org.springframework.instrument.classloading.websphere.WebSphereClassPreDefinePlugin Maven / Gradle / Ivy
/*
* Copyright 2002-2012 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.websphere;
import java.lang.instrument.ClassFileTransformer;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.security.CodeSource;
import org.springframework.util.FileCopyUtils;
/**
* Adapter that implements WebSphere 7.0 ClassPreProcessPlugin interface,
* delegating to a standard JDK {@link ClassFileTransformer} underneath.
*
* To avoid compile time checks again the vendor API, a dynamic proxy is
* being used.
*
* @author Costin Leau
* @since 3.1
*/
class WebSphereClassPreDefinePlugin implements InvocationHandler {
private final ClassFileTransformer transformer;
/**
* Create a new {@link WebSphereClassPreDefinePlugin}.
* @param transformer the {@link ClassFileTransformer} to be adapted
* (must not be {@code null})
*/
public WebSphereClassPreDefinePlugin(ClassFileTransformer transformer) {
this.transformer = transformer;
ClassLoader classLoader = transformer.getClass().getClassLoader();
// first force the full class loading of the weaver by invoking transformation on a dummy class
try {
String dummyClass = Dummy.class.getName().replace('.', '/');
byte[] bytes = FileCopyUtils.copyToByteArray(classLoader.getResourceAsStream(dummyClass + ".class"));
transformer.transform(classLoader, dummyClass, null, null, bytes);
}
catch (Throwable ex) {
throw new IllegalArgumentException("Cannot load transformer", ex);
}
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String name = method.getName();
if ("equals".equals(name)) {
return (proxy == args[0]);
}
else if ("hashCode".equals(name)) {
return hashCode();
}
else if ("toString".equals(name)) {
return toString();
}
else if ("transformClass".equals(name)) {
return transform((String) args[0], (byte[]) args[1], (CodeSource) args[2], (ClassLoader) args[3]);
}
else {
throw new IllegalArgumentException("Unknown method: " + method);
}
}
protected byte[] transform(String className, byte[] classfileBuffer, CodeSource codeSource, ClassLoader classLoader)
throws Exception {
// NB: WebSphere passes className as "." without class while the transformer expects a VM, "/" format
byte[] result = transformer.transform(classLoader, className.replace('.', '/'), null, null, classfileBuffer);
return (result != null ? result : classfileBuffer);
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder(getClass().getName());
builder.append(" for transformer: ");
builder.append(this.transformer);
return builder.toString();
}
private static class Dummy {
}
}