8161230: ClassLoader: add resource methods returning java.util.stream.Stream
Reviewed-by: psandoz, alanb, mchung, tvaleev
This commit is contained in:
parent
a7dd7b59da
commit
5deb28b6a1
jdk
src/java.base/share/classes/java/lang
test/java/lang/ClassLoader
@ -27,6 +27,7 @@ package java.lang;
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import java.io.InputStream;
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import java.io.IOException;
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import java.io.UncheckedIOException;
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import java.io.File;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.Field;
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@ -46,12 +47,16 @@ import java.util.Hashtable;
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import java.util.Map;
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import java.util.Objects;
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import java.util.Set;
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import java.util.Spliterator;
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import java.util.Spliterators;
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import java.util.Stack;
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import java.util.NoSuchElementException;
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import java.util.Vector;
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import java.util.WeakHashMap;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.function.Supplier;
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import java.util.stream.Stream;
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import java.util.stream.StreamSupport;
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import jdk.internal.perf.PerfCounter;
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import jdk.internal.module.ServicesCatalog;
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@ -1343,6 +1348,57 @@ public abstract class ClassLoader {
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return new CompoundEnumeration<>(tmp);
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}
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/**
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* Returns a stream whose elements are the URLs of all the resources with
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* the given name. A resource is some data (images, audio, text, etc) that
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* can be accessed by class code in a way that is independent of the
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* location of the code.
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*
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* Resources in a named module are private to that module. This method does
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* not find resources in named modules.
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*
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* <p> The name of a resource is a {@code /}-separated path name that
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* identifies the resource.
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*
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* <p> The search order is described in the documentation for {@link
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* #getResource(String)}.
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*
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* <p> The resources will be located when the returned stream is evaluated.
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* If the evaluation results in an {@code IOException} then the I/O
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* exception is wrapped in an {@link UncheckedIOException} that is then
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* thrown.
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*
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* @apiNote When overriding this method it is recommended that an
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* implementation ensures that any delegation is consistent with the {@link
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* #getResource(java.lang.String) getResource(String)} method. This should
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* ensure that the first element returned by the stream is the same
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* resource that the {@code getResource(String)} method would return.
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*
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* @param name
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* The resource name
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*
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* @return A stream of resource {@link java.net.URL URL} objects. If no
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* resources could be found, the stream will be empty. Resources
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* that the class loader doesn't have access to will not be in the
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* stream.
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*
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* @see #findResources(String)
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*
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* @since 9
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*/
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public Stream<URL> resources(String name) {
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int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
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Supplier<Spliterator<URL>> si = () -> {
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try {
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return Spliterators.spliteratorUnknownSize(
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getResources(name).asIterator(), characteristics);
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} catch (IOException e) {
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throw new UncheckedIOException(e);
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}
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};
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return StreamSupport.stream(si, characteristics, false);
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}
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/**
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* Finds the resource with the given name. Class loader implementations
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* should override this method to specify where to find resources.
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90
jdk/test/java/lang/ClassLoader/ResourcesStreamTest.java
Normal file
90
jdk/test/java/lang/ClassLoader/ResourcesStreamTest.java
Normal file
@ -0,0 +1,90 @@
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/*
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* Copyright (c) 2016, 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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import java.io.IOException;
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import java.io.UncheckedIOException;
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import java.net.URL;
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import java.util.Collections;
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import java.util.Enumeration;
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import java.util.List;
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import java.util.stream.Collectors;
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import java.util.stream.Stream;
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/*
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* @test
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* @bug 8161230
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* @summary Test java.lang.ClassLoader.resources() method
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*
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* @build ResourcesStreamTest
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* @run main ResourcesStreamTest
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*/
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public class ResourcesStreamTest {
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public static void main(String[] args) throws Exception {
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testSuccess();
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testFailure();
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}
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public static void testSuccess() throws Exception {
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// failing part first
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try {
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ClassLoader cl = new FailingClassLoader();
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// should create the stream pipe
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Stream<URL> stream = cl.resources("the name");
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// expect function to throw an exception when calling the method
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stream.forEach(System.out::println);
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throw new Exception("expected UncheckedIOException not thrown");
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} catch (UncheckedIOException uio) {
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String causeMessage = uio.getCause().getMessage();
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if (!"the name".equals(causeMessage))
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throw new Exception("unexpected cause message: " + causeMessage);
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}
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}
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public static void testFailure() throws Exception {
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ClassLoader cl = new SuccessClassLoader();
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long count = cl.resources("the name").count();
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if (count != 1)
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throw new Exception("expected resource is null or empty");
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cl.resources("the name")
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.filter(url -> "file:/somefile".equals(url.toExternalForm()))
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.findFirst()
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.orElseThrow(() -> new Exception("correct URL not found"));
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}
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public static class SuccessClassLoader extends ClassLoader {
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@Override
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public Enumeration<URL> getResources(String name) throws IOException {
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URL url = new URL("file:/somefile");
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return Collections.enumeration(Collections.singleton(url));
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}
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}
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public static class FailingClassLoader extends ClassLoader {
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@Override
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public Enumeration<URL> getResources(String name) throws IOException {
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throw new IOException(name);
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}
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}
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}
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