com.topologi.diffx.load.SAXRecorder Maven / Gradle / Ivy
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/*
* This file is part of the DiffX library.
*
* For licensing information please see the file license.txt included in the release.
* A copy of this licence can also be found at
* http://www.opensource.org/licenses/artistic-license-2.0.php
*/
package com.topologi.diffx.load;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.xml.sax.Attributes;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;
import com.topologi.diffx.config.DiffXConfig;
import com.topologi.diffx.event.AttributeEvent;
import com.topologi.diffx.event.CloseElementEvent;
import com.topologi.diffx.event.OpenElementEvent;
import com.topologi.diffx.event.TextEvent;
import com.topologi.diffx.event.impl.EventFactory;
import com.topologi.diffx.event.impl.ProcessingInstructionEvent;
import com.topologi.diffx.load.text.TextTokenizer;
import com.topologi.diffx.load.text.TokenizerFactory;
import com.topologi.diffx.sequence.EventSequence;
/**
* Records the SAX events in an {@link com.topologi.diffx.sequence.EventSequence}.
*
* It is possible to specify the name of the XML reader implementation class.
* By default this class will try to use the Crimson parser
* org.apache.crimson.parser.XMLReaderImpl.
*
*
The XML reader implementation must support the following features settings
*
* http://xml.org/sax/features/validation => false
* http://xml.org/sax/features/namespaces => true | false
* http://xml.org/sax/features/namespace-prefixes => true | false
*
*
* @author Christophe Lauret
* @author Jean-Baptiste Reure
*
* @version 17 October 2006
*/
public final class SAXRecorder implements XMLRecorder {
// static variables -------------------------------------------------------------------------------
/**
* The XML reader.
*/
private static XMLReader reader;
/**
* The default XML reader in use.
*/
private static final String DEFAULT_XML_READER;
static {
String className;
try {
className = XMLReaderFactory.createXMLReader().getClass().getName();
} catch (SAXException ex) {
// FIXME: Exception handling!!!
// className = XMLReaderImpl.class.getName();
className = "";
}
DEFAULT_XML_READER = className;
}
/**
* The XML reader class in use (set to the deafult XML reader).
*/
private static String readerClassName = DEFAULT_XML_READER;
/**
* Indicates whether a new reader instance should be created because the specified class name
* has changed.
*/
private static boolean newReader = true;
// class attributes -------------------------------------------------------------------------------
/**
* The DiffX configuration to use
*/
private DiffXConfig config = new DiffXConfig();
/**
* The sequence of event for this recorder.
*/
protected transient EventSequence sequence;
// methods implementing XMLRecorder -------------------------------------------------------
/**
* Runs the recorder on the specified file.
*
* This method will count on the {@link InputSource} to guess the correct encoding.
*
* @param file The file to process.
*
* @return The recorded sequence of events.
*
* @throws LoadingException If thrown while parsing.
* @throws IOException Should I/O error occur.
*/
public EventSequence process(File file) throws LoadingException, IOException {
InputStream in = new BufferedInputStream(new FileInputStream(file));
EventSequence seq = null;
seq = process(new InputSource(in));
in.close();
in = null;
return seq;
}
/**
* Runs the recorder on the specified string.
*
*
This method is provided for convenience. It is best to only use this method for
* short strings.
*
* @param xml The XML string to process.
*
* @return The recorded sequence of events.
*
* @throws LoadingException If thrown while parsing.
* @throws IOException Should I/O error occur.
*/
public EventSequence process(String xml) throws LoadingException, IOException {
return this.process(new InputSource(new StringReader(xml)));
}
/**
* Runs the recorder on the specified input source.
*
* @param is The input source.
*
* @return The recorded sequence of events.
*
* @throws LoadingException If thrown whilst parsing.
* @throws IOException Should I/O error occur.
*/
public EventSequence process(InputSource is) throws LoadingException, IOException {
if (reader == null || newReader) {
init();
}
reader.setContentHandler(new RecorderHandler());
reader.setErrorHandler(new RecorderErrorHandler());
try {
reader.setFeature("http://xml.org/sax/features/namespaces", this.config.isNamespaceAware());
reader.setFeature("http://xml.org/sax/features/namespace-prefixes", this.config.isReportPrefixDifferences());
reader.parse(is);
} catch (SAXException ex) {
throw new LoadingException(ex);
}
return this.sequence;
}
/**
* Returns the configuration used by this recorder.
*
* @return the configuration used by this recorder.
*/
public DiffXConfig getConfig() {
return this.config;
}
/**
* Sets the configuration used by this recorder.
*
* @param config The configuration used by this recorder.
*/
public void setConfig(DiffXConfig config) {
this.config = config;
}
// other methods ------------------------------------------------------------------------------
/**
* Returns the name XMLReader class used by the SAXRecorders.
*
* @return the name XMLReader class used by the SAXRecorders.
*/
public static String getXMLReaderClass() {
return readerClassName;
}
/**
* Sets the name of the XML reader class to use.
*
*
Use null to reset the XML reader class and use the default XML reader.
*
*
A new reader will be created only if the specified class is different from the current one.
*
* @param className The name of the XML reader class to use;
* or null to reset the XML reader.
*/
public static void setXMLReaderClass(String className) {
// if the className is null reset to default
if (className == null) {
className = DEFAULT_XML_READER;
}
// reload only if different from the current one.
newReader = !className.equals(readerClassName);
readerClassName = className;
}
/**
* Initialises the XML reader using the defined class name.
*
* @throws LoadingException If one of the features could not be set.
*/
private static void init() throws LoadingException {
try {
reader = XMLReaderFactory.createXMLReader(readerClassName);
reader.setFeature("http://xml.org/sax/features/validation", false);
} catch (SAXException ex) {
throw new LoadingException(ex);
}
}
// static inner class for processing the XML files --------------------------------------------
/**
* A SAX2 handler that records XML events.
*
*
This class is an inner class as there is no reason to expose its method to the
* public API.
*
* @author Christophe Lauret, Jean-Baptiste Reure
* @version 27 April 2005
*/
private final class RecorderHandler extends DefaultHandler {
/**
* A buffer for character data.
*/
private final StringBuffer ch = new StringBuffer();
/**
* The comparator in order to sort attribute correctly.
*/
private final AttributeComparator comparator = new AttributeComparator();
/**
* The weight of the current element.
*/
private transient int currentWeight = -1;
/**
* The last open element event, should only contain OpenElementEvents.
*/
private transient List openElements = new ArrayList();
/**
* The stack of weight, should only contain Integer.
*/
private transient List weights = new ArrayList();
/**
* The factory that will produce events according to the configuration.
*/
private transient EventFactory efactory;
/**
* The text tokenizer according to the configuration.
*/
private transient TextTokenizer tokenizer;
/**
* @see org.xml.sax.ContentHandler#startDocument()
*/
@Override
public void startDocument() {
SAXRecorder.this.sequence = new EventSequence();
this.efactory = new EventFactory(SAXRecorder.this.config.isNamespaceAware());
this.tokenizer = TokenizerFactory.get(SAXRecorder.this.config);
SAXRecorder.this.sequence.mapPrefix("http://www.w3.org/XML/1998/namespace", "xml");
}
/**
* {@inheritDoc}
*/
@Override
public void startPrefixMapping(String prefix, String uri) throws SAXException {
SAXRecorder.this.sequence.mapPrefix(uri, prefix);
}
/**
* {@inheritDoc}
*/
@Override
public void startElement(String uri, String localName, String qName, Attributes atts) {
recordCharacters();
if (this.currentWeight > 0) {
this.weights.add(new Integer(this.currentWeight));
}
this.currentWeight = 1;
OpenElementEvent open = this.efactory.makeOpenElement(uri, localName, qName);
this.openElements.add(open);
SAXRecorder.this.sequence.addEvent(open);
handleAttributes(atts);
}
/**
* {@inheritDoc}
*/
@Override
public void endElement(String uri, String localName, String qName) {
recordCharacters();
OpenElementEvent open = popLastOpenElement();
open.setWeight(this.currentWeight);
CloseElementEvent close = this.efactory.makeCloseElement(open);
close.setWeight(this.currentWeight);
SAXRecorder.this.sequence.addEvent(close);
// calculate weights
this.currentWeight += popWeight();
}
/**
* {@inheritDoc}
*/
@Override
public void characters(char[] buf, int pos, int len) {
this.ch.append(buf, pos, len);
}
/**
* {@inheritDoc}
*/
@Override
public void ignorableWhitespace(char[] buf1, int pos, int len) {
// this method is only useful if the XML provides a Schema or DTD
// to define in which cases whitespaces can be considered ignorable.
// By default, all white spaces are significant and therefore reported
// by the characters method.
}
/**
* {@inheritDoc}
*/
@Override
public void processingInstruction(String target, String data) {
SAXRecorder.this.sequence.addEvent(new ProcessingInstructionEvent(target, data));
this.currentWeight++;
}
/**
* {@inheritDoc}
*/
@Override
public void endDocument() throws SAXException {
}
/**
* Records the characters which are in the buffer.
*/
private void recordCharacters() {
if (this.ch != null) {
List events = this.tokenizer.tokenize(this.ch);
for (TextEvent e : events) {
SAXRecorder.this.sequence.addEvent(e);
}
this.currentWeight += events.size();
this.ch.setLength(0);
}
}
/**
* Returns the last open element and remove it from the stack.
*
* @return The last open element.
*/
private OpenElementEvent popLastOpenElement() {
return this.openElements.remove(this.openElements.size() - 1);
}
/**
* Returns the last weight and remove it from the stack.
*
* @return The weight on top of the stack.
*/
private int popWeight() {
if (this.weights.size() > 0)
return this.weights.remove(this.weights.size() - 1).intValue();
else
return 0;
}
/**
* Handles the attributes, will add them to the sequence in order if any.
*
* @param atts The attributes to handle.
*/
private void handleAttributes(Attributes atts) {
// only one attribute
if (atts.getLength() == 1) {
SAXRecorder.this.sequence.addEvent(this.efactory.makeAttribute(atts.getURI(0),
atts.getLocalName(0),
atts.getQName(0),
atts.getValue(0)));
// several attributes
} else if (atts.getLength() > 1) {
// store all the attributes
AttributeEvent[] attEvents = new AttributeEvent[atts.getLength()];
for (int i = 0; i < atts.getLength(); i++) {
attEvents[i] = this.efactory.makeAttribute(atts.getURI(i),
atts.getLocalName(i),
atts.getQName(i),
atts.getValue(i));
attEvents[i].setWeight(2);
this.currentWeight += 2;
}
// sort them
Arrays.sort(attEvents, this.comparator);
// add them to the sequence
for (AttributeEvent attEvent : attEvents) {
SAXRecorder.this.sequence.addEvent(attEvent);
}
}
}
}
/**
* A tight error handler that will throw an exception for any error type.
*
* ErrorHandler used only so that namepsace related errors are reported ???
* (they are error type and not fatal error).
*
* @author Jean-baptiste Reure
* @version 17 May 2005
*/
private static final class RecorderErrorHandler implements ErrorHandler {
/**
* {@inheritDoc}
*/
public void error(SAXParseException ex) throws SAXException {
throw ex;
}
/**
* {@inheritDoc}
*/
public void fatalError(SAXParseException ex) throws SAXException {
throw ex;
}
/**
* {@inheritDoc}
*/
public void warning(SAXParseException ex) throws SAXException {
throw ex;
}
}
}