ASM access invokedynamic bootstrap method information

AsmInvokeDynamic.java

import java.io.FileInputStream;
import static java.util.Arrays.asList;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.InvokeDynamicInsnNode;
import org.objectweb.asm.tree.MethodNode;

public class AsmInvokeDynamic {

    public static void main(String[] args) throws Exception {
        
        try (FileInputStream fis = new FileInputStream("C:\\Users\\User\\eclipse-workspace\\test\\bin\\Test.class")) {
            ClassReader classReader = new ClassReader(fis);
            ClassNode classNode = new ClassNode();
            
            classReader.accept(classNode, 0);
            
            MethodNode methodNode = classNode.methods.stream()
                    .filter(x -> x.name.equals("val"))
                    .findAny().get();
            
            AbstractInsnNode abstractInsnNode = methodNode.instructions.getFirst();
            while (abstractInsnNode != null) {
                if (abstractInsnNode instanceof InvokeDynamicInsnNode) {
                    InvokeDynamicInsnNode invokeDynamicInsnNode = (InvokeDynamicInsnNode) abstractInsnNode;
                    System.out.println(invokeDynamicInsnNode.name + " " + invokeDynamicInsnNode.desc);
                    System.out.println("bsmowner:" + invokeDynamicInsnNode.bsm.getOwner());
                    System.out.println("bsmname:" + invokeDynamicInsnNode.bsm.getName());
                    System.out.println("bsmdesc:" + invokeDynamicInsnNode.bsm.getDesc());
                    System.out.println(asList(invokeDynamicInsnNode.bsmArgs));
                    //
                    // Here's an example output...
                    //
                    // accept (Ljava/util/HashSet;)Ljava/util/function/Consumer;
                    // bsmowner:java/lang/invoke/LambdaMetafactory
                    // bsmname:metafactory
                    // bsmdesc:(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;
                    // [(Ljava/lang/Object;)V, java/util/HashSet.add(Ljava/lang/Object;)Z (5), (Ljava/lang/Integer;)V]
                    //
                    // Notice how the bootstrap method descriptor takes in 6 arguments but the bootstrap method arguments only supply 3.
                    // This is because the JVM implicitly supplies the first 3 arguments, then we supply the next 3. The following was
                    // lifted from https://github.com/Sable/soot/wiki/Java's-Invokedynamic...
                    //
                    //   The bootstrap method receives from the virtual machine three implicit arguments, in addition to the explicit
                    //   static arguments provided. A standard bootstrap method would start with the following argument signatures:
                    //
                    //   java.lang.invoke.MethodHandles$Lookup A lookup object representing the current class context.
                    //   java.lang.String                      The uninterpreted Utf8 string stated at the invokedynamic site.
                    //   java.lang.invoke.MethodType           A method type object representing the resolved method type for this
                    //                                       invokedynamic site.
                }
                
                abstractInsnNode = abstractInsnNode.getNext();
            }
        }
    }
}