com.toolazydogs.maiden.agent.IronTransformer.java Source code

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Here is the source code for com.toolazydogs.maiden.agent.IronTransformer.java

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/**
 *
 * Copyright 2010-2011 (C) 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 com.toolazydogs.maiden.agent;

import java.io.PrintWriter;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;
import java.util.logging.Logger;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.util.TraceClassVisitor;

import com.toolazydogs.maiden.agent.api.Dispatcher;

/**
 * The root class transformer for the iron maiden agent.  This class is a
 * simple wrapper to a dispatcher.
 */
public final class IronTransformer implements ClassFileTransformer, Opcodes {
    private final static String CLASS_NAME = IronTransformer.class.getName();
    private final static Logger LOGGER = Logger.getLogger(CLASS_NAME);
    private final Dispatcher dispatcher;
    private final boolean nativeMethodPrefixSupported;

    public IronTransformer(Dispatcher dispatcher) {
        this(dispatcher, false);
    }

    public IronTransformer(Dispatcher dispatcher, boolean nativeMethodPrefixSupported) {
        assert dispatcher != null;

        this.dispatcher = dispatcher;
        this.nativeMethodPrefixSupported = nativeMethodPrefixSupported;
    }

    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
            ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
        byte[] results = new byte[0];
        try {
            LOGGER.entering(CLASS_NAME, "transform",
                    new Object[] { loader, className, classBeingRedefined, protectionDomain, classfileBuffer });

            ClassFileTransformer transformer = dispatcher.lookup(loader, className, classBeingRedefined,
                    protectionDomain, nativeMethodPrefixSupported);

            results = transformer.transform(loader, className, classBeingRedefined, protectionDomain,
                    classfileBuffer);

            //            System.err.println("TRANSFORMED " + className);
            if ("java/lang/reflect/Proxy".equals(className)) {
                print(classfileBuffer);
                print(results);
            }

            LOGGER.exiting(CLASS_NAME, "transform", results);
        } catch (Throwable e) {
            e.printStackTrace(); //Todo change body of catch statement use File | Settings | File Templates.
        }

        return results;
    }

    private static void print(byte[] b) {
        ClassReader reader = new ClassReader(b);
        reader.accept(new TraceClassVisitor(null, new PrintWriter(System.out)), ClassReader.EXPAND_FRAMES);
    }
}