SaxWriter.java

/*
 * Copyright 2006 Helsinki Institute for Information Technology
 * 
 * This file is a part of Fuego middleware. Fuego middleware is free software; you can redistribute
 * it and/or modify it under the terms of the MIT license, included as the file MIT-LICENSE in the
 * Fuego middleware source distribution. If you did not receive the MIT license with the
 * distribution, write to the Fuego Core project at fuego-core-users@hoslab.cs.helsinki.fi.
 */

package fuegocore.util.xas;

import java.util.Map;
import java.util.HashMap;
import java.io.OutputStream;
import java.io.IOException;

import fc.util.log.Log;

import org.xml.sax.ContentHandler;
import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;

import org.xmlpull.v1.XmlSerializer;

/**
 * A wrapper class to write with SAX events with XmlPull. This class wraps a
 * <code>XmlSerializer</code> and implements the SAX {@link ContentHandler} interface, which is
 * useful for output. The intent is to allow legacy SAX applications to use an XmlPull-based
 * serializer without altering their own code. New classes are recommended to use the
 * {@link EventSequence} interface and its implementing classes to handle XML.
 */
public class SaxWriter implements ContentHandler {

    protected XmlSerializer target;
    private Map prefixes = new HashMap();


    public SaxWriter(XmlSerializer target) {
        this(target, null);
    }


    public SaxWriter(XmlSerializer target, OutputStream os) {
        Log.debug("Constructor: target=" + target + ", os=" + os);
        this.target = target;
        if (os != null) {
            try {
                target.setOutput(os, "ISO-8859-1");
            } catch (IOException ex) {
                /*
                 * It is nonsensical for this method to throw exceptions, since this should only
                 * prepare for output, not actually output anything.
                 */
            }
        }
    }


    public void setDocumentLocator(Locator locator) {
    }


    public void startDocument() throws SAXException {
        Log.debug("startDocument()");
        if (target != null) {
            try {
                target.startDocument("ISO-8859-1", null);
            } catch (IOException ex) {
                throw new SAXException(ex);
            }
        }
    }


    public void endDocument() throws SAXException {
        Log.debug("endDocument()");
        if (target != null) {
            try {
                target.endDocument();
                target.flush();
            } catch (IOException ex) {
                throw new SAXException(ex);
            }
        }
    }


    public void startPrefixMapping(String prefix, String uri) throws SAXException {
        Log.debug("startPrefixMapping(" + prefix + ", " + uri + ")");
        prefixes.put(prefix, uri);
        if (target != null) {
            try {
                target.setPrefix(prefix, uri);
            } catch (IOException ex) {
                throw new SAXException(ex);
            }
        }
    }


    public void endPrefixMapping(String prefix) throws SAXException {
        Log.debug("endPrefixMapping(" + prefix + ")");
        prefixes.remove(prefix);
    }


    public void startElement(String namespaceURI, String localName, String qName,
                             Attributes attributes) throws SAXException {
        Log.debug("startElement(" + namespaceURI + ", " + localName + ", " + qName + ")");
        if (target != null) {
            try {
                if (localName == null || localName.equals("")) {
                    int index = qName.indexOf(':');
                    if (index >= 0) {
                        String uri = (String) prefixes.get(qName.substring(0, index));
                        if (uri != null) {
                            namespaceURI = uri;
                        }
                    }
                    localName = qName.substring(index + 1);
                }
                target.startTag(namespaceURI, localName);
                if (attributes != null) {
                    int length = attributes.getLength();
                    for (int i = 0; i < length; i++) {
                        String localAttName = attributes.getLocalName(i);
                        String attUri = attributes.getURI(i);
                        String attQName = attributes.getQName(i);
                        if (localAttName == null || localAttName.length() == 0) {
                            int index = attQName.indexOf(':');
                            if (index >= 0) {
                                String uri = (String) prefixes.get(attQName.substring(0, index));
                                if (uri != null) {
                                    attUri = uri;
                                }
                            }
                            localAttName = attQName.substring(index + 1);
                        }
                        target.attribute(attUri, localAttName, attributes.getValue(i));
                    }
                }
            } catch (IOException ex) {
                throw new SAXException(ex);
            }
        }
    }


    public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
        Log.debug("endElement(" + namespaceURI + ", " + localName + ", " + qName + ")");
        if (target != null) {
            try {
                if (localName == null || localName.equals("")) {
                    int index = qName.indexOf(':');
                    if (index >= 0) {
                        String uri = (String) prefixes.get(qName.substring(0, index));
                        if (uri != null) {
                            namespaceURI = uri;
                        }
                    }
                    localName = qName.substring(index + 1);
                }
                target.endTag(namespaceURI, localName);
            } catch (IOException ex) {
                throw new SAXException(ex);
            }
        }
    }


    public void characters(char[] ch, int start, int length) throws SAXException {
        Log.debug("characters(" + new String(ch, start, length) + ")");
        if (target != null) {
            try {
                target.text(ch, start, length);
            } catch (IOException ex) {
                throw new SAXException(ex);
            }
        }
    }


    public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {
    }


    public void processingInstruction(String target, String data) throws SAXException {
    }


    public void skippedEntity(String name) throws SAXException {
    }

}