/*
* Copyright 2013 Google Inc. All Rights Reserved.
* 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 com.google.appengine.tck.transformers;
import java.io.ByteArrayInputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
import java.util.logging.Logger;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtMethod;
import javassist.LoaderClassPath;
import javassist.bytecode.AnnotationsAttribute;
import javassist.bytecode.AttributeInfo;
import javassist.bytecode.ClassFile;
import javassist.bytecode.ConstPool;
import javassist.bytecode.annotation.Annotation;
/**
* @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a>
*/
public abstract class JavassistTransformer implements ClassFileTransformer {
protected Logger log = Logger.getLogger(getClass().getName());
public byte[] transform(final ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
final ClassLoader previous = Thread.currentThread().getContextClassLoader();
Thread.currentThread().setContextClassLoader(loader);
try {
ClassPool pool = new ClassPool();
pool.appendClassPath(new LoaderClassPath(loader));
CtClass clazz = pool.makeClass(new ByteArrayInputStream(classfileBuffer));
if (isAlreadyTransformed(clazz) == false) {
log.info("Transforming " + className + " with " + getClass().getSimpleName());
transform(clazz);
} else {
log.fine(className + " is already transformed with " + getClass().getSimpleName());
}
return clazz.toBytecode();
} catch (Exception e) {
throw new IllegalClassFormatException(e.getMessage());
} finally {
Thread.currentThread().setContextClassLoader(previous);
}
}
protected abstract boolean isAlreadyTransformed(CtClass clazz) throws Exception;
protected abstract void transform(CtClass clazz) throws Exception;
protected static Class<?> loadClas(CtClass clazz, String annotationClassname) throws ClassNotFoundException {
return clazz.getClassPool().getClassLoader().loadClass(annotationClassname);
}
protected static void addAnnotation(CtClass clazz, CtMethod method, String annotationClassName) throws Exception {
ClassFile ccFile = clazz.getClassFile();
ConstPool constPool = ccFile.getConstPool();
AttributeInfo info = method.getMethodInfo().getAttribute(AnnotationsAttribute.visibleTag);
AnnotationsAttribute attr;
if (info == null) {
attr = new AnnotationsAttribute(constPool, AnnotationsAttribute.visibleTag);
} else {
attr = AnnotationsAttribute.class.cast(info);
}
constPool.addUtf8Info(annotationClassName);
Annotation annotation = new Annotation(annotationClassName, constPool);
attr.addAnnotation(annotation);
method.getMethodInfo().addAttribute(attr);
}
}