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/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j.io;

import java.io.InputStream;
import java.io.Reader;
import java.util.Iterator;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.Characters;
import javax.xml.stream.events.Comment;
import javax.xml.stream.events.EndElement;
import javax.xml.stream.events.EntityReference;
import javax.xml.stream.events.Namespace;
import javax.xml.stream.events.ProcessingInstruction;
import javax.xml.stream.events.StartDocument;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.events.XMLEvent;

import org.dom4j.CharacterData;
import org.dom4j.Document;
import org.dom4j.DocumentFactory;
import org.dom4j.Element;
import org.dom4j.Entity;
import org.dom4j.Node;

/**
 * Reads a DOM4J {@link Document}, as well as other {@link Node}s, from a StAX
 * {@link XMLEventReader}.
 * 
 * @author Christian Niles
 */
public class STAXEventReader {
    /** Reference to the DocumentFactory used to build DOM4J nodes. */
    private DocumentFactory factory;

    /** A StAX input factory, used to construct streams from IO streams. */
    private XMLInputFactory inputFactory = XMLInputFactory.newInstance();

    /**
     * Constructs a default STAXEventReader instance with a
     * default {@link DocumentFactory}.
     */
    public STAXEventReader() {
        this.factory = DocumentFactory.getInstance();
    }

    /**
     * Constructs a STAXEventReader instance that uses the
     * specified {@link DocumentFactory}to construct DOM4J {@link Node}s.
     * 
     * @param factory
     *            The DocumentFactory to use when constructing DOM4J nodes, or
     *            null if a default should be used.
     */
    public STAXEventReader(DocumentFactory factory) {
        if (factory != null) {
            this.factory = factory;
        } else {
            this.factory = DocumentFactory.getInstance();
        }
    }

    /**
     * Sets the DocumentFactory to be used when constructing DOM4J nodes.
     * 
     * @param documentFactory
     *            The DocumentFactory to use when constructing DOM4J nodes, or
     *            null if a default should be used.
     */
    public void setDocumentFactory(DocumentFactory documentFactory) {
        if (documentFactory != null) {
            this.factory = documentFactory;
        } else {
            this.factory = DocumentFactory.getInstance();
        }
    }

    /**
     * Constructs a StAX event stream from the provided I/O stream and reads a
     * DOM4J document from it.
     * 
     * @param is
     *            The I/O stream from which the Document will be read.
     * 
     * @return The Document that was read from the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs reading content from the stream.
     */
    public Document readDocument(InputStream is) throws XMLStreamException {
        return readDocument(is, null);
    }

    /**
     * Constructs a StAX event stream from the provided I/O character stream and
     * reads a DOM4J document from it.
     * 
     * @param reader
     *            The character stream from which the Document will be read.
     * 
     * @return The Document that was read from the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs reading content from the stream.
     */
    public Document readDocument(Reader reader) throws XMLStreamException {
        return readDocument(reader, null);
    }

    /**
     * Constructs a StAX event stream from the provided I/O stream and reads a
     * DOM4J document from it.
     * 
     * @param is
     *            The I/O stream from which the Document will be read.
     * @param systemId
     *            A system id used to resolve entities.
     * 
     * @return The Document that was read from the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs reading content from the stream.
     */
    public Document readDocument(InputStream is, String systemId)
            throws XMLStreamException {
        XMLEventReader eventReader = inputFactory.createXMLEventReader(
                systemId, is);

        try {
            return readDocument(eventReader);
        } finally {
            eventReader.close();
        }
    }

    /**
     * Constructs a StAX event stream from the provided I/O character stream and
     * reads a DOM4J document from it.
     * 
     * @param reader
     *            The character stream from which the Document will be read.
     * @param systemId
     *            A system id used to resolve entities.
     * 
     * @return The Document that was read from the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs reading content from the stream.
     */
    public Document readDocument(Reader reader, String systemId)
            throws XMLStreamException {
        XMLEventReader eventReader = inputFactory.createXMLEventReader(
                systemId, reader);

        try {
            return readDocument(eventReader);
        } finally {
            eventReader.close();
        }
    }

    /**
     * Reads a {@link Node}from the event stream. If the next event is a
     * {@link StartElement}, all events until the closing {@link EndElement}
     * will be read, and the resulting nodes will be added to the returned
     * {@link Element}.
     * 
     * 

* Pre-Conditions : The stream must be positioned before an * event other than an EndElement,EndDocument, * or any DTD-related events, which are not currently supported. *

* * @param reader * The reader from which events will be read. * * @return A DOM4J {@link Node}constructed from the read events. * * @throws XMLStreamException * If an error occurs reading from the stream, or the stream was * positioned before an unsupported event. */ public Node readNode(XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event.isStartElement()) { return readElement(reader); } else if (event.isCharacters()) { return readCharacters(reader); } else if (event.isStartDocument()) { return readDocument(reader); } else if (event.isProcessingInstruction()) { return readProcessingInstruction(reader); } else if (event.isEntityReference()) { return readEntityReference(reader); } else if (event.isAttribute()) { return readAttribute(reader); } else if (event.isNamespace()) { return readNamespace(reader); } else { throw new XMLStreamException("Unsupported event: " + event); } } /** * Reads a DOM4J {@link Document}from the provided stream. The stream * should be positioned at the start of a document, or before a {@link * StartElement} event. * * @param reader * The event stream from which to read the {@link Document}. * * @return The {@link Document}that was read from the stream. * * @throws XMLStreamException * If an error occurs reading events from the stream. */ public Document readDocument(XMLEventReader reader) throws XMLStreamException { Document doc = null; while (reader.hasNext()) { XMLEvent nextEvent = reader.peek(); int type = nextEvent.getEventType(); switch (type) { case XMLStreamConstants.START_DOCUMENT: StartDocument event = (StartDocument) reader.nextEvent(); if (doc == null) { // create document if (event.encodingSet()) { String encodingScheme = event .getCharacterEncodingScheme(); doc = factory.createDocument(encodingScheme); } else { doc = factory.createDocument(); } } else { // duplicate or misplaced xml declaration String msg = "Unexpected StartDocument event"; throw new XMLStreamException(msg, event.getLocation()); } break; case XMLStreamConstants.END_DOCUMENT: case XMLStreamConstants.SPACE: case XMLStreamConstants.CHARACTERS: // skip end document and space outside the root element reader.nextEvent(); break; default: if (doc == null) { // create document doc = factory.createDocument(); } Node n = readNode(reader); doc.add(n); } } return doc; } /** * Reads a DOM4J Element from the provided event stream. The stream must be * positioned before an {@link StartElement}event. In addition to the * initial start event, all events up to and including the closing {@link * EndElement} will be read, and included with the returned element. * * @param eventReader * The event stream from which to read the Element. * * @return The Element that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before a {@linkStartElement}event. */ public Element readElement(XMLEventReader eventReader) throws XMLStreamException { XMLEvent event = eventReader.peek(); if (event.isStartElement()) { // advance the reader and get the StartElement event StartElement startTag = eventReader.nextEvent().asStartElement(); Element elem = createElement(startTag); // read element content while (true) { if (!eventReader.hasNext()) { String msg = "Unexpected end of stream while reading" + " element content"; throw new XMLStreamException(msg); } XMLEvent nextEvent = eventReader.peek(); if (nextEvent.isEndElement()) { EndElement endElem = eventReader.nextEvent().asEndElement(); if (!endElem.getName().equals(startTag.getName())) { throw new XMLStreamException("Expected " + startTag.getName() + " end-tag, but found" + endElem.getName()); } break; } Node child = readNode(eventReader); elem.add(child); } return elem; } else { throw new XMLStreamException("Expected Element event, found: " + event); } } /** * Constructs a DOM4J Attribute from the provided event stream. The stream * must be positioned before an {@link Attribute}event. * * @param reader * The event stream from which to read the Attribute. * * @return The Attribute that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before an {@linkAttribute}event. */ public org.dom4j.Attribute readAttribute(XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event.isAttribute()) { Attribute attr = (Attribute) reader.nextEvent(); return createAttribute(null, attr); } else { throw new XMLStreamException("Expected Attribute event, found: " + event); } } /** * Constructs a DOM4J Namespace from the provided event stream. The stream * must be positioned before a {@link Namespace}event. * * @param reader * The event stream from which to read the Namespace. * * @return The Namespace that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before a {@linkNamespace}event. */ public org.dom4j.Namespace readNamespace(XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event.isNamespace()) { Namespace ns = (Namespace) reader.nextEvent(); return createNamespace(ns); } else { throw new XMLStreamException("Expected Namespace event, found: " + event); } } /** * Constructs a DOM4J Text or CDATA section from the provided event stream. * The stream must be positioned before a {@link Characters}event. * * @param reader * The event stream from which to read the Text or CDATA. * * @return The Text or CDATA that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before a {@linkCharacters}event. */ public CharacterData readCharacters(XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event.isCharacters()) { Characters characters = reader.nextEvent().asCharacters(); return createCharacterData(characters); } else { throw new XMLStreamException("Expected Characters event, found: " + event); } } /** * Constructs a DOM4J Comment from the provided event stream. The stream * must be positioned before a {@link Comment}event. * * @param reader * The event stream from which to read the Comment. * * @return The Comment that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before a {@linkComment}event. */ public org.dom4j.Comment readComment(XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event instanceof Comment) { return createComment((Comment) reader.nextEvent()); } else { throw new XMLStreamException("Expected Comment event, found: " + event); } } /** * Constructs a DOM4J Entity from the provided event stream. The stream must * be positioned before an {@link EntityReference}event. * * @param reader * The event stream from which to read the {@link * EntityReference}. * * @return The {@link org.dom4j.Entity}that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before an {@linkEntityReference} * event. */ public Entity readEntityReference(XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event.isEntityReference()) { EntityReference entityRef = (EntityReference) reader.nextEvent(); return createEntity(entityRef); } else { throw new XMLStreamException("Expected EntityRef event, found: " + event); } } /** * Constructs a DOM4J ProcessingInstruction from the provided event stream. * The stream must be positioned before a {@link ProcessingInstruction} * event. * * @param reader * The event stream from which to read the ProcessingInstruction. * * @return The ProcessingInstruction that was read from the stream. * * @throws XMLStreamException * If an error occured reading events from the stream, or the * stream was not positioned before a {@link * ProcessingInstruction} event. */ public org.dom4j.ProcessingInstruction readProcessingInstruction( XMLEventReader reader) throws XMLStreamException { XMLEvent event = reader.peek(); if (event.isProcessingInstruction()) { ProcessingInstruction pi = (ProcessingInstruction) reader .nextEvent(); return createProcessingInstruction(pi); } else { throw new XMLStreamException("Expected PI event, found: " + event); } } /** * Constructs a new DOM4J Element from the provided StartElement event. All * attributes and namespaces will be added to the returned element. * * @param startEvent * The StartElement event from which to construct the new DOM4J * Element. * * @return The Element constructed from the provided StartElement event. */ public Element createElement(StartElement startEvent) { QName qname = startEvent.getName(); org.dom4j.QName elemName = createQName(qname); Element elem = factory.createElement(elemName); // create attributes for (Iterator i = startEvent.getAttributes(); i.hasNext();) { Attribute attr = (Attribute) i.next(); elem.addAttribute(createQName(attr.getName()), attr.getValue()); } // create namespaces for (Iterator i = startEvent.getNamespaces(); i.hasNext();) { Namespace ns = (Namespace) i.next(); elem.addNamespace(ns.getPrefix(), ns.getNamespaceURI()); } return elem; } /** * Constructs a new DOM4J Attribute from the provided StAX Attribute event. * * @param elem * DOCUMENT ME! * @param attr * The Attribute event from which to construct the new DOM4J * Attribute. * * @return The Attribute constructed from the provided Attribute event. */ public org.dom4j.Attribute createAttribute(Element elem, Attribute attr) { return factory.createAttribute(elem, createQName(attr.getName()), attr .getValue()); } /** * Constructs a new DOM4J Namespace from the provided StAX Namespace event. * * @param ns * The Namespace event from which to construct the new DOM4J * Namespace. * * @return The Namespace constructed from the provided Namespace event. */ public org.dom4j.Namespace createNamespace(Namespace ns) { return factory.createNamespace(ns.getPrefix(), ns.getNamespaceURI()); } /** * Constructs a new DOM4J Text or CDATA object from the provided Characters * event. * * @param characters * The Characters event from which to construct the new DOM4J * Text or CDATA object. * * @return The Text or CDATA object constructed from the provided Characters * event. */ public CharacterData createCharacterData(Characters characters) { String data = characters.getData(); if (characters.isCData()) { return factory.createCDATA(data); } else { return factory.createText(data); } } /** * Constructs a new DOM4J Comment from the provided StAX Comment event. * * @param comment * The Comment event from which to construct the new DOM4J * Comment. * * @return The Comment constructed from the provided Comment event. */ public org.dom4j.Comment createComment(Comment comment) { return factory.createComment(comment.getText()); } /** * Constructs a new DOM4J Entity from the provided StAX EntityReference * event. * * @param entityRef * The EntityReference event from which to construct the new * DOM4J Entity. * * @return The Entity constructed from the provided EntityReference event. */ public org.dom4j.Entity createEntity(EntityReference entityRef) { return factory.createEntity(entityRef.getName(), entityRef .getDeclaration().getReplacementText()); } /** * Constructs a new DOM4J ProcessingInstruction from the provided StAX * ProcessingInstruction event. * * @param pi * The ProcessingInstruction event from which to construct the * new DOM4J ProcessingInstruction. * * @return The ProcessingInstruction constructed from the provided * ProcessingInstruction event. */ public org.dom4j.ProcessingInstruction createProcessingInstruction( ProcessingInstruction pi) { return factory .createProcessingInstruction(pi.getTarget(), pi.getData()); } /** * Constructs a new DOM4J QName from the provided JAXP QName. * * @param qname * The JAXP QName from which to create a DOM4J QName. * * @return The newly constructed DOM4J QName. */ public org.dom4j.QName createQName(QName qname) { return factory.createQName(qname.getLocalPart(), qname.getPrefix(), qname.getNamespaceURI()); } } /* * Redistribution and use of this software and associated documentation * ("Software"), with or without modification, are permitted provided that the * following conditions are met: * * 1. Redistributions of source code must retain copyright statements and * notices. Redistributions must also contain a copy of this document. * * 2. 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. * * 3. The name "DOM4J" must not be used to endorse or promote products derived * from this Software without prior written permission of MetaStuff, Ltd. For * written permission, please contact [email protected]. * * 4. Products derived from this Software may not be called "DOM4J" nor may * "DOM4J" appear in their names without prior written permission of MetaStuff, * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd. * * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org * * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESSED 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 METASTUFF, LTD. OR ITS 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. * * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved. */




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