/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed 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.springframework.beans.factory.xml;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
/**
* EntityResolver implementation that tries to resolve entity references
* through a {@link org.springframework.core.io.ResourceLoader} (usually,
* relative to the resource base of an ApplicationContext), if applicable.
* Extends {@link DelegatingEntityResolver} to also provide DTD and XSD lookup.
*
* <p>Allows to use standard XML entities to include XML snippets into an
* application context definition, for example to split a large XML file
* into various modules. The include paths can be relative to the
* application context's resource base as usual, instead of relative
* to the JVM working directory (the XML parser's default).
*
* <p>Note: In addition to relative paths, every URL that specifies a
* file in the current system root, i.e. the JVM working directory,
* will be interpreted relative to the application context too.
*
* @author Juergen Hoeller
* @since 31.07.2003
* @see org.springframework.core.io.ResourceLoader
* @see org.springframework.context.ApplicationContext
*/
public class ResourceEntityResolver extends DelegatingEntityResolver {
private static final Log logger = LogFactory.getLog(ResourceEntityResolver.class);
private final ResourceLoader resourceLoader;
/**
* Create a ResourceEntityResolver for the specified ResourceLoader
* (usually, an ApplicationContext).
* @param resourceLoader the ResourceLoader (or ApplicationContext)
* to load XML entity includes with
*/
public ResourceEntityResolver(ResourceLoader resourceLoader) {
super(resourceLoader.getClassLoader());
this.resourceLoader = resourceLoader;
}
@Override
public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
InputSource source = super.resolveEntity(publicId, systemId);
if (source == null && systemId != null) {
String resourcePath = null;
try {
String decodedSystemId = URLDecoder.decode(systemId);
String givenUrl = new URL(decodedSystemId).toString();
String systemRootUrl = new File("").toURL().toString();
// Try relative to resource base if currently in system root.
if (givenUrl.startsWith(systemRootUrl)) {
resourcePath = givenUrl.substring(systemRootUrl.length());
}
}
catch (Exception ex) {
// Typically a MalformedURLException or AccessControlException.
if (logger.isDebugEnabled()) {
logger.debug("Could not resolve XML entity [" + systemId + "] against system root URL", ex);
}
// No URL (or no resolvable URL) -> try relative to resource base.
resourcePath = systemId;
}
if (resourcePath != null) {
if (logger.isTraceEnabled()) {
logger.trace("Trying to locate XML entity [" + systemId + "] as resource [" + resourcePath + "]");
}
Resource resource = this.resourceLoader.getResource(resourcePath);
source = new InputSource(resource.getInputStream());
source.setPublicId(publicId);
source.setSystemId(systemId);
if (logger.isDebugEnabled()) {
logger.debug("Found XML entity [" + systemId + "]: " + resource);
}
}
}
return source;
}
}
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