Hi everyone, I am glad this was discussed on the list again. I just wanted to throw out there, as a library developer and end user, I now have had to reproduce this hack in no fewer than four different projects for various reasons.
It is even worse because it means that my library cannot run under a SecurityManager. While this isn't a problem for me personally it does limit the utility of any libraries I might produce. It really is a glaring missing API and if it does not make Java 9 I can't imagine I will be the only person that is extremely disappointed. Thanks, Steven > On Jun 6, 2016, at 1:58 PM, Mandy Chung <mandy.ch...@oracle.com> wrote: > > Hi Peter, > > Thanks for the proposal. This feature has been lacking. When this subject > was brought, I also have similiar thought to provide a way in Proxy class for > InvocationHandler to invoke a default method (but of course no time to put > into it). > > I appreciate your contribution and good work. I support to add this feature > in a future release. > > I personally don’t feel comfortable to absorb this small API targetting for > JDK 9 (since I don’t have the cycle to shepherd this in the next few months). > I may be overly conversative but I won’t take security assessment lightly. > Maybe someone else is able to help you move this forward before I am > available. > > Mandy > >> On Jun 3, 2016, at 7:58 AM, Peter Levart <peter.lev...@gmail.com> wrote: >> >> Hi, >> >> Since Java SE 8 introduced default methods in interfaces there was a >> question what to do with java.lang.reflect.Proxy API. Nothing was done to >> the API at that time, so the default behavior is to proxy default methods >> too. InvocationHandler gets invoked for default methods, but it has not >> provision to forward such calls to the default implementations in the >> interfaces. >> >> I propose a simple API addition that allows calling super default methods in >> proxy instances: >> >> http://cr.openjdk.java.net/~plevart/jdk9-dev/Proxy.invokeSuperDefaults/webrev.02/ >> >> With this addition one can simply decide in the InvocationHandler what to do >> with invocations to default methods and can forward such invocation to the >> default implementation: >> >> public class Test { >> >> interface I1 { >> default void m() { >> System.out.println(" default I1.m() called"); >> } >> } >> >> interface I2 { >> default void m() { >> System.out.println(" default I2.m() called"); >> } >> } >> >> interface I12 extends I1, I2 { >> @Override >> void m(); >> >> default int sum(int a, int b) { >> return a + b; >> } >> >> default Object[] concat(Object first, Object... rest) { >> Object[] result = new Object[1 + rest.length]; >> result[0] = first; >> System.arraycopy(rest, 0, result, 1, rest.length); >> return result; >> } >> } >> >> public static void main(String[] args) { >> >> InvocationHandler h = (proxy, method, params) -> { >> System.out.println("\nInvocationHandler called for: " + method + >> " with parameters: " + Arrays.toString(params)); >> if (method.isDefault()) { >> try { >> return Proxy.invokeSuper(proxy, method, params); >> } catch (InvocationTargetException e) { >> throw e.getCause(); >> } >> } else { >> switch (method.getName()) { >> case "m": >> System.out.println(" abstract I12.m(): called"); >> return null; >> default: >> throw new UnsupportedOperationException( >> "Unsupported method: " + method); >> } >> } >> }; >> >> I1 i1 = (I1) Proxy.newProxyInstance( >> I1.class.getClassLoader(), new Class<?>[]{I1.class}, h); >> i1.m(); >> >> I2 i2 = (I2) Proxy.newProxyInstance( >> I2.class.getClassLoader(), new Class<?>[]{I2.class}, h); >> i2.m(); >> >> I12 i12 = (I12) Proxy.newProxyInstance( >> I12.class.getClassLoader(), new Class<?>[]{I12.class}, h); >> i12.m(); >> >> System.out.println(" 1 + 2 = " + i12.sum(1, 2)); >> System.out.println(" [1] concat [2, 3, 4] = " + >> Arrays.toString(i12.concat(1, 2, 3, 4))); >> } >> } >> >> >> I know FC date is over, but this is really a small change and I have heard >> several people that such feature is missing from the Proxy API. >> >> I'm prepared to create jtreg tests covering the specification if this >> proposal is accepted. >> >> Regards, Peter >> >> >> >
