Java ClassReader-class And Method Code Example

Here is another example of how you might use a ClassReader to read and print the methods of a Java class:

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

public class Example {
    public static void main(String[] args) throws Exception {
        // Read the class file as a byte array
        byte[] bytes = readClassFile();

        // Use the ClassReader to parse the bytecode
        ClassReader cr = new ClassReader(bytes);

        // Create a ClassVisitor that will be used to visit the methods of the class
        ClassVisitor cv = new ClassVisitor(Opcodes.ASM8) {
            public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
                // Print the method information
                System.out.println("Method: " + name + " " + desc);

                // Return a MethodVisitor that will be used to visit the bytecode of the method
                return new MethodVisitor(Opcodes.ASM8) {
                    // Override the visitInsn method to print the bytecode instructions
                    public void visitInsn(int opcode) {
                        System.out.println("  " + opcode);

        // Have the ClassReader accept the ClassVisitor, which will cause it to call the appropriate methods
        cr.accept(cv, ClassReader.SKIP_DEBUG);

In this example, the ClassReader is used to parse the bytecode of the class and the ClassVisitor is used to visit the methods of the class. The MethodVisitor is used to visit the bytecode of each method, and the visitInsn method is overridden to print the bytecode instructions. When the accept method is called on the ClassReader, it will call the appropriate methods on the ClassVisitor, which will in turn call the appropriate methods on the MethodVisitor.