org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver Maven / Gradle / Ivy
/*
* Copyright 2002-2006 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.lang.instrument.ClassFileTransformer;
import java.lang.instrument.Instrumentation;
import org.springframework.instrument.InstrumentationSavingAgent;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* Load time weaver relying on Instrumentation.
* Start with java agent, with JVM options like:
*
* -javaagent:path/to/spring-agent.jar
*
* where spring-agent.jar is a JAR file
* containing the InstrumentationSavingAgent class.
*
* In Eclipse, for example, set the Run configuration's JVM
* args to be of the form:
*
* -javaagent:${project_loc}/lib/spring-agent.jar
*
*
* @author Rod Johnson
* @since 2.0
* @see InstrumentationSavingAgent
*/
public class InstrumentationLoadTimeWeaver implements LoadTimeWeaver {
public void addTransformer(ClassFileTransformer transformer) {
Assert.notNull(transformer, "Transformer must not be null");
Instrumentation instrumentation = InstrumentationSavingAgent.getInstrumentation();
if (instrumentation == null) {
throw new IllegalStateException(
"Must start with Java agent to use InstrumentationLoadTimeWeaver. See Spring documentation.");
}
instrumentation.addTransformer(transformer);
}
/**
* We have the ability to weave the current class loader when starting the
* JVM in this way, so the instrumentable class loader will always be the
* current loader.
*/
public ClassLoader getInstrumentableClassLoader() {
return ClassUtils.getDefaultClassLoader();
}
/**
* This implementation always returns a SimpleThrowawayClassLoader.
* @see SimpleThrowawayClassLoader
*/
public ClassLoader getThrowawayClassLoader() {
return new SimpleThrowawayClassLoader(getInstrumentableClassLoader());
}
}