org.apache.jackrabbit.jcr2spi.xml.ImportHandler Maven / Gradle / Ivy
/*
* 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.jcr2spi.xml;
import javax.jcr.NamespaceException;
import javax.jcr.NamespaceRegistry;
import javax.jcr.RepositoryException;
import org.apache.jackrabbit.spi.Name;
import org.apache.jackrabbit.spi.NameFactory;
import org.apache.jackrabbit.spi.PathFactory;
import org.apache.jackrabbit.spi.commons.conversion.DefaultNamePathResolver;
import org.apache.jackrabbit.spi.commons.conversion.NamePathResolver;
import org.apache.jackrabbit.spi.commons.conversion.NameResolver;
import org.apache.jackrabbit.spi.commons.conversion.ParsingNameResolver;
import org.apache.jackrabbit.spi.commons.conversion.ParsingPathResolver;
import org.apache.jackrabbit.spi.commons.namespace.NamespaceResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.NamespaceSupport;
/**
* An ImportHandler instance can be used to import serialized
* data in System View XML or Document View XML. Processing of the XML is
* handled by specialized ContentHandlers
* (i.e. SysViewImportHandler and DocViewImportHandler).
*
* The actual task of importing though is delegated to the implementation of
* the {@link Importer} interface.
*
* Important Note:
*
* These SAX Event Handlers expect that Namespace URI's and local names are
* reported in the start/endElement events and that
* start/endPrefixMapping events are reported
* (i.e. default SAX2 Namespace processing).
*/
public class ImportHandler extends DefaultHandler {
private static Logger log = LoggerFactory.getLogger(ImportHandler.class);
private final Importer importer;
private final NamespaceRegistry nsReg;
private final NamespaceResolver nsResolver;
private final NameFactory nameFactory;
private ContentHandler targetHandler;
private boolean systemViewXML;
private boolean initialized;
private final NamespaceContext nsContext;
private final NamePathResolver resolver;
/**
* this flag is used to determine whether a namespace context needs to be
* started in the startElement event or if the namespace context has already
* been started in a preceding startPrefixMapping event;
* the flag is set per element in the first startPrefixMapping event and is
* cleared again in the following startElement event;
*/
protected boolean nsContextStarted;
public ImportHandler(Importer importer, NamespaceResolver nsResolver,
NamespaceRegistry nsReg, NameFactory nameFactory,
PathFactory pathFactory) {
this.importer = importer;
this.nsResolver = nsResolver;
this.nsReg = nsReg;
this.nameFactory = nameFactory;
nsContext = new NamespaceContext();
NameResolver nr = new ParsingNameResolver(nameFactory, nsContext);
resolver = new DefaultNamePathResolver(nr, new ParsingPathResolver(pathFactory, nr));
}
//---------------------------------------------------------< ErrorHandler >
/**
* {@inheritDoc}
*/
@Override
public void warning(SAXParseException e) throws SAXException {
// log exception and carry on...
log.warn("warning encountered at line: " + e.getLineNumber()
+ ", column: " + e.getColumnNumber()
+ " while parsing XML stream", e);
}
/**
* {@inheritDoc}
*/
@Override
public void error(SAXParseException e) throws SAXException {
// log exception and carry on...
log.error("error encountered at line: " + e.getLineNumber()
+ ", column: " + e.getColumnNumber()
+ " while parsing XML stream: " + e.toString());
}
/**
* {@inheritDoc}
*/
@Override
public void fatalError(SAXParseException e) throws SAXException {
// log and re-throw exception
log.error("fatal error encountered at line: " + e.getLineNumber()
+ ", column: " + e.getColumnNumber()
+ " while parsing XML stream: " + e.toString());
throw e;
}
//-------------------------------------------------------< ContentHandler >
/**
* {@inheritDoc}
*/
@Override
public void startDocument() throws SAXException {
systemViewXML = false;
initialized = false;
targetHandler = null;
/**
* start initial context containing existing mappings reflected
* by nsResolver
*/
nsContext.reset();
nsContext.pushContext();
try {
String[] uris = nsReg.getURIs();
for (int i = 0; i < uris.length; i++) {
nsContext.declarePrefix(nsResolver.getPrefix(uris[i]), uris[i]);
}
} catch (RepositoryException re) {
throw new SAXException(re);
}
// initialize flag
nsContextStarted = false;
}
/**
* {@inheritDoc}
*/
@Override
public void endDocument() throws SAXException {
// delegate to target handler
targetHandler.endDocument();
// cleanup
nsContext.reset();
}
/**
* {@inheritDoc}
*/
@Override
public void startPrefixMapping(String prefix, String uri)
throws SAXException {
// check if new context needs to be started
if (!nsContextStarted) {
// entering new namespace context
nsContext.pushContext();
nsContextStarted = true;
}
try {
// this will trigger NamespaceException if namespace is unknown
nsContext.getPrefix(uri);
} catch (NamespaceException nse) {
// namespace is not yet registered ...
try {
String newPrefix;
if ("".equals(prefix)) {
/**
* the xml document specifies a default namespace
* (i.e. an empty prefix); we need to create a random
* prefix as the empty prefix is reserved according
* to the JCR spec.
*/
newPrefix = getUniquePrefix(uri);
} else {
newPrefix = prefix;
}
// register new namespace
nsReg.registerNamespace(newPrefix, uri);
} catch (RepositoryException re) {
throw new SAXException(re);
}
}
// map namespace in this context to given prefix
nsContext.declarePrefix(prefix, uri);
}
/**
* {@inheritDoc}
*/
@Override
public void endPrefixMapping(String prefix) throws SAXException {
/**
* nothing to do here as namespace context has already been popped
* in endElement event
*/
}
/**
* {@inheritDoc}
*/
@Override
public void startElement(String namespaceURI, String localName, String qName,
Attributes atts) throws SAXException {
// check if new context needs to be started
if (!nsContextStarted) {
// there hasn't been a proceeding startPrefixMapping event
// so enter new namespace context
nsContext.pushContext();
} else {
// reset flag
nsContextStarted = false;
}
if (!initialized) {
// the namespace of the first element determines the type of XML
// (system view/document view)
systemViewXML = Name.NS_SV_URI.equals(namespaceURI);
if (systemViewXML) {
targetHandler = new SysViewImportHandler(importer, resolver);
} else {
targetHandler = new DocViewImportHandler(importer, resolver, nameFactory);
}
targetHandler.startDocument();
initialized = true;
}
// delegate to target handler
targetHandler.startElement(namespaceURI, localName, qName, atts);
}
/**
* {@inheritDoc}
*/
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
// delegate to target handler
targetHandler.characters(ch, start, length);
}
/**
* {@inheritDoc}
*/
@Override
public void endElement(String namespaceURI, String localName, String qName)
throws SAXException {
// leaving element, pop namespace context
nsContext.popContext();
// delegate to target handler
targetHandler.endElement(namespaceURI, localName, qName);
}
//--------------------------------------------------------< inner classes >
/**
* NamespaceContext supports scoped namespace declarations.
*/
class NamespaceContext implements NamespaceResolver {
private final NamespaceSupport nsContext;
/**
* NamespaceSupport doesn't accept "" as default uri;
* internally we're using " " instead
*/
private static final String DUMMY_DEFAULT_URI = " ";
NamespaceContext() {
nsContext = new NamespaceSupport();
}
void popContext() {
nsContext.popContext();
}
void pushContext() {
nsContext.pushContext();
}
void reset() {
nsContext.reset();
}
boolean declarePrefix(String prefix, String uri) {
if (Name.NS_DEFAULT_URI.equals(uri)) {
uri = DUMMY_DEFAULT_URI;
}
return nsContext.declarePrefix(prefix, uri);
}
//------------------------------------------------< NamespaceResolver >
/**
* {@inheritDoc}
*/
public String getURI(String prefix) throws NamespaceException {
String uri = nsContext.getURI(prefix);
if (uri == null) {
throw new NamespaceException("unknown prefix");
} else if (DUMMY_DEFAULT_URI.equals(uri)) {
return Name.NS_DEFAULT_URI;
} else {
return uri;
}
}
/**
* {@inheritDoc}
*/
public String getPrefix(String uri) throws NamespaceException {
if (Name.NS_DEFAULT_URI.equals(uri)) {
uri = DUMMY_DEFAULT_URI;
}
String prefix = nsContext.getPrefix(uri);
if (prefix == null) {
/**
* NamespaceSupport#getPrefix will never return the empty
* (default) prefix; we have to do a reverse-lookup to check
* whether it's the current default namespace
*/
if (uri.equals(nsContext.getURI(Name.NS_EMPTY_PREFIX))) {
return Name.NS_EMPTY_PREFIX;
}
throw new NamespaceException("unknown uri");
}
return prefix;
}
}
/**
* Returns a prefix that is unique among the already registered prefixes.
*
* @param uriHint namespace uri that serves as hint for the prefix generation
* @return a unique prefix
*/
public String getUniquePrefix(String uriHint) throws RepositoryException {
// TODO: smarter unique prefix generation
return "_pre" + (nsReg.getPrefixes().length + 1);
}
}