How to resolve "InaccessibleObjectException" of jdk16-CodePudding

I met a problem when I work for the framework: https://github.com/babyfish-ct/kimmer/

After I published the first version. I run the example, an exception raised

java.lang.reflect.InaccessibleObjectException: Unable to make protected final java.lang.Class java.lang.ClassLoader.defineClass(byte[],int,int) throws java.lang.ClassFormatError accessible: module java.base does not "opens java.lang" to unnamed module @74ea2410

This framework uses ASM to generate bytecode directly. It doesn't matter, using the higher-level cglib framework will encounter the same problem.

The problem is my framework(or cglib) wants to define new classes by runtime generated bytecode on EXISTING ClassLoader. To do this, I need to access protection-level methods under java.lang.ClassLoader through reflection, get the PROTECTED method and change its visibility, like this

private val DEFINE_CLASS = ClassLoader::class.java.getDeclaredMethod(
    "defineClass",
    ByteArray::class.java,
    Int::class.javaPrimitiveType,
    Int::class.javaPrimitiveType,
).also {
    it.isAccessible = true
}

Actually, I learned this trick from cglib's source code 10 years ago，this trick has been helping me.

Now, The JDK has become strict and this behavior is prohibited. I had to go and read the source code of the latest version of cglib. In ReflectUtils.java, I found cglib is trying to use "defineClass" of "sun.misc.Unsafe". Unfortunately, I can find that class but cannot find that method in "OpenJDK Runtime Environment Zulu16.30 19-CA".

I feel this problem is caused by jigsaw but I'm not jigsaw expert, so I left it open and let the user use "--illegal-access=permit".

How to resolve this problem and let my problems can work perfectly on latest JVM?

CodePudding user response：

Here is the relevant issue in that library, it may be helpful to find hacks that allow it to work for yours. https://github.com/cglib/cglib/issues/191.

Its usually on the library itself to add support for Java Modules.

CodePudding user response：

Resolved.

This problem can be resolved by https://github.com/jboss-javassist/javassist/blob/master/src/main/javassist/util/proxy/DefineClassHelper.java perfectly, I will use some of its code to fix this problem on next version