使用 ASM 将参数注解映射到 Class 文件中的方法参数

import org.objectweb.asm.*;

import java.io.IOException;
import java.lang.annotation.Deprecated;
import java.util.List;

public class ReadParameters extends ClassVisitor {
    public static void main(String[] args) throws IOException {
        for(Class<?> cl: List.of(Example.class, Example.Inner.class)) {
            System.out.println(cl);
            new ClassReader(cl.getName())
                .accept(new ReadParameters(), ClassReader.SKIP_CODE);
            System.out.println();
        }
    }

    @Override
    public MethodVisitor visitMethod(int access, String name, String descriptor,
                                     String signature, String[] exceptions) {
        System.out.println(" " + name);
        return new ParameterVisitor(name, descriptor);
    }

    static class ParameterVisitor extends MethodVisitor {
        final Type[] parameterTypes;
        int offset;

        ParameterVisitor(String name, String desc) {
            super(Opcodes.ASM9);
            parameterTypes = Type.getArgumentTypes(desc);
        }

        @Override
        public void visitAnnotableParameterCount(int parameterCount, boolean visible) {
            offset = parameterTypes.length - parameterCount;
            for(int i = 0; i < offset; i++)
                System.out.printf(" %3d %-20s %s%n",
                    i, parameterTypes[i].getClassName(), "(synthetic)");
        }

        @Override
        public AnnotationVisitor visitParameterAnnotation(
                int parameter, String descriptor, boolean visible) {
            parameter += offset;
            System.out.printf(" %3d %-20s %s%n", parameter,
                parameterTypes[parameter].getClassName(),
                Type.getType(descriptor).getClassName());
            return null;
        }
    }

    protected ReadParameters() {
        super(Opcodes.ASM9);
    }
}

// 示例类
enum Example {
    ;
    Example(@Deprecated int i) {}
    public class Inner {
        Inner(@Deprecated String foo) {}
    }
}