Am 09.10.2014 19:07, schrieb Remi Forax:
public static void main(String[] args) throws NoSuchFieldException,
IllegalArgumentException, IllegalAccessException {
Lookup lookup = MethodHandles.publicLookup().in(Consumer.class);
Field allowedModes = Lookup.class.getDeclaredField("allowedModes");
allowedModes.setAccessible(true);
allowedModes.set(lookup, Modifier.PRIVATE);
@SuppressWarnings("unchecked")
Consumer<Object> consumer = (Consumer<Object>)Proxy.newProxyInstance(
CallingADefaultMethodInAProxy.class.getClassLoader(),
new Class<?>[]{Consumer.class},
(Object proxy, Method method, Object[] array) -> {
if (method.isDefault()) {
MethodHandle mh = lookup.unreflectSpecial(method,
Consumer.class);
return
mh.invokeWithArguments(Stream.concat(Stream.of(proxy),
Arrays.stream(array)).toArray());
}
System.out.println("hello");
return null;
});
consumer.andThen(System.out::println).accept("default method");
}
Not very pretty, if someone ask me I will deny to have written that code :)
lol.
The other variant is to get the Lookup constructor accepting an int, to
make private level access possible. But is that really supposed to be a
standard solution? I mean I could then use Unsafe too ;)
John, I've discovered that findSpecial/unreflectSpecial doesn't honor
setAccessible,
given that the whole point of unreflectSpecial is to see a virtual call
as a super call,
it looks like a bug to me.
yes, I found the same thing strange... though given the special nature
of invokespecial I was thinking that this limitation is there to ensure
this "call has to be done from same class or subclass" logic. So I would
expect for example, that if I do MethodHandles.lookup().in(Foo.class),
while being in Foo or a subclass that it would work. But of course, that
is of zero use if Foo is an interface and whole purpose of the exercise
is to have a proxy that acts as that interface instead of having to
implement the interface yourself. But I did not actually test if my
assumption is right.
bye Jochen
--
Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
blog: http://blackdragsview.blogspot.com/
german groovy discussion newsgroup: de.comp.lang.misc
For Groovy programming sources visit http://groovy-lang.org
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