org.exolab.castor.xml.util.resolvers.ByCDR Maven / Gradle / Ivy
/*
* Copyright 2007 Joachim Grueneis
*
* 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.exolab.castor.xml.util.resolvers;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.exolab.castor.mapping.ClassDescriptor;
import org.exolab.castor.xml.ResolverException;
import org.exolab.castor.xml.XMLConstants;
/**
* Resolves a class by reading the package level class-descriptor-resolver file and loading all
* descriptors mentioned inside.
*
* @author Joachim Grueneis
* @author Steven Dolg
* @version $Revision$ $Date$
* @since 1.2
*/
public class ByCDR extends AbstractResolverPackageCommand {
private static final Log LOG = LogFactory.getLog(ByCDR.class);
private List _loadedPackages = new ArrayList();
/**
* No specific stuff needed.
*/
public ByCDR() {
super();
}
/**
* Creates a Properties object and initializes it with the contents of the given URL. The provided
* URL must exist and be suitable for loading properties from.
*
* @param url The URL to load the properties from. This must not be null!
* @return The loaded properties.
* @throws IOException If loading the properties from the given ULR failed.
*
* @see Properties
* @see Properties#load(InputStream)
*/
private Properties getProperties(URL url) throws java.io.IOException {
Properties cdrList = new Properties();
java.io.InputStream stream = url.openStream();
cdrList.load(stream);
stream.close();
return cdrList;
}
/**
* Tries to load the CDR file for the given package name using the provided class loader. If the
* CDR file is available and could be loaded properly the descriptors listed in it are added to
* this cache.
* If a descriptor is listed in the CDR file for the given package but could not be loaded (e.g.
* because the reference class file is not available) the descriptor is ignored but no exception
* is thrown.
* If a CDR file is not available for the given package this method will not load any descriptors
* and not throw any exceptions.
* Further calls to this method with the same package name will not be processed.
* {@inheritDoc}
*/
protected Map internalResolve(final String packageName,
final ClassLoader classLoader, final Map properties) throws ResolverException {
Map results = new HashMap();
if (!isEmptyPackageName(packageName) && _loadedPackages.contains(packageName)) {
if (LOG.isDebugEnabled()) {
LOG.debug("Package: " + packageName + " has already been loaded.");
}
return results;
}
if (!isEmptyPackageName(packageName)) {
_loadedPackages.add(packageName);
}
URL url = classLoader.getResource(
ResolveHelpers.getQualifiedFileName(XMLConstants.PKG_CDR_LIST_FILE, packageName));
if (url == null) {
return results;
}
try {
Properties cdrList = this.getProperties(url);
for (Object clazz : cdrList.keySet()) {
String clazzName = (String) clazz;
String descriptorClassName = (String) cdrList.get(clazzName);
try {
Class descriptorClass = classLoader.loadClass(descriptorClassName);
if (LOG.isDebugEnabled()) {
LOG.debug("Found descriptor: " + descriptorClass);
}
if (descriptorClass != null) {
ClassDescriptor instance = (ClassDescriptor) descriptorClass.newInstance();
results.put(clazzName, instance);
} else if (LOG.isDebugEnabled()) {
LOG.debug("Loading of descriptor class: " + descriptorClassName + " for class: "
+ clazzName + " has failed - continue without");
}
} catch (Exception e) {
if (LOG.isDebugEnabled()) {
LOG.debug(
"Ignored problem at loading of: " + descriptorClassName + " with exception: " + e);
}
}
}
} catch (IOException iox) {
String message = "Failed to load package: " + packageName + " with exception: " + iox;
LOG.warn(message);
throw new ResolverException(message);
}
return results;
}
}