org.apache.wicket.application.CompoundClassResolver Maven / Gradle / Ivy
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/*
* 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.wicket.application;
import java.net.URL;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.CopyOnWriteArrayList;
import org.apache.wicket.util.collections.UrlExternalFormComparator;
import org.apache.wicket.util.lang.Args;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A thread safe compound {@link IClassResolver}. Class resolving is done by iterating through all
* {@link IClassResolver}s until the class is found. Resource resolving is done by combining the
* results of all {@link IClassResolver}s.
*
* @author Jesse Long
*/
public class CompoundClassResolver implements IClassResolver
{
private static final Logger logger = LoggerFactory.getLogger(CompoundClassResolver.class);
private final List resolvers = new CopyOnWriteArrayList();
/**
* {@inheritDoc}
*
* This implementation iterates through all the {@link IClassResolver} trying to load the class
* until the class is found.
*
* @param className
* The name of the class to resolve.
* @return The {@link Class}, if it is found.
* @throws ClassNotFoundException
* If the class was not found
*/
public Class resolveClass(final String className) throws ClassNotFoundException
{
boolean debugEnabled = logger.isDebugEnabled();
for (IClassResolver resolver : resolvers)
{
try
{
return resolver.resolveClass(className);
}
catch (ClassNotFoundException cnfx)
{
if (debugEnabled)
{
logger.debug("ClassResolver '{}' cannot find class: '{}'", resolver.getClass()
.getName(), className);
}
}
}
throw new ClassNotFoundException(className);
}
/**
* {@inheritDoc}
*
* This implementation iterates through all {@link IClassResolver}s added, and combines the
* results into one {@link Set} of {@link URL}s, and returns an {@link Iterator} for the set.
* {@link URL}s are unique in the set.
*
* @param name
* The name of the resource to find.
* @return An {@link Iterator} of all the {@link URL}s matching the resource name.
*/
public Iterator getResources(final String name)
{
Args.notNull(name, "name");
Set urls = new TreeSet(new UrlExternalFormComparator());
for (IClassResolver resolver : resolvers)
{
Iterator it = resolver.getResources(name);
while (it.hasNext())
{
URL url = it.next();
urls.add(url);
}
}
return urls.iterator();
}
/**
* Adds a resolver
*
* @param resolver
* The resolver to add
* @return {@code this} for chaining
*/
public CompoundClassResolver add(final IClassResolver resolver)
{
Args.notNull(resolver, "resolver");
resolvers.add(resolver);
return this;
}
/**
* Removes a resolver
*
* @param resolver
* The resolver to remove
* @return {@code this} for chaining
*/
public CompoundClassResolver remove(final IClassResolver resolver)
{
resolvers.remove(resolver);
return this;
}
}