staxeventwriter.java

解决如何把XML应用到JAVA里问题

/*
 * 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.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.StringWriter;
import java.io.Writer;
import java.util.Iterator;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLEventFactory;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Characters;
import javax.xml.stream.events.DTD;
import javax.xml.stream.events.EndDocument;
import javax.xml.stream.events.EndElement;
import javax.xml.stream.events.EntityReference;
import javax.xml.stream.events.ProcessingInstruction;
import javax.xml.stream.events.StartDocument;
import javax.xml.stream.events.StartElement;
import javax.xml.stream.util.XMLEventConsumer;

import org.dom4j.Attribute;
import org.dom4j.Branch;
import org.dom4j.CDATA;
import org.dom4j.Comment;
import org.dom4j.Document;
import org.dom4j.DocumentType;
import org.dom4j.Element;
import org.dom4j.Entity;
import org.dom4j.Namespace;
import org.dom4j.Node;
import org.dom4j.Text;

/**
 * Writes DOM4J {@link Node}s to a StAX event stream. In addition the
 * <code>createXXX</code> methods are provided to directly create STAX events
 * from DOM4J nodes.
 * 
 * @author Christian Niles
 */
public class STAXEventWriter {
    /** The event stream to which events are written. */
    private XMLEventConsumer consumer;

    /** The event factory used to construct events. */
    private XMLEventFactory factory = XMLEventFactory.newInstance();

    private XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();

    public STAXEventWriter() {
    }

    /**
     * Constructs a <code>STAXEventWriter</code> that writes events to the
     * provided file.
     * 
     * @param file
     *            The file to which events will be written.
     * 
     * @throws XMLStreamException
     *             If an error occurs creating an event writer from the file.
     * @throws IOException
     *             If an error occurs openin the file for writing.
     */
    public STAXEventWriter(File file) throws XMLStreamException, IOException {
        consumer = outputFactory.createXMLEventWriter(new FileWriter(file));
    }

    /**
     * Constructs a <code>STAXEventWriter</code> that writes events to the
     * provided character stream.
     * 
     * @param writer
     *            The character stream to which events will be written.
     * 
     * @throws XMLStreamException
     *             If an error occurs constructing an event writer from the
     *             character stream.
     */
    public STAXEventWriter(Writer writer) throws XMLStreamException {
        consumer = outputFactory.createXMLEventWriter(writer);
    }

    /**
     * Constructs a <code>STAXEventWriter</code> that writes events to the
     * provided stream.
     * 
     * @param stream
     *            The output stream to which events will be written.
     * 
     * @throws XMLStreamException
     *             If an error occurs constructing an event writer from the
     *             stream.
     */
    public STAXEventWriter(OutputStream stream) throws XMLStreamException {
        consumer = outputFactory.createXMLEventWriter(stream);
    }

    /**
     * Constructs a <code>STAXEventWriter</code> that writes events to the
     * provided event stream.
     * 
     * @param consumer
     *            The event stream to which events will be written.
     */
    public STAXEventWriter(XMLEventConsumer consumer) {
        this.consumer = consumer;
    }

    /**
     * Returns a reference to the underlying event consumer to which events are
     * written.
     * 
     * @return The underlying event consumer to which events are written.
     */
    public XMLEventConsumer getConsumer() {
        return consumer;
    }

    /**
     * Sets the underlying event consumer to which events are written.
     * 
     * @param consumer
     *            The event consumer to which events should be written.
     */
    public void setConsumer(XMLEventConsumer consumer) {
        this.consumer = consumer;
    }

    /**
     * Returns a reference to the event factory used to construct STAX events.
     * 
     * @return The event factory used to construct STAX events.
     */
    public XMLEventFactory getEventFactory() {
        return factory;
    }

    /**
     * Sets the event factory used to construct STAX events.
     * 
     * @param eventFactory
     *            The new event factory.
     */
    public void setEventFactory(XMLEventFactory eventFactory) {
        this.factory = eventFactory;
    }

    /**
     * Writes a DOM4J {@link Node}to the stream. This method is simply a
     * gateway to the overloaded methods such as {@link#writeElement(Element)}.
     * 
     * @param n
     *            The DOM4J {@link Node}to write to the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs writing to the stream.
     */
    public void writeNode(Node n) throws XMLStreamException {
        switch (n.getNodeType()) {
            case Node.ELEMENT_NODE:
                writeElement((Element) n);

                break;

            case Node.TEXT_NODE:
                writeText((Text) n);

                break;

            case Node.ATTRIBUTE_NODE:
                writeAttribute((Attribute) n);

                break;

            case Node.NAMESPACE_NODE:
                writeNamespace((Namespace) n);

                break;

            case Node.COMMENT_NODE:
                writeComment((Comment) n);

                break;

            case Node.CDATA_SECTION_NODE:
                writeCDATA((CDATA) n);

                break;

            case Node.PROCESSING_INSTRUCTION_NODE:
                writeProcessingInstruction((org.dom4j.ProcessingInstruction) n);

                break;

            case Node.ENTITY_REFERENCE_NODE:
                writeEntity((Entity) n);

                break;

            case Node.DOCUMENT_NODE:
                writeDocument((Document) n);

                break;

            case Node.DOCUMENT_TYPE_NODE:
                writeDocumentType((DocumentType) n);

                break;

            default:
                throw new XMLStreamException("Unsupported DOM4J Node: " + n);
        }
    }

    /**
     * Writes each child node within the provided {@link Branch}instance. This
     * method simply iterates through the {@link Branch}'s nodes and calls
     * {@link #writeNode(Node)}.
     * 
     * @param branch
     *            The node whose children will be written to the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs writing to the stream.
     */
    public void writeChildNodes(Branch branch) throws XMLStreamException {
        for (int i = 0, s = branch.nodeCount(); i < s; i++) {
            Node n = branch.node(i);
            writeNode(n);
        }
    }

    /**
     * Writes a DOM4J {@link Element}node and its children to the stream.
     * 
     * @param elem
     *            The {@link Element}node to write to the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs writing to the stream.
     */
    public void writeElement(Element elem) throws XMLStreamException {
        consumer.add(createStartElement(elem));
        writeChildNodes(elem);
        consumer.add(createEndElement(elem));
    }

    /**
     * Constructs a STAX {@link StartElement}event from a DOM4J {@link
     * Element}.
     * 
     * @param elem
     *            The {@link Element}from which to construct the event.
     * 
     * @return The newly constructed {@link StartElement}event.
     */
    public StartElement createStartElement(Element elem) {
        // create name
        QName tagName = createQName(elem.getQName());

        // create attribute & namespace iterators
        Iterator attrIter = new AttributeIterator(elem.attributeIterator());
        Iterator nsIter = new NamespaceIterator(elem.declaredNamespaces()
                .iterator());

        // create start event
        return factory.createStartElement(tagName, attrIter, nsIter);
    }

    /**
     * Constructs a STAX {@link EndElement}event from a DOM4J {@link Element}.
     * 
     * @param elem
     *            The {@link Element}from which to construct the event.
     * 
     * @return The newly constructed {@link EndElement}event.
     */
    public EndElement createEndElement(Element elem) {
        QName tagName = createQName(elem.getQName());
        Iterator nsIter = new NamespaceIterator(elem.declaredNamespaces()
                .iterator());

        return factory.createEndElement(tagName, nsIter);
    }

    /**
     * Writes a DOM4J {@link Attribute}to the stream.
     * 
     * @param attr
     *            The {@link Attribute}to write to the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs writing to the stream.
     */
    public void writeAttribute(Attribute attr) throws XMLStreamException {
        consumer.add(createAttribute(attr));
    }

    /**
     * Constructs a STAX {@link javax.xml.stream.events.Attribute}event from a
     * DOM4J {@link Attribute}.
     * 
     * @param attr
     *            The {@link Attribute}from which to construct the event.
     * 
     * @return The newly constructed {@link javax.xml.stream.events.Attribute}
     *         event.
     */
    public javax.xml.stream.events.Attribute createAttribute(Attribute attr) {
        QName attrName = createQName(attr.getQName());
        String value = attr.getValue();

        return factory.createAttribute(attrName, value);
    }

    /**
     * Writes a DOM4J {@link Namespace}to the stream.
     * 
     * @param ns
     *            The {@link Namespace}to write to the stream.
     * 
     * @throws XMLStreamException
     *             If an error occurs writing to the stream.
     */
    public void writeNamespace(Namespace ns) throws XMLStreamException {
        consumer.add(createNamespace(ns));
    }

    /**
     * Constructs a STAX {@link javax.xml.stream.events.Namespace}event from a
     * DOM4J {@link Namespace}.
     *