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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.commons.configuration2.resolver;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.Map;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
/**
* The DefaultEntityResolver used by XML Configurations.
*
* @since 1.7
*/
public class DefaultEntityResolver implements EntityResolver, EntityRegistry {
/** Stores a map with the registered public IDs. */
private final Map registeredEntities = new HashMap<>();
/**
* Gets a map with the entity IDs that have been registered using the {@code registerEntityId()} method.
*
* @return a map with the registered entity IDs
*/
@Override
public Map getRegisteredEntities() {
return registeredEntities;
}
/**
*
* Registers the specified URL for the specified public identifier.
*
*
* This implementation maps {@code PUBLICID}'s to URLs (from which the resource will be loaded). A common use case for
* this method is to register local URLs (possibly computed at runtime by a class loader) for DTDs and Schemas. This
* allows the performance advantage of using a local version without having to ensure every {@code SYSTEM} URI on every
* processed XML document is local. This implementation provides only basic functionality. If more sophisticated
* features are required, either calling {@code XMLConfiguration.setDocumentBuilder(DocumentBuilder)} to set a custom
* {@code DocumentBuilder} (which also can be initialized with a custom {@code EntityResolver}) or creating a custom
* entity resolver and registering it with the XMLConfiguration is recommended.
*
*
* @param publicId Public identifier of the Entity to be resolved
* @param entityURL The URL to use for reading this Entity
* @throws IllegalArgumentException if the public ID is undefined
*/
@Override
public void registerEntityId(final String publicId, final URL entityURL) {
if (publicId == null) {
throw new IllegalArgumentException("Public ID must not be null!");
}
getRegisteredEntities().put(publicId, entityURL);
}
/**
* Resolves the requested external entity. This is the default implementation of the {@code EntityResolver} interface.
* It checks the passed in public ID against the registered entity IDs and uses a local URL if possible.
*
* @param publicId the public identifier of the entity being referenced
* @param systemId the system identifier of the entity being referenced
* @return an input source for the specified entity
* @throws org.xml.sax.SAXException if a parsing exception occurs
*/
@SuppressWarnings("resource") // The stream is managed by the InputSource returned by this method.
@Override
public InputSource resolveEntity(final String publicId, final String systemId) throws SAXException {
// Has this system identifier been registered?
URL entityURL = null;
if (publicId != null) {
entityURL = getRegisteredEntities().get(publicId);
}
if (entityURL != null) {
// Obtain an InputSource for this URL. This code is based on the
// createInputSourceFromURL() method of Commons Digester.
try {
final URLConnection connection = entityURL.openConnection();
connection.setUseCaches(false);
final InputStream stream = connection.getInputStream();
final InputSource source = new InputSource(stream);
source.setSystemId(entityURL.toExternalForm());
return source;
} catch (final IOException e) {
throw new SAXException(e);
}
}
// default processing behavior
return null;
}
}