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/*
* $Id: XMLStreamUtils.java,v 1.8 2004/07/09 17:30:50 cniles Exp $
*
* Copyright (c) 2004, Christian Niles, Unit12
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* * Neither the name of Christian Niles, Unit12, nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
package javanet.staxutils;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventFactory;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLEventWriter;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;
import javax.xml.stream.util.XMLEventConsumer;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
/**
* Static utility methods useful when handling XML Streams.
*
* @author Christian Niles
* @version $Revision: 1.8 $
*/
public class XMLStreamUtils {
private static XMLInputFactory inputFactory = XMLInputFactory.newInstance();
private static XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
private static final String[] EVENT_NAMES = new String[16];
static {
EVENT_NAMES[0] = ""; // no event has 0 index
EVENT_NAMES[XMLStreamConstants.ATTRIBUTE] = "ATTRIBUTE";
EVENT_NAMES[XMLStreamConstants.CDATA] = "CDATA";
EVENT_NAMES[XMLStreamConstants.CHARACTERS] = "CHARACTERS";
EVENT_NAMES[XMLStreamConstants.COMMENT] = "COMMENT";
EVENT_NAMES[XMLStreamConstants.DTD] = "DTD";
EVENT_NAMES[XMLStreamConstants.END_DOCUMENT] = "END_DOCUMENT";
EVENT_NAMES[XMLStreamConstants.END_ELEMENT] = "END_ELEMENT";
EVENT_NAMES[XMLStreamConstants.ENTITY_DECLARATION] = "ENTITY_DECLARATION";
EVENT_NAMES[XMLStreamConstants.ENTITY_REFERENCE] = "ENTITY_REFERENCE";
EVENT_NAMES[XMLStreamConstants.NAMESPACE] = "NAMESPACE";
EVENT_NAMES[XMLStreamConstants.NOTATION_DECLARATION] = "NOTATION_DECLARATION";
EVENT_NAMES[XMLStreamConstants.PROCESSING_INSTRUCTION] = "PROCESSING_INSTRUCTION";
EVENT_NAMES[XMLStreamConstants.SPACE] = "SPACE";
EVENT_NAMES[XMLStreamConstants.START_DOCUMENT] = "START_DOCUMENT";
EVENT_NAMES[XMLStreamConstants.START_ELEMENT] = "START_ELEMENT";
}
/**
* Returns the name of the specified stream event constant.
*
* @param eventType
* The event constant, such as
* {@link XMLStreamConstants#START_DOCUMENT}.
* @return The name of the specified event, or "UNKNOWN" if the
* constant isn't valid.
*/
public static final String getEventTypeName(int eventType) {
if (eventType > 0 || eventType < EVENT_NAMES.length) {
return EVENT_NAMES[eventType];
} else {
return "UNKNOWN";
}
}
/**
* Returns the value of the attribute with the given non-qualified name.
*
* @param reader
* The xml stream reader
* @param name
* The name of the attribute.
* @return The value of the unqualified attribute, or null if the
* attribute wasn't present.
*/
public static final String attributeValue(XMLStreamReader reader, String name) {
return reader.getAttributeValue("", name);
}
/**
* Returns the value of the attribute with the given name.
*
* @param reader
* The xml stream reader
* @param name
* The name of the attribute.
* @return The value of the attribute, or null if the attribute
* wasn't present.
*/
public static final String attributeValue(XMLStreamReader reader, QName name) {
return reader.getAttributeValue(name.getNamespaceURI(), name.getLocalPart());
}
/**
* Skips all events within a single element, including its start and end tags.
* The provided reader must be positioned directly in front of a
* StartElement event or it will have no effect. After this
* method completes, the reader will be positioned before the event following
* the end tag (the end tag will have been read).
*
* @param reader
* The event stream to read.
* @throws XMLStreamException
* If an error occurs reading events.
*/
public static final void skipElement(XMLEventReader reader) throws XMLStreamException {
copyElement(reader, null);
}
/**
* Copies an element and all its content from the provided event reader, to
* the provided event consumer. The event reader must be positioned before a
* start element event, or this method has no effect.
*
* @param reader
* The reader from which to read the events.
* @param consumer
* The destination for read events, or null to ignore
* all events.
* @throws XMLStreamException
* If an error occurs reading or writing the events.
*/
public static final void copyElement(XMLEventReader reader, XMLEventConsumer consumer)
throws XMLStreamException {
if (!reader.hasNext())
return;
XMLEvent event = reader.peek();
if (!event.isStartElement())
return;
int depth = 0;
do {
XMLEvent currEvt = reader.nextEvent();
if (currEvt.isStartElement()) {
depth++;
} else if (currEvt.isEndElement()) {
depth--;
}
if (consumer != null) {
consumer.add(currEvt);
}
} while (depth > 0 && reader.hasNext());
}
/**
* Skips all events within a StartElement until the matching
* EndElement is reached. This method assumes that the reader is
* positioned after the StartElement event, and when the method
* completes, the stream will be positioned before the EndElement
* event, but it will not consume the end tag.
*
* @param reader
* The event stream to read, positioned after the
* StartElement
* @throws XMLStreamException
* If an error occurs reading events.
*/
public static final void skipElementContent(XMLEventReader reader) throws XMLStreamException {
copyElementContent(reader, null);
}
/**
* Copies all events within a StartElement until the matching
* EndElement is reached. This method assumes that the reader is
* positioned after the StartElement event, and when the method
* completes, the stream will be positioned before the EndElement
* event, but it will not consume the end tag.
*
* @param reader
* The event stream to read, positioned after the
* StartElement
* @param consumer
* The destination for events read from teh stream, or
* null to ignore the events completely.
* @throws XMLStreamException
* If an error occurs reading events.
*/
public static final void copyElementContent(XMLEventReader reader, XMLEventConsumer consumer)
throws XMLStreamException {
if (!reader.hasNext())
return;
for (int depth = 1; true;) {
// peek and see if we're at the end element
XMLEvent currEvt = reader.peek();
if (currEvt.isEndElement()) {
depth--;
if (depth == 0) {
break;
}
} else if (currEvt.isStartElement()) {
depth++;
}
// consume the event
currEvt = reader.nextEvent();
if (consumer != null) {
consumer.add(currEvt);
}
}
}
/**
* Skips the complete content of the element at the specified reader's cursor.
* The reader's current event type must be START_ELEMENT, otherwise this
* method will have no effect. Upon completion, the reader's cursor will be at
* the END_ELEMENT event for the skipped element.
*
* @param reader
* An XML stream reader currently in the START_ELEMENT event.
*/
public static final void skipElement(XMLStreamReader reader) throws XMLStreamException {
if (reader.isStartElement()) {
skipElementContent(reader);
}
}
/**
* Skips an element's complete content. This method assumes that the
* START_ELEMENT has already be passed, and when it terminates,
* the stream will be positioned at the END_ELEMENT.
*
* @param reader
* The stream reader to read.
* @throws XMLStreamException
* If an error occurs reading the stream.
*/
public static final void skipElementContent(XMLStreamReader reader) throws XMLStreamException {
int depth = 0;
while (depth >= 0) {
reader.next();
if (reader.isStartElement()) {
depth++;
} else if (reader.isEndElement()) {
depth--;
}
}
}
/**
* Static utility method that throws an exception if the supplied reader's
* cursor doesn't point to a START_ELEMENT with the given name.
*
* @param reader
* The reader to test.
* @param name
* The name of the element to require.
* @throws XMLStreamException
* If the reader state is an element with the specified name.
*/
public static final void requireElement(XMLStreamReader reader, QName name)
throws XMLStreamException {
reader.require(XMLStreamReader.START_ELEMENT, name.getNamespaceURI(), name.getLocalPart());
}
/**
* Copies the content read from the specified source stream to the provided
* result stream. This method is exactly the same as calling
* {@link XMLEventWriter#add(XMLEventReader)}, and is provided only for
* completeness.
*
* @param reader
* The source stream.
* @param consumer
* The destination stream.
* @throws XMLStreamException
* If an error occurs copying the stream contents.
*/
public static final void copy(XMLEventReader reader, XMLEventConsumer consumer)
throws XMLStreamException {
if (consumer instanceof XMLEventWriter) {
copy(reader, (XMLEventWriter) consumer);
} else {
while (reader.hasNext()) {
consumer.add(reader.nextEvent());
}
}
}
/**
* Copies the content read from the specified source stream to the provided
* result stream. This method is exactly the same as calling
* {@link XMLEventWriter#add(XMLEventReader)}, and is provided only for
* completeness.
*
* @param reader
* The source stream.
* @param writer
* The destination stream.
* @throws XMLStreamException
* If an error occurs copying the stream contents.
*/
public static final void copy(XMLEventReader reader, XMLEventWriter writer)
throws XMLStreamException {
writer.add(reader);
}
/**
* Copies the content read from the specified source stream to the provided
* result stream.
*
* @param reader
* The source stream.
* @param writer
* The destination stream.
* @throws XMLStreamException
* If an error occurs copying the stream contents.
*/
public static final void copy(XMLStreamReader reader, XMLStreamWriter writer)
throws XMLStreamException {
XMLEventReader r = inputFactory.createXMLEventReader(reader);
XMLEventWriter w = new XMLStreamEventWriter(writer);
try {
w.add(r);
} finally {
// force any cached events to the underlying writer
w.flush();
}
}
/**
* Copies the content read from the specified source stream to the provided
* result stream.
*
* @param reader
* The source stream.
* @param writer
* The destination stream.
* @param factory
* An optional input factory used to create any intermediate streams.
* @throws XMLStreamException
* If an error occurs copying the stream contents.
*/
public static final void copy(XMLStreamReader reader, XMLStreamWriter writer,
XMLInputFactory factory) throws XMLStreamException {
if (factory == null) {
factory = inputFactory;
}
XMLEventReader r = factory.createXMLEventReader(reader);
XMLEventWriter w = new XMLStreamEventWriter(writer);
try {
w.add(r);
} finally {
// force any cached events to the underlying writer
w.flush();
}
}
/**
* Copies the content read from a TrAX {@link Source} to a StAX
* {@link XMLStreamWriter}.
*
* @param source
* The content source.
* @param writer
* The destination stream.
* @throws XMLStreamException
* If an error occurs copying the content to the stream.
*/
public static final void copy(Source source, XMLStreamWriter writer) throws XMLStreamException {
XMLStreamReader reader = inputFactory.createXMLStreamReader(source);
copy(reader, writer);
}
/**
* Copies the content read from a TrAX {@link Source} to a StAX
* {@link XMLEventWriter}.
*
* @param source
* The content source.
* @param writer
* The destination event stream.
* @throws XMLStreamException
* If an error occurs copying the content to the event stream.
*/
public static final void copy(Source source, XMLEventWriter writer) throws XMLStreamException {
XMLEventReader reader = inputFactory.createXMLEventReader(source);
copy(reader, writer);
}
/**
* Copies the content read from a StAX {@link XMLEventReader} to a TrAX
* {@link Result}.
*
* @param reader
* The source event stream.
* @param result
* The destination {@link Result}.
* @throws XMLStreamException
* If an error occurs copying the content to the result.
*/
public static final void copy(XMLEventReader reader, Result result) throws XMLStreamException {
XMLEventWriter writer = outputFactory.createXMLEventWriter(result);
copy(reader, writer);
// force any cached events to the result
writer.flush();
}
/**
* Copies the content read from a StAX {@link XMLStreamReader} to a TrAX
* {@link Result}.
*
* @param reader
* The source stream.
* @param result
* The destination {@link Result}.
* @throws XMLStreamException
* If an error occurs copying the content to the result.
*/
public static final void copy(XMLStreamReader reader, Result result) throws XMLStreamException {
XMLStreamWriter writer = outputFactory.createXMLStreamWriter(result);
copy(reader, writer);
// force any cached content to the result
writer.flush();
}
/**
* Utility method that throws an exception if the provided reader is not
* positioned before a StartElement event with the specified tag name.
*
* @param reader
* The reader to test.
* @param qname
* The required name of the start-tag. If null, any
* start tag is accepted.
* @throws XMLStreamException
* If an error occurs reading from the stream.
*/
public static final void requireStartElement(XMLEventReader reader, QName qname)
throws XMLStreamException {
if (reader.hasNext()) {
XMLEvent nextEvent = reader.peek();
if (nextEvent.isStartElement()) {
if (qname != null) {
StartElement start = nextEvent.asStartElement();
QName name = start.getName();
if (!name.equals(qname)) {
throw new XMLStreamException("Encountered unexpected element; expected " + qname
+ ", but found " + name);
}
}
} else {
throw new XMLStreamException("Encountered unexpected event; expected " + qname
+ " start-tag, but found event " + nextEvent);
}
} else {
throw new XMLStreamException("Encountered unexpected end of stream; expected element "
+ qname);
}
}
/**
* Constructs a new StartElement that merges the attributes and namespaces
* found in the specified StartElement, with the provided attributes. The
* returned StartElement will contain all the attributes and namespaces of the
* original, plus those defined in the map.
*
* @param tag
* The original StartElement
* @param attrs
* An iterator of Atributes to add to the element.
* @return A new StartElement that contains all the original attributes and
* namespaces, plus the provided attributes.
*/
public static StartElement mergeAttributes(StartElement tag, Iterator attrs,
XMLEventFactory factory) {
// create Attribute map
Map attributes = new HashMap();
// iterate through start tag's attributes
for (Iterator i = tag.getAttributes(); i.hasNext();) {
Attribute attr = (Attribute) i.next();
attributes.put(attr.getName(), attr);
}
// iterate through new attributes
while (attrs.hasNext()) {
Attribute attr = (Attribute) attrs.next();
attributes.put(attr.getName(), attr);
}
factory.setLocation(tag.getLocation());
QName tagName = tag.getName();
return factory.createStartElement(tagName.getPrefix(), tagName.getNamespaceURI(),
tagName.getLocalPart(), attributes.values().iterator(), tag.getNamespaces(),
tag.getNamespaceContext());
}
/**
* Reads the text content of an element. The reader should be positioned in
* front of a StartElement event, and will be read up to and including the end
* element tag.
*
* @param reader
* The event stream from which to read the element text.
* @param elemName
* The optional name of the element being read. If this paramter is
* non- null then an exception will be thrown if the
* element read doesn't have the same name.
* @return The text read from the element.
* @throws XMLStreamException
* If an error occurs reading the stream, or if the read element
* doesn't match the provided QName.
*/
public static final String readTextElement(XMLEventReader reader, QName elemName)
throws XMLStreamException {
if (elemName != null) {
requireStartElement(reader, elemName);
}
// read text
String text = reader.getElementText();
// consume the end tag
reader.nextEvent();
return text;
}
/**
* Advances the event stream until it encounters a start or end tag, but does
* not actaully read the event.
*
* @param reader
* The reader to peek.
* @return The next StartElement or EndElement event, retrieved using
* peek(), or null if the end of the stream
* was encountered before any tag event.
* @throws XMLStreamException
* If an error occurs reading the stream.
*/
public static final XMLEvent nextTag(XMLEventReader reader) throws XMLStreamException {
while (reader.hasNext()) {
XMLEvent nextEvent = reader.peek();
if (nextEvent.isStartElement() || nextEvent.isEndElement()) {
return nextEvent;
} else {
// eat the event.
reader.nextEvent();
}
}
return null;
}
/**
* Reads the events from the provided event stream until either a start or end
* tag is encountered. In the former case, the start tag will be returned, but
* if an end tag is encountered, null will be returned. After
* returning, the stream will be positioned just before the returned start
* element. The start element will not be consumed by this method.
*
* @param reader
* The event stream from which to read.
* @return The StartElement read from the stream, or null if an
* end tag was found first, or the stream ended before a start element
* was found.
* @throws XMLStreamException
* If an error occurs reading the stream.
*/
public static final StartElement nextElement(XMLEventReader reader) throws XMLStreamException {
return nextElement(reader, null);
}
/**
* Reads the events from the provided event stream until either a start or end
* tag is encountered. In the former case, the start tag will be returned if
* it matches the specified QName, but if it doesn't match, an end tag is
* encountered, or the stream ends, null will be returned. After
* returning, the stream will be positioned just before the start element. The
* start element will not be consumed by this method.
*
* @param reader
* The event stream from which to read.
* @param name
* The name of the element to read, or null to read any
* start tag.
* @return The StartElement read from the stream, or null if the
* encountered start tag didn't match the specified QName, an end tag
* was found first, or the stream ended before a start element was
* found.
* @throws XMLStreamException
* If an error occurs reading the stream.
*/
public static final StartElement nextElement(XMLEventReader reader, QName name)
throws XMLStreamException {
while (reader.hasNext()) {
XMLEvent nextEvent = reader.peek();
if (nextEvent.isStartElement()) {
StartElement start = nextEvent.asStartElement();
if (name == null || start.getName().equals(name)) {
return start;
} else {
break;
}
} else if (nextEvent.isEndElement()) {
break;
} else {
// consume the event.
reader.nextEvent();
}
}
return null;
}
}
