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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.
The newest version!
/*
* 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;
import org.apache.commons.discovery.Resource;
import org.apache.commons.discovery.ResourceDiscover;
import org.apache.commons.discovery.ResourceIterator;
import org.apache.commons.discovery.ResourceNameIterator;
import org.apache.commons.discovery.resource.names.ResourceNameDiscoverImpl;
/*
* Helper class for methods implementing the ResourceDiscover interface.
*/
public abstract class ResourceDiscoverImpl extends ResourceNameDiscoverImpl implements ResourceDiscover {
private ClassLoaders classLoaders;
/*
* Construct a new resource discoverer.
*/
public ResourceDiscoverImpl() {
}
/*
* Construct a new resource discoverer.
*
* @param classLoaders The class laoders holder
*/
public ResourceDiscoverImpl(ClassLoaders classLoaders) {
setClassLoaders(classLoaders);
}
/*
* Specify set of class loaders to be used in searching.
*
* @param loaders The class laoders holder
*/
public void setClassLoaders(ClassLoaders loaders) {
classLoaders = loaders;
}
/*
* Specify a new class loader to be used in searching.
*
* The order of loaders determines the order of the result.
* It is recommended to add the most specific loaders first.
*
* @param loader The new class loader to be added
*/
public void addClassLoader(ClassLoader loader) {
getClassLoaders().put(loader);
}
/*
* Returns the class loaders holder.
*
* @return The class loaders holder
*/
protected ClassLoaders getClassLoaders() {
if (classLoaders == null) {
classLoaders = ClassLoaders.getLibLoaders(this.getClass(), null, true);
}
return classLoaders;
}
/*
* {@inheritDoc}
*/
@Override
public ResourceNameIterator findResourceNames(String resourceName) {
return findResources(resourceName);
}
/*
* {@inheritDoc}
*/
@Override
public ResourceNameIterator findResourceNames(ResourceNameIterator resourceNames) {
return findResources(resourceNames);
}
/*
* Locate resources that are bound to {@code resourceName}.
*
* @param resourceName The resource name has to be located
* @return The located resources iterator
*/
public abstract ResourceIterator findResources(String resourceName);
/*
* Locate resources that are bound to resourceNames
.
*
* @param inputNames The resources name iterator has to be located
* @return The located resources iterator
*/
public ResourceIterator findResources(final ResourceNameIterator inputNames) {
return new ResourceIterator() {
private ResourceIterator resources = null;
private Resource resource = null;
public boolean hasNext() {
if (resource == null) {
resource = getNextResource();
}
return resource != null;
}
@Override
public Resource nextResource() {
Resource rsrc = resource;
resource = null;
return rsrc;
}
private Resource getNextResource() {
while (inputNames.hasNext() &&
(resources == null || !resources.hasNext())) {
resources = findResources(inputNames.nextResourceName());
}
return (resources != null && resources.hasNext())
? resources.nextResource()
: null;
}
};
}
}