Java高并发中AtomicIntegerFieldUpdater访问权限问题

final Field field;
final int modifiers;
try {
	field = AccessController.doPrivileged(
		new PrivilegedExceptionAction<Field>() {
			public Field run() throws NoSuchFieldException {
				return tclass.getDeclaredField(fieldName);
			}
		});
	modifiers = field.getModifiers();
	sun.reflect.misc.ReflectUtil.ensureMemberAccess(
		caller, tclass, null, modifiers);
	ClassLoader cl = tclass.getClassLoader();
	ClassLoader ccl = caller.getClassLoader();
	if ((ccl != null) && (ccl != cl) &&
		((cl == null) || !isAncestor(cl, ccl))) {
		sun.reflect.misc.ReflectUtil.checkPackageAccess(tclass);
	}
} catch (PrivilegedActionException pae) {
	throw new RuntimeException(pae.getException());
} catch (Exception ex) {
	throw new RuntimeException(ex);
}