038 private static final String INSTRUMENTABLE_LOADER_CLASS_NAME = "org.apache.tomcat.InstrumentableClassLoader"; 039 040 041 private final ClassLoader classLoader; 042 043 private final Method addTransformerMethod; 044 045 private final Method copyMethod; 046 047 048 public TomcatLoadTimeWeaver() { 049 this(ClassUtils.getDefaultClassLoader()); 050 } 051 052 public TomcatLoadTimeWeaver(ClassLoader classLoader) { 053 Assert.notNull(classLoader, "ClassLoader must not be null"); 054 this.classLoader = classLoader; 055 056 Class<?> instrumentableLoaderClass; 057 try { 058 instrumentableLoaderClass = classLoader.loadClass(INSTRUMENTABLE_LOADER_CLASS_NAME); 059 if (!instrumentableLoaderClass.isInstance(classLoader)) { 060 // Could still be a custom variant of a convention-compatible ClassLoader 061 instrumentableLoaderClass = classLoader.getClass(); 062 } 063 } 064 catch (ClassNotFoundException ex) { 065 // We're on an earlier version of Tomcat, probably with Spring's TomcatInstrumentableClassLoader 066 instrumentableLoaderClass = classLoader.getClass(); 067 } 068 069 try { 070 this.addTransformerMethod = instrumentableLoaderClass.getMethod("addTransformer", ClassFileTransformer.class); 071 // Check for Tomcat's new copyWithoutTransformers on InstrumentableClassLoader first 072 Method copyMethod = ClassUtils.getMethodIfAvailable(instrumentableLoaderClass, "copyWithoutTransformers"); 073 if (copyMethod == null) { 074 // Fallback: expecting TomcatInstrumentableClassLoader's getThrowawayClassLoader 075 copyMethod = instrumentableLoaderClass.getMethod("getThrowawayClassLoader"); 076 } 077 this.copyMethod = copyMethod; 078 } 079 catch (Throwable ex) { 080 throw new IllegalStateException( 081 "Could not initialize TomcatLoadTimeWeaver because Tomcat API classes are not available", ex); 082 } 083 } 084 085 086 @Override 087 public void addTransformer(ClassFileTransformer transformer) { 088 try { 089 this.addTransformerMethod.invoke(this.classLoader, transformer); 090 } 091 catch (InvocationTargetException ex) { 092 throw new IllegalStateException("Tomcat addTransformer method threw exception", ex.getCause()); 093 } 094 catch (Throwable ex) { 095 throw new IllegalStateException("Could not invoke Tomcat addTransformer method", ex); 096 } 097 } 098 099 @Override 100 public ClassLoader getInstrumentableClassLoader() { 101 return this.classLoader; 102 } 103 104 @Override 105 public ClassLoader getThrowawayClassLoader() { 106 try { 107 return new OverridingClassLoader(this.classLoader, (ClassLoader) this.copyMethod.invoke(this.classLoader)); 108 } 109 catch (InvocationTargetException ex) { 110 throw new IllegalStateException("Tomcat copy method threw exception", ex.getCause()); 111 } 112 catch (Throwable ex) { 113 throw new IllegalStateException("Could not invoke Tomcat copy method", ex); 114 } 115 } 116 117}