利用ASM删除方法时，报java.lang.ClassFormatError

Question

如果将cv.visitMethod对象取出来会报错，然后发现class文件只移除了方法体，但是方法还在，但是我根本没有用到取出来的对象，想请问一下为什么会造成这样的影响？

代码如下：

public class AddSecurityCheckClassAdapter extends ClassAdapter {
    public AddSecurityCheckClassAdapter(ClassVisitor cv) {
        super(cv);
    }    
    @Override
    public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
        //加了这行会报错
        MethodVisitor mv = cv.visitMethod(access, name, desc, signature, exceptions);
        System.out.println("AddSecurityCheckClassAdapter;" + "name:" + name + ";desc:" + desc + ";signature:" + signature);
            if ("operation".equals(name)) {
                return null;
            }
        return cv.visitMethod(access, name, desc, signature, exceptions);
    }
}

错误信息如下：

Exception in thread "main" java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file Account
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:756)
	at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
	at java.net.URLClassLoader.defineClass(URLClassLoader.java:468)
	at java.net.URLClassLoader.access$100(URLClassLoader.java:74)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:369)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:363)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:362)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
	at Test.main(Test.java:28)

Process finished with exit code 1

Answer 1

看这个：https://blog.csdn.net/mbugatti/article/details/53410506