/*
* 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.exoplatform.services.jcr.impl.core.query.lucene;
import org.exoplatform.commons.utils.PrivilegedFileHelper;
import org.exoplatform.services.log.ExoLogger;
import org.exoplatform.services.log.Log;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import javax.jcr.NamespaceException;
import javax.jcr.RepositoryException;
/**
* The class <code>NamespaceMappings</code> implements a
* NamespaceResolver that holds a namespace
* mapping that is used internally in the search index. Storing paths with the
* full uri of a namespace would require too much space in the search index.
* <br>
* Whenever a yet unknown namespace uri to prefix mapping is requested, a new
* prefix is created on the fly and associated with the namespace. Known
* namespace mappings are stored in a properties file.
*/
public class FileBasedNamespaceMappings extends AbstractNamespaceMappings
{
/**
* Default logger instance for this class
*/
private static Log log = ExoLogger.getLogger("exo.jcr.component.core.NamespaceMappings");
/**
* Location of the file that persists the uri / prefix mappings
*/
private final File storage;
/**
* Map of uris indexed by prefixes
*/
private Map<String, String> prefixToURI = new HashMap<String, String>();
/**
* Map of prefixes indexed by uris
*/
private Map<String, String> uriToPrefix = new HashMap<String, String>();
/**
* Current prefix count.
*/
private int prefixCount;
/**
* Creates <code>NamespaceMappings</code> instance. Initial mappings are
* loaded from <code>file</code>.
*
* @param file the <code>File</code> to load initial mappings.
* @throws IOException if an error occurs while reading initial namespace
* mappings from <code>file</code>.
*/
public FileBasedNamespaceMappings(File file) throws IOException
{
storage = file;
load();
}
/**
* Returns a namespace uri for a <code>prefix</code>.
*
* @param prefix the namespace prefix.
* @return the namespace uri.
* @throws NamespaceException if no namespace uri is registered for
* <code>prefix</code>.
*/
public synchronized String getNamespaceURIByPrefix(String prefix) throws NamespaceException
{
if (!prefixToURI.containsKey(prefix))
{
throw new NamespaceException(prefix + ": is not a registered namespace prefix.");
}
return prefixToURI.get(prefix);
}
/**
* Returns a prefix for the namespace <code>uri</code>. If a namespace
* mapping exists, the already known prefix is returned; otherwise a new
* prefix is created and assigned to the namespace uri.
*
* @param uri the namespace uri.
* @return the prefix for the namespace uri.
* @throws NamespaceException if an yet unknown namespace uri / prefix
* mapping could not be stored.
*/
public synchronized String getNamespacePrefixByURI(String uri) throws NamespaceException
{
String prefix = uriToPrefix.get(uri);
if (prefix == null)
{
// make sure prefix is not taken
while (prefixToURI.get(String.valueOf(prefixCount)) != null)
{
prefixCount++;
}
prefix = String.valueOf(prefixCount);
prefixToURI.put(prefix, uri);
uriToPrefix.put(uri, prefix);
log.debug("adding new namespace mapping: " + prefix + " -> " + uri);
try
{
store();
}
catch (IOException e)
{
throw new NamespaceException("Could not obtain a prefix for uri: " + uri, e);
}
}
return prefix;
}
//-----------------------< internal >---------------------------------------
/**
* Loads currently known mappings from a .properties file.
*
* @throws IOException if an error occurs while reading from the file.
*/
private void load() throws IOException
{
if (PrivilegedFileHelper.exists(storage))
{
InputStream in = PrivilegedFileHelper.fileInputStream(storage);
try
{
Properties props = new Properties();
log.debug("loading namespace mappings...");
props.load(in);
// read mappings from properties
Iterator<Object> iter = props.keySet().iterator();
while (iter.hasNext())
{
String prefix = (String)iter.next();
String uri = props.getProperty(prefix);
log.debug(prefix + " -> " + uri);
prefixToURI.put(prefix, uri);
uriToPrefix.put(uri, prefix);
}
prefixCount = props.size();
log.debug("namespace mappings loaded.");
}
finally
{
in.close();
}
}
}
/**
* Writes the currently known mappings into a .properties file.
*
* @throws IOException if an error occurs while writing the file.
*/
private void store() throws IOException
{
Properties props = new Properties();
// store mappings in properties
Iterator<String> iter = prefixToURI.keySet().iterator();
while (iter.hasNext())
{
String prefix = iter.next();
String uri = prefixToURI.get(prefix);
props.setProperty(prefix, uri);
}
OutputStream out = PrivilegedFileHelper.fileOutputStream(storage);
try
{
out = new BufferedOutputStream(out);
props.store(out, null);
}
finally
{
// make sure stream is closed
out.close();
}
}
public String[] getAllNamespacePrefixes() throws RepositoryException
{
return (String[])prefixToURI.keySet().toArray(new String[prefixToURI.keySet().size()]);
}
}