TomcatInstrumentableClassLoader supports Tomcat 7.0.63+ as well

Issue: SPR-13210

Author: jhoeller

build.gradle

@@ -448,6 +448,10 @@ project("spring-instrument-tomcat") {
 	dependencies {
 		provided("org.apache.tomcat:catalina:6.0.16")
 	}
+
+	jar {
+		exclude("org/apache/**")  // exclude the mock used to bridge between pre-7.0.63 and 7.0.63+
+	}
 }
 
 project("spring-context") {

spring-instrument-tomcat/src/main/java/org/apache/catalina/loader/WebappClassLoader.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2002-2015 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.apache.catalina.loader;
+
+/**
+ * A mock of Tomcat's {@code WebappClassLoader} just for Spring's compilation purposes.
+ * Exposes both pre-7.0.63 as well as 7.0.63+ variants of {@code findResourceInternal}.
+ *
+ * @author Juergen Hoeller
+ * @since 4.2
+ */
+public class WebappClassLoader extends ClassLoader {
+
+	public WebappClassLoader() {
+	}
+
+	public WebappClassLoader(ClassLoader parent) {
+		super(parent);
+	}
+
+
+	protected ResourceEntry findResourceInternal(String name, String path) {
+		throw new UnsupportedOperationException();
+	}
+
+	protected ResourceEntry findResourceInternal(String name, String path, boolean manifestRequired) {
+		throw new UnsupportedOperationException();
+	}
+
+}

spring-instrument-tomcat/src/main/java/org/springframework/instrument/classloading/tomcat/TomcatInstrumentableClassLoader.java

@@ -44,7 +44,7 @@
  * in the LoadTimeWeaver interface, as expected by ReflectiveLoadTimeWeaver.
  *
  * <p><b>NOTE:</b> Requires Apache Tomcat version 6.0 or higher, as of Spring 4.0.
- * This class does not work on Tomcat 7.0.63 and higher; please rely on Tomcat's own
+ * This class is not intended to work on Tomcat 8.0+; please rely on Tomcat's own
  * {@code InstrumentableClassLoader} facility instead, as autodetected by Spring's
  * {@link org.springframework.instrument.classloading.tomcat.TomcatLoadTimeWeaver}.
  *
@@ -109,7 +109,7 @@ public ClassLoader getThrowawayClassLoader() {
 	}
 
 
-	@Override
+	@Override  // overriding the pre-7.0.63 variant of findResourceInternal
 	protected ResourceEntry findResourceInternal(String name, String path) {
 		ResourceEntry entry = super.findResourceInternal(name, path);
 		if (entry != null && entry.binaryContent != null && path.endsWith(CLASS_SUFFIX)) {
@@ -119,11 +119,19 @@ protected ResourceEntry findResourceInternal(String name, String path) {
 		return entry;
 	}
 
+	@Override  // overriding the 7.0.63+ variant of findResourceInternal
+	protected ResourceEntry findResourceInternal(String name, String path, boolean manifestRequired) {
+		ResourceEntry entry = super.findResourceInternal(name, path, manifestRequired);
+		if (entry != null && entry.binaryContent != null && path.endsWith(CLASS_SUFFIX)) {
+			String className = (name.endsWith(CLASS_SUFFIX) ? name.substring(0, name.length() - CLASS_SUFFIX.length()) : name);
+			entry.binaryContent = this.weavingTransformer.transformIfNecessary(className, entry.binaryContent);
+		}
+		return entry;
+	}
+
 	@Override
 	public String toString() {
-		StringBuilder sb = new StringBuilder(getClass().getName());
-		sb.append("\r\n").append(super.toString());
-		return sb.toString();
+		return getClass().getName() + "\r\n" + super.toString();
 	}
 
 

src/asciidoc/core-aop.adoc

@@ -3451,10 +3451,9 @@ Tomcat 6.0 and above.
 
 [TIP]
 ====
-Do not define `TomcatInstrumentableClassLoader` anymore as of Tomcat 7.0.44+ / 8.0.
+Do not define `TomcatInstrumentableClassLoader` anymore on Tomcat 8.0 and higher.
 Instead, let Spring automatically use Tomcat's new native `InstrumentableClassLoader`
-facility through the `TomcatLoadTimeWeaver` strategy, in particular on Tomcat 7.0.63+
-where `TomcatInstrumentableClassLoader` does not work at all anymore.
+facility through the `TomcatLoadTimeWeaver` strategy.
 ====
 
 If you still need to use `TomcatInstrumentableClassLoader`, it can be registered