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Its an port to fix bugs in OSGi support. ... The Apache Commons Discovery 0.5 component is about discovering, or finding,
implementations for pluggable interfaces.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.discovery.resource.names;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.discovery.ResourceNameDiscover;
import org.apache.commons.discovery.ResourceNameIterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Holder for multiple ResourceNameDiscover instances.
*
* The result is the union of the results from each
* (not a chained sequence, where results feed the next in line.
*/
public class NameDiscoverers extends ResourceNameDiscoverImpl implements ResourceNameDiscover {
private static Log log = LogFactory.getLog(NameDiscoverers.class);
/**
* Sets the {@code Log} for this class.
*
* @param _log This class {@code Log}
* @deprecated This method is not thread-safe
*/
@Deprecated
public static void setLog(Log _log) {
log = _log;
}
private final List discoverers = new ArrayList();
/**
* Construct a new resource name discoverer
*/
public NameDiscoverers() {
}
/**
* Specify an discover to be used in searching.
* The order of discover determines the order of the result.
* It is recommended to add the most specific discover first.
*
* @param discover The discover to be added
*/
public void addResourceNameDiscover(ResourceNameDiscover discover) {
if (discover != null) {
discoverers.add(discover);
}
}
/**
* Retrieve the discover positioned at the given index.
*
* @param idx The discover index position client is requiring
* @return The discover positioned at the input index
*/
protected ResourceNameDiscover getResourceNameDiscover(int idx) {
return discoverers.get(idx);
}
/**
* Returns the current size of set discovers.
*
* @return The current size of set discovers
*/
protected int size() {
return discoverers.size();
}
/**
* {@inheritDoc}
*/
@Override
public ResourceNameIterator findResourceNames(final String resourceName) {
if (log.isDebugEnabled()) {
log.debug("find: resourceName='" + resourceName + "'");
}
return new ResourceNameIterator() {
private int idx = 0;
private ResourceNameIterator iterator = null;
public boolean hasNext() {
if (iterator == null || !iterator.hasNext()) {
iterator = getNextIterator();
if (iterator == null) {
return false;
}
}
return iterator.hasNext();
}
public String nextResourceName() {
return iterator.nextResourceName();
}
private ResourceNameIterator getNextIterator() {
while (idx < size()) {
ResourceNameIterator iter =
getResourceNameDiscover(idx++).findResourceNames(resourceName);
if (iter.hasNext()) {
return iter;
}
}
return null;
}
};
}
}