ByteCodeTransformer.java

package com.jsonde.instrumentation;

import com.jsonde.util.ClassUtils;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;

import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.security.ProtectionDomain;

public class ByteCodeTransformer implements ClassFileTransformer {

    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {

        className = ClassUtils.getFullyQualifiedName(className);

        if (Object.class.getName().equals(className))
            throw new RuntimeException();

        if (
                className.startsWith("com.jsonde") &&
                        !className.contains(".samples.")) {
            return classfileBuffer;
        }

        /*if (
                className.startsWith("sun.reflect")) {
            return classfileBuffer;
        }*/

        try {
            return transform(classfileBuffer, true, loader, classBeingRedefined);
        } catch (SkipClassException e) {
            e.printStackTrace();
            return classfileBuffer;
        } catch (ByteCodeTransformException e) {
            e.printStackTrace();
            throw new IllegalClassFormatException(e.getMessage());
        }
    }

    public byte[] transform(byte[] originalBytes, boolean instrumentClass, ClassLoader loader, Class<?> classBeingRedefined) throws ByteCodeTransformException {

        return transform(
                originalBytes,
                0,
                originalBytes.length,
                instrumentClass,
                loader,
                classBeingRedefined);

    }

    public byte[] transform(byte[] originalBytes, int offset, int length, boolean instrumentClass, ClassLoader classLoader, Class<?> classBeingRedefined) throws ByteCodeTransformException {

        try {

            ClassReader classReader = new ClassReader(originalBytes, offset, length);

            ClassWriter classWriter = new ClassWriter(classReader, ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

            ClassVisitor classVisitor;
            classVisitor = new JSondeClassTransformer(classWriter, instrumentClass, classLoader, classBeingRedefined);

            classReader.accept(classVisitor, ClassReader.EXPAND_FRAMES);


            final byte[] bytes = classWriter.toByteArray();
            /*dumpBytes(originalBytes);
            dumpBytes(bytes);*/

            return bytes;

        } catch (SkipClassException e) {
            e.printStackTrace();
            return originalBytes;
            //throw new ByteCodeTransformException(e); // todo fix
        }

    }

}