On Demand ClassFileTransformer

OnDemandCFT.groovy

import org.codehaus.groovy.control.*
import org.codehaus.groovy.ast.ClassHelper;
import org.helios.gmx.classloading.*;
// Acquire the instrumentation instance
def instrumentation  = ByteCodeRepository.getInstance().agentInstrumentation.getInstrumentation();
// Define a closre
foo = {message -> println message};
// Define a simple class file transformer
class ByteCodeNet implements java.lang.instrument.ClassFileTransformer {
    def clazzName;
    def bytecode;
    public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, java.security.ProtectionDomain protectionDomain, byte[] classfileBuffer) {
        if(clazzName.equals(className)) {
            bytecode = classfileBuffer;
        }
        return classfileBuffer;
    }
}
// Instantiate class file transformer
cft = new ByteCodeNet(clazzName: foo.getClass().getName());
// Holder for our bytecode
def bytecode = null;
try {
    // Register the class file transformer with the instrumentation
    instrumentation.addTransformer(cft, true);
    // Direct the instrumentation to retransform the closure class
    instrumentation.retransformClasses(foo.getClass());
    // Grab the byte code from the class file transformer
    bytecode = cft.bytecode;
} finally {
    // Unregister the class file transformer
    instrumentation.removeTransformer(cft);
}
// Voila
println "Class:${foo.getClass().getName()}  Bytes:${bytecode.length}";