russell@unturf.com
0a580b313d
Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com Patches, unit tests, benchmarks, whitepaper, and outreach briefs. Public domain — no copyright claimed. Use freely.
101 lines
3.9 KiB
Java
101 lines
3.9 KiB
Java
/*
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* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package test;
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import java.lang.invoke.MethodHandle;
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import java.lang.invoke.MethodHandles;
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import java.lang.invoke.MethodHandles.Lookup;
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import java.lang.invoke.MethodType;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.util.Comparator;
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/*
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* java.util.Comparator is in java.base. MyComparator is a Comparator
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* subclass and it's in a different module.
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*
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* Test findSpecial and unreflectSpecial with Comparator and MyComparator
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* as the special caller.
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*/
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public class FindSpecial {
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private static final Lookup LOOKUP = MethodHandles.lookup();
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public static void main(String... args) throws Throwable {
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findSpecialTest();
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unreflectSpecialTest();
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reflectMethodInvoke();
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}
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static void findSpecialTest() throws Throwable {
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Method m = Comparator.class.getMethod("reversed");
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MethodType mt = MethodType.methodType(m.getReturnType(), m.getParameterTypes());
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// refc and specialCaller are both in java.base
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MethodHandle mh = LOOKUP.findSpecial(Comparator.class, m.getName(), mt, Comparator.class);
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// refc in java.base, specialCaller in this module
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MethodHandle mh1 = LOOKUP.findSpecial(m.getDeclaringClass(), m.getName(), mt,
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MyComparator.class);
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Comparator<Object> cmp = new MyComparator();
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// invokespecial to invoke Comparator::reversed.
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Object o = mh.invoke(cmp);
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Object o1 = mh1.invoke(cmp);
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}
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static void unreflectSpecialTest() throws Throwable {
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Method m = Comparator.class.getMethod("reversed");
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// refc and specialCaller are both in java.base
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MethodHandle mh = LOOKUP.unreflectSpecial(m, Comparator.class);
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// refc in java.base, specialCaller in this module
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MethodHandle mh1 = LOOKUP.unreflectSpecial(m, MyComparator.class);
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Comparator<Object> cmp = new MyComparator();
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// invokespecial to invoke Comparator::reversed.
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Object o = mh.invoke(cmp);
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Object o1 = mh1.invoke(cmp);
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}
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static void reflectMethodInvoke() throws Throwable {
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Method m = Comparator.class.getMethod("reversed");
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try {
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// invokevirtual dispatch
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Object o = m.invoke(new MyComparator());
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throw new RuntimeException("should throw an exception");
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} catch (InvocationTargetException e) {
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if (!(e.getCause() instanceof Error &&
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e.getCause().getMessage().equals("should not reach here"))) {
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throw e.getCause();
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}
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}
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}
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static class MyComparator implements Comparator<Object> {
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public int compare(Object o1, Object o2) {
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return 0;
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}
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@Override
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public Comparator<Object> reversed() {
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throw new Error("should not reach here");
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}
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}
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}
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