Indy.java

package dyn;

import org.objectweb.asm.*;
import org.objectweb.asm.util.TraceClassVisitor;
import sun.dyn.anon.AnonymousClassLoader;

import java.io.PrintWriter;

public class Indy implements Opcodes {

   public static void main(String[] args) {
      MyCL myCL = new MyCL();
      Class caller = myCL.defineClass("Caller", makeCaller());
      try {
         caller.getMethod("foo").invoke(caller.newInstance());
      } catch (Exception e) {
         e.printStackTrace();
      }
   }

   public static class MyCL extends ClassLoader {
      public Class defineClass(String name, byte[] code) {
         return defineClass(name, code, 0, code.length);
      }
   }

   public static byte[] makeCaller() {
      ClassWriter cv = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
      TraceClassVisitor cw = new TraceClassVisitor(cv, new PrintWriter(System.out));

      MethodVisitor mv;

      cw.visit(51, ACC_PUBLIC+ACC_SUPER, "Caller", null, "dyn/Invoker", null);

      cw.visitField(ACC_PUBLIC, "callee", "Ljava/lang/Class;", null, null).visitEnd();

      {
         mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
         mv.visitCode();
         mv.visitVarInsn(ALOAD, 0);
         mv.visitMethodInsn(INVOKESPECIAL, "dyn/Invoker", "<init>", "()V");

         mv.visitVarInsn(ALOAD, 0);
         mv.visitTypeInsn(NEW, "sun/dyn/anon/AnonymousClassLoader");
         mv.visitInsn(DUP);
         mv.visitMethodInsn(INVOKESPECIAL, "sun/dyn/anon/AnonymousClassLoader", "<init>", "()V");
         mv.visitMethodInsn(INVOKESTATIC, "dyn/Indy", "makeCallee", "()[B");
         mv.visitMethodInsn(INVOKEVIRTUAL, "sun/dyn/anon/AnonymousClassLoader", "loadClass", "([B)Ljava/lang/Class;");
         mv.visitFieldInsn(PUTFIELD, "Caller", "callee", "Ljava/lang/Class;");

         mv.visitInsn(RETURN);
         mv.visitMaxs(0, 0);
         mv.visitEnd();
      }
      {
         mv = cw.visitMethod(ACC_PUBLIC, "foo", "()V", null, null);
         mv.visitCode();
         mv.visitVarInsn(ALOAD, 0);
         mv.visitInsn(DUP);

         mv.visitFieldInsn(GETFIELD, "Caller", "callee", "Ljava/lang/Class;");
         mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Class", "newInstance", "()Ljava/lang/Object;");
         mv.visitFieldInsn(PUTFIELD, "Caller", "targetObject", "Ljava/lang/Object;");

         mv.visitLdcInsn("cde");
         mv.visitInvokeDynamicInsn("my:stuff", "(Ljava/lang/String;)V",
               new MethodHandle(MH_INVOKEVIRTUAL, "Caller", "bootstrap",
               new MethodType(Invoker.class.getMethods()[0]).getDescriptor()));
         mv.visitInsn(RETURN);
         mv.visitMaxs(0, 0);
         mv.visitEnd();
      }
      cw.visitEnd();

      return cv.toByteArray();
   }

   public static byte[] makeCallee() {
      ClassWriter cv = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
      TraceClassVisitor cw = new TraceClassVisitor(cv, new PrintWriter(System.out));
      MethodVisitor mv;

      cw.visit(51, ACC_PUBLIC, "Callee", null, "java/lang/Object", null);

      {
         mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
         mv.visitCode();
         mv.visitVarInsn(ALOAD, 0);
         mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
         mv.visitInsn(RETURN);
         mv.visitMaxs(1, 1);
         mv.visitEnd();
      }
      {
         mv = cw.visitMethod(ACC_PUBLIC, "bar", "(Ljava/lang/String;)V", null, null);
         mv.visitCode();
         mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
         mv.visitTypeInsn(NEW, "java/lang/StringBuilder");
         mv.visitInsn(DUP);
         mv.visitMethodInsn(INVOKESPECIAL, "java/lang/StringBuilder", "<init>", "()V");
         mv.visitLdcInsn("in bar ");
         mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;");
         mv.visitVarInsn(ALOAD, 1);
         mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "append", "(Ljava/lang/String;)Ljava/lang/StringBuilder;");
         mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/StringBuilder", "toString", "()Ljava/lang/String;");
         mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V");
         mv.visitInsn(RETURN);
         mv.visitMaxs(0, 0);
         mv.visitEnd();
      }
      cw.visitEnd();

      return cv.toByteArray();
   }
}

Invoker.java

package dyn;

import java.dyn.*;

public class Invoker {

   protected Object targetObject;

   public CallSite bootstrap(MethodHandles.Lookup lookup, String name, MethodType type) {
      try {
         MethodHandle handle = lookup.bind(targetObject, "bar",
               MethodType.methodType(void.class, String.class));
         return new ConstantCallSite(handle);
      } catch (NoAccessException e) {
         throw new RuntimeException("Failed lookup", e);
      }
   }
}