Example from http://code.google.com/p/jsr292-cookbook/source/browse/trunk/lazy-init/src/jsr292/cookbook/lazyinit/ ported to Rhino Class writer

Gen.java

package jsr292.cookbook.lazyinit;

import sun.misc.BASE64Encoder;

import java.io.IOException;
import java.lang.invoke.CallSite;
import java.lang.invoke.MethodType;
import java.lang.invoke.MethodHandles.Lookup;
import java.nio.ByteBuffer;
import java.nio.file.Files;
import java.nio.file.Paths;


import org.mozilla.classfile.ClassFileWriter;

import static org.mozilla.classfile.ByteCode.*;

/*
public class Main {
  public static void main(String[] args) {
    System.out.println(java.util.Arrays.toString(  {'h', 'e', 'l', 'l', 'o'}  ));
  }
}
*/
public class Gen {
  private static final ClassFileWriter.MethodHandle BSM =
    new ClassFileWriter.MethodHandle(MH_INVOKESTATIC,
        RT.class.getName().replace('.', '/'),
        "bootstrap",
        MethodType.methodType(
            CallSite.class, Lookup.class, String.class, MethodType.class, String.class
            ).toMethodDescriptorString());

  @SuppressWarnings("restriction")
  public static void main(String[] args) throws IOException {
    ClassFileWriter cw = new ClassFileWriter("Main2", "java/lang/Object", null);

    cw.startMethod("main", "([Ljava/lang/String;)V",
        (short) (ClassFileWriter.ACC_PUBLIC | ClassFileWriter.ACC_STATIC));
    cw.add(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");

    ByteBuffer byteBuffer = ByteBuffer.allocate(10);
    byteBuffer.asCharBuffer().put("hello".toCharArray());
    BASE64Encoder base64Encoder = new BASE64Encoder();
    String base64 = base64Encoder.encode(byteBuffer);
    cw.addInvokeDynamic("const", "()[C", BSM, base64);

    cw.addInvoke(INVOKESTATIC, "java/util/Arrays", "toString", "([C)Ljava/lang/String;");
    cw.addInvoke(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V");
    cw.add(RETURN);
    cw.stopMethod((short)1);

    Files.write(Paths.get("Main2.class"), cw.toByteArray());
  }
}