8161230: ClassLoader: add resource methods returning java.util.stream.Stream

Reviewed-by: psandoz, alanb, mchung, tvaleev
This commit is contained in:
Patrick Reinhart 2016-09-09 14:54:41 -07:00 committed by Paul Sandoz
parent a7dd7b59da
commit 5deb28b6a1
2 changed files with 146 additions and 0 deletions
jdk
src/java.base/share/classes/java/lang
test/java/lang/ClassLoader

@ -27,6 +27,7 @@ package java.lang;
import java.io.InputStream;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.io.File;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
@ -46,12 +47,16 @@ import java.util.Hashtable;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.Stack;
import java.util.NoSuchElementException;
import java.util.Vector;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import jdk.internal.perf.PerfCounter;
import jdk.internal.module.ServicesCatalog;
@ -1343,6 +1348,57 @@ public abstract class ClassLoader {
return new CompoundEnumeration<>(tmp);
}
/**
* Returns a stream whose elements are the URLs of all the resources with
* the given name. A resource is some data (images, audio, text, etc) that
* can be accessed by class code in a way that is independent of the
* location of the code.
*
* Resources in a named module are private to that module. This method does
* not find resources in named modules.
*
* <p> The name of a resource is a {@code /}-separated path name that
* identifies the resource.
*
* <p> The search order is described in the documentation for {@link
* #getResource(String)}.
*
* <p> The resources will be located when the returned stream is evaluated.
* If the evaluation results in an {@code IOException} then the I/O
* exception is wrapped in an {@link UncheckedIOException} that is then
* thrown.
*
* @apiNote When overriding this method it is recommended that an
* implementation ensures that any delegation is consistent with the {@link
* #getResource(java.lang.String) getResource(String)} method. This should
* ensure that the first element returned by the stream is the same
* resource that the {@code getResource(String)} method would return.
*
* @param name
* The resource name
*
* @return A stream of resource {@link java.net.URL URL} objects. If no
* resources could be found, the stream will be empty. Resources
* that the class loader doesn't have access to will not be in the
* stream.
*
* @see #findResources(String)
*
* @since 9
*/
public Stream<URL> resources(String name) {
int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE;
Supplier<Spliterator<URL>> si = () -> {
try {
return Spliterators.spliteratorUnknownSize(
getResources(name).asIterator(), characteristics);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
};
return StreamSupport.stream(si, characteristics, false);
}
/**
* Finds the resource with the given name. Class loader implementations
* should override this method to specify where to find resources.

@ -0,0 +1,90 @@
/*
* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import java.io.IOException;
import java.io.UncheckedIOException;
import java.net.URL;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/*
* @test
* @bug 8161230
* @summary Test java.lang.ClassLoader.resources() method
*
* @build ResourcesStreamTest
* @run main ResourcesStreamTest
*/
public class ResourcesStreamTest {
public static void main(String[] args) throws Exception {
testSuccess();
testFailure();
}
public static void testSuccess() throws Exception {
// failing part first
try {
ClassLoader cl = new FailingClassLoader();
// should create the stream pipe
Stream<URL> stream = cl.resources("the name");
// expect function to throw an exception when calling the method
stream.forEach(System.out::println);
throw new Exception("expected UncheckedIOException not thrown");
} catch (UncheckedIOException uio) {
String causeMessage = uio.getCause().getMessage();
if (!"the name".equals(causeMessage))
throw new Exception("unexpected cause message: " + causeMessage);
}
}
public static void testFailure() throws Exception {
ClassLoader cl = new SuccessClassLoader();
long count = cl.resources("the name").count();
if (count != 1)
throw new Exception("expected resource is null or empty");
cl.resources("the name")
.filter(url -> "file:/somefile".equals(url.toExternalForm()))
.findFirst()
.orElseThrow(() -> new Exception("correct URL not found"));
}
public static class SuccessClassLoader extends ClassLoader {
@Override
public Enumeration<URL> getResources(String name) throws IOException {
URL url = new URL("file:/somefile");
return Collections.enumeration(Collections.singleton(url));
}
}
public static class FailingClassLoader extends ClassLoader {
@Override
public Enumeration<URL> getResources(String name) throws IOException {
throw new IOException(name);
}
}
}