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SciJava Common is a shared library for SciJava software. It provides a plugin framework, with an extensible mechanism for service discovery, backed by its own annotation processor, so that plugins can be loaded dynamically. It is used by downstream projects in the SciJava ecosystem, such as ImageJ and SCIFIO.
/*
* #%L
* SciJava Common shared library for SciJava software.
* %%
* Copyright (C) 2009 - 2016 Board of Regents of the University of
* Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
* Institute of Molecular Cell Biology and Genetics.
* %%
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
* #L%
*/
package org.scijava.annotations;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
/**
* Makes the annotation indexes accessible.
*
* You would call it like this:
*
* for (IndexItem item : Index.load(MyAnnotation.class)) {
* // do something with item.annotation() and/or item.className()
* }
*
*
*
* @author Johannes Schindelin
*/
public class Index implements Iterable> {
/**
* Loads the index of all classes annotated with the specified annotation.
*
* The specified annotation needs to be annotated with {@link Indexable} for
* the annotation indexing to work properly, of course.
*
*
* @param annotation the annotation type
* @return the index
*/
public static Index load(final Class annotation)
{
return load(annotation, Thread.currentThread().getContextClassLoader());
}
/**
* Loads the index of all classes annotated with the specified annotation.
*
*
*
* @param annotation the annotation type
* @param loader the class loader to use when loading {@link Class}-type
* annotation fields
* @return the index
*/
public static Index load(final Class annotation,
final ClassLoader loader)
{
EclipseHelper.updateAnnotationIndex(loader);
return new Index<>(annotation, loader);
}
static final String INDEX_PREFIX = "META-INF/json/";
private static final String LEGACY_INDEX_PREFIX = "META-INF/annotations/";
private final Class annotation;
private final ClassLoader loader;
private Index(final Class annotation, final ClassLoader loader) {
this.annotation = annotation;
this.loader = loader;
}
private class IndexItemIterator implements Iterator> {
private Enumeration urls;
private IndexReader indexReader;
private IndexItem next;
private Set seen;
private Map legacyURLs;
public IndexItemIterator(final Class annotation) {
seen = new HashSet<>();
try {
legacyURLs = new LinkedHashMap<>();
final Enumeration legacy =
loader.getResources(LEGACY_INDEX_PREFIX + annotation.getName());
final int legacySuffixLength =
LEGACY_INDEX_PREFIX.length() + annotation.getName().length();
while (legacy.hasMoreElements()) {
final URL url = legacy.nextElement();
final String string = url.toString();
final String key =
string.substring(0, string.length() - legacySuffixLength) +
INDEX_PREFIX + annotation.getName();
legacyURLs.put(key, url);
}
if (legacyURLs.isEmpty()) {
legacyURLs = null;
}
urls = loader.getResources(INDEX_PREFIX + annotation.getName());
readNext();
}
catch (final IOException e) {
e.printStackTrace();
}
}
private void readNext() throws IOException {
for (;;) {
if (indexReader == null) {
try {
indexReader = getNextReader();
} catch (IOException e) {
e.printStackTrace();
continue;
}
if (indexReader == null) {
urls = null;
next = null;
return;
}
}
@SuppressWarnings("unchecked")
final Map map =
(Map) indexReader.next();
if (map != null) {
final String className = (String) map.get("class");
@SuppressWarnings("unchecked")
final Map values =
(Map) map.get("values");
next = new IndexItem<>(annotation, loader, className, values);
return;
}
indexReader.close();
indexReader = null;
}
}
private IndexReader getNextReader() throws IOException {
if (urls == null) {
return null;
}
while (urls.hasMoreElements()) {
final URL url = urls.nextElement();
if (seen.contains(url)) continue;
if (legacyURLs != null) {
legacyURLs.remove(url.toString());
}
seen.add(url);
return new IndexReader(url.openStream());
}
if (legacyURLs != null && !legacyURLs.isEmpty()) {
final Entry entry =
legacyURLs.entrySet().iterator().next();
legacyURLs.remove(entry.getKey());
return IndexReader.getLegacyReader(entry.getValue().openStream());
}
return null;
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public IndexItem next() {
final IndexItem result = next;
try {
readNext();
}
catch (final IOException e) {
e.printStackTrace();
next = null;
}
return result;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
}
@Override
public Iterator> iterator() {
return new IndexItemIterator(annotation);
}
}