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General purpose classes for use with the JCR API
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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.jackrabbit.commons;
import java.util.HashMap;
import java.util.Map;
import javax.jcr.NamespaceException;
import javax.jcr.NamespaceRegistry;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import org.apache.jackrabbit.util.XMLChar;
/**
* Helper class for working with JCR namespaces.
*
* @since Jackrabbit JCR Commons 1.5
*/
public class NamespaceHelper {
/**
* The jcr namespace URI.
*/
public static final String JCR = "http://www.jcp.org/jcr/1.0";
/**
* The nt namespace URI.
*/
public static final String NT = "http://www.jcp.org/jcr/nt/1.0";
/**
* The mix namespace URI.
*/
public static final String MIX = "http://www.jcp.org/jcr/mix/1.0";
/**
* Current session.
*/
private final Session session;
/**
* Creates a namespace helper for the given session.
*
* @param session current session
*/
public NamespaceHelper(Session session) {
this.session = session;
}
/**
* Returns a map containing all prefix to namespace URI mappings of
* the current session. The returned map is newly allocated and can
* can be freely modified by the caller.
*
* @see Session#getNamespacePrefixes()
* @return namespace mappings
* @throws RepositoryException if the namespaces could not be retrieved
*/
public Map getNamespaces() throws RepositoryException {
Map namespaces = new HashMap();
String[] prefixes = session.getNamespacePrefixes();
for (String prefixe : prefixes) {
namespaces.put(prefixe, session.getNamespaceURI(prefixe));
}
return namespaces;
}
/**
* Returns the prefix mapped to the given namespace URI in the current
* session, or null if the namespace does not exist.
*
* @see Session#getNamespacePrefix(String)
* @param uri namespace URI
* @return namespace prefix, or null
* @throws RepositoryException if the namespace could not be retrieved
*/
public String getPrefix(String uri) throws RepositoryException {
try {
return session.getNamespacePrefix(uri);
} catch (NamespaceException e) {
return null;
}
}
/**
* Returns the namespace URI mapped to the given prefix in the current
* session, or null if the namespace does not exist.
*
* @see Session#getNamespaceURI(String)
* @param prefix namespace prefix
* @return namespace prefix, or null
* @throws RepositoryException if the namespace could not be retrieved
*/
public String getURI(String prefix) throws RepositoryException {
try {
return session.getNamespaceURI(prefix);
} catch (NamespaceException e) {
return null;
}
}
/**
* Returns the prefixed JCR name for the given namespace URI and local
* name in the current session.
*
* @param uri namespace URI
* @param name local name
* @return prefixed JCR name
* @throws NamespaceException if the namespace does not exist
* @throws RepositoryException if the namespace could not be retrieved
*/
public String getJcrName(String uri, String name)
throws NamespaceException, RepositoryException {
if (uri != null && uri.length() > 0) {
return session.getNamespacePrefix(uri) + ":" + name;
} else {
return name;
}
}
/**
* Replaces the standard jcr, nt, or
* mix prefix in the given name with the prefix
* mapped to that namespace in the current session.
*
* The purpose of this method is to make it easier to write
* namespace-aware code that uses names in the standard JCR namespaces.
* For example:
*
* node.getProperty(helper.getName("jcr:data"));
*
*
* @param name prefixed name using the standard JCR prefixes
* @return prefixed name using the current session namespace mappings
* @throws IllegalArgumentException if the prefix is unknown
* @throws RepositoryException if the namespace could not be retrieved
*/
public String getJcrName(String name)
throws IllegalArgumentException, RepositoryException {
String standardPrefix;
String currentPrefix;
if (name.startsWith("jcr:")) {
standardPrefix = "jcr";
currentPrefix = session.getNamespacePrefix(JCR);
} else if (name.startsWith("nt:")) {
standardPrefix = "nt";
currentPrefix = session.getNamespacePrefix(NT);
} else if (name.startsWith("mix:")) {
standardPrefix = "mix";
currentPrefix = session.getNamespacePrefix(MIX);
} else {
throw new IllegalArgumentException("Unknown prefix: " + name);
}
if (currentPrefix.equals(standardPrefix)) {
return name;
} else {
return currentPrefix + name.substring(standardPrefix.length());
}
}
/**
* Safely registers the given namespace. If the namespace already exists,
* then the prefix mapped to the namespace in the current session is
* returned. Otherwise the namespace is registered to the namespace
* registry. If the given prefix is already registered for some other
* namespace or otherwise invalid, then another prefix is automatically
* generated. After the namespace has been registered, the prefix mapped
* to it in the current session is returned.
*
* @see NamespaceRegistry#registerNamespace(String, String)
* @param prefix namespace prefix
* @param uri namespace URI
* @return namespace prefix in the current session
* @throws RepositoryException if the namespace could not be registered
*/
public String registerNamespace(String prefix, String uri)
throws RepositoryException {
NamespaceRegistry registry =
session.getWorkspace().getNamespaceRegistry();
try {
// Check if the namespace is registered
registry.getPrefix(uri);
} catch (NamespaceException e1) {
// Replace troublesome prefix hints
if (prefix == null || prefix.length() == 0
|| prefix.toLowerCase().startsWith("xml")
|| !XMLChar.isValidNCName(prefix)) {
prefix = "ns"; // ns, ns2, ns3, ns4, ...
}
// Loop until an unused prefix is found
try {
String base = prefix;
for (int i = 2; true; i++) {
registry.getURI(prefix);
prefix = base + i;
}
} catch (NamespaceException e2) {
// Exit the loop
}
// Register the namespace
registry.registerNamespace(prefix, uri);
}
return session.getNamespacePrefix(uri);
}
/**
* Safely registers all namespaces in the given map from
* prefixes to namespace URIs.
*
* @param namespaces namespace mappings
* @throws RepositoryException if the namespaces could not be registered
*/
public void registerNamespaces(Map namespaces) throws RepositoryException {
for (Map.Entry stringStringEntry : namespaces.entrySet()) {
Map.Entry entry = stringStringEntry;
registerNamespace(entry.getKey(), entry.getValue());
}
}
}