// SAXCatalogReader.java - Read XML Catalog files
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* The Apache Software License, Version 1.1
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package org.apache.xml.resolver.readers;
import java.util.Hashtable;
import java.io.IOException;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.net.MalformedURLException;
import java.net.UnknownHostException;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.parsers.SAXParser;
import org.xml.sax.AttributeList;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.DocumentHandler;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.Parser;
import org.xml.sax.SAXException;
import org.apache.xml.resolver.Catalog;
import org.apache.xml.resolver.CatalogManager;
import org.apache.xml.resolver.CatalogException;
import org.apache.xml.resolver.readers.CatalogReader;
import org.apache.xml.resolver.helpers.Debug;
/**
* A SAX-based CatalogReader.
*
* <p>This class is used to read XML Catalogs using the SAX. This reader
* has an advantage over the DOM-based reader in that it functions on
* the stream of SAX events. It has the disadvantage
* that it cannot look around in the tree.</p>
*
* <p>Since the choice of CatalogReaders (in the InputStream case) can only
* be made on the basis of MIME type, the following problem occurs: only
* one CatalogReader can exist for all XML mime types. In order to get
* around this problem, the SAXCatalogReader relies on a set of external
* CatalogParsers to actually build the catalog.</p>
*
* <p>The selection of CatalogParsers is made on the basis of the QName
* of the root element of the document.</p>
*
* @see Catalog
* @see CatalogReader
* @see SAXCatalogReader
* @see TextCatalogReader
* @see DOMCatalogParser
*
* @author Norman Walsh
* <a href="mailto:Norman.Walsh@Sun.COM">Norman.Walsh@Sun.COM</a>
*
* @version 1.0
*/
public class SAXCatalogReader implements CatalogReader, ContentHandler, DocumentHandler {
/** The SAX Parser Factory */
protected SAXParserFactory parserFactory = null;
/** The SAX Parser Class */
protected String parserClass = null;
/**
* Mapping table from QNames to CatalogParser classes.
*
* <p>Each key in this hash table has the form "elementname"
* or "{namespaceuri}elementname". The former is used if the
* namespace URI is null.</p>
*/
protected Hashtable namespaceMap = new Hashtable();
/** The parser in use for the current catalog. */
private SAXCatalogParser saxParser = null;
/** Set if something goes horribly wrong. It allows the class to
* ignore the rest of the events that are received.
*/
private boolean abandonHope = false;
/** The Catalog that we're working for. */
private Catalog catalog;
/** Set the XML SAX Parser Factory.
*/
public void setParserFactory(SAXParserFactory parserFactory) {
this.parserFactory = parserFactory;
}
/** Set the XML SAX Parser Class
*/
public void setParserClass(String parserClass) {
this.parserClass = parserClass;
}
/** Get the parser factory currently in use. */
public SAXParserFactory getParserFactory() {
return parserFactory;
}
/** Get the parser class currently in use. */
public String getParserClass() {
return parserClass;
}
/** The debug class to use for this reader.
*
* This is a bit of a hack. Anyway, whenever we read for a catalog,
* we extract the debug object
* from the catalog's manager so that we can use it to print messages.
*
* In production, we don't really expect any messages so it doesn't
* really matter. But it's still a bit of a hack.
*/
protected Debug debug = CatalogManager.getStaticManager().debug;
/** The constructor */
public SAXCatalogReader() {
parserFactory = null;
parserClass = null;
}
/** The constructor */
public SAXCatalogReader(SAXParserFactory parserFactory) {
this.parserFactory = parserFactory;
}
/** The constructor */
public SAXCatalogReader(String parserClass) {
this.parserClass = parserClass;
}
/** Set the SAXCatalogParser class for the given namespace/root
* element type.
*/
public void setCatalogParser(String namespaceURI,
String rootElement,
String parserClass) {
if (namespaceURI == null) {
namespaceMap.put(rootElement, parserClass);
} else {
namespaceMap.put("{"+namespaceURI+"}"+rootElement, parserClass);
}
}
/** Get the SAXCatalogParser class for the given namespace/root
* element type.
*/
public String getCatalogParser(String namespaceURI,
String rootElement) {
if (namespaceURI == null) {
return (String) namespaceMap.get(rootElement);
} else {
return (String) namespaceMap.get("{"+namespaceURI+"}"+rootElement);
}
}
/**
* Parse an XML Catalog file.
*
* @param catalog The catalog to which this catalog file belongs
* @param fileUrl The URL or filename of the catalog file to process
*
* @throws MalformedURLException Improper fileUrl
* @throws IOException Error reading catalog file
*/
public void readCatalog(Catalog catalog, String fileUrl)
throws MalformedURLException, IOException,
CatalogException {
URL url = null;
try {
url = new URL(fileUrl);
} catch (MalformedURLException e) {
url = new URL("file:///" + fileUrl);
}
debug = catalog.getCatalogManager().debug;
try {
URLConnection urlCon = url.openConnection();
readCatalog(catalog, urlCon.getInputStream());
} catch (FileNotFoundException e) {
catalog.getCatalogManager().debug.message(1, "Failed to load catalog, file not found",
url.toString());
}
}
/**
* Parse an XML Catalog stream.
*
* @param catalog The catalog to which this catalog file belongs
* @param is The input stream from which the catalog will be read
*
* @throws MalformedURLException Improper fileUrl
* @throws IOException Error reading catalog file
* @throws CatalogException A Catalog exception
*/
public void readCatalog(Catalog catalog, InputStream is)
throws IOException, CatalogException {
// Create an instance of the parser
if (parserFactory == null && parserClass == null) {
debug.message(1, "Cannot read SAX catalog without a parser");
throw new CatalogException(CatalogException.UNPARSEABLE);
}
debug = catalog.getCatalogManager().debug;
EntityResolver bResolver = catalog.getCatalogManager().getBootstrapResolver();
this.catalog = catalog;
try {
if (parserFactory != null) {
SAXParser parser = parserFactory.newSAXParser();
SAXParserHandler spHandler = new SAXParserHandler();
spHandler.setContentHandler(this);
if (bResolver != null) {
spHandler.setEntityResolver(bResolver);
}
parser.parse(new InputSource(is), spHandler);
} else {
Parser parser = (Parser) Class.forName(parserClass).newInstance();
parser.setDocumentHandler(this);
if (bResolver != null) {
parser.setEntityResolver(bResolver);
}
parser.parse(new InputSource(is));
}
} catch (ClassNotFoundException cnfe) {
throw new CatalogException(CatalogException.UNPARSEABLE);
} catch (IllegalAccessException iae) {
throw new CatalogException(CatalogException.UNPARSEABLE);
} catch (InstantiationException ie) {
throw new CatalogException(CatalogException.UNPARSEABLE);
} catch (ParserConfigurationException pce) {
throw new CatalogException(CatalogException.UNKNOWN_FORMAT);
} catch (SAXException se) {
Exception e = se.getException();
// FIXME: there must be a better way
UnknownHostException uhe = new UnknownHostException();
FileNotFoundException fnfe = new FileNotFoundException();
if (e != null) {
if (e.getClass() == uhe.getClass()) {
throw new CatalogException(CatalogException.PARSE_FAILED,
e.toString());
} else if (e.getClass() == fnfe.getClass()) {
throw new CatalogException(CatalogException.PARSE_FAILED,
e.toString());
}
}
throw new CatalogException(se);
}
}
// ----------------------------------------------------------------------
// Implement the SAX ContentHandler interface
/** The SAX <code>setDocumentLocator</code> method. Does nothing. */
public void setDocumentLocator (Locator locator) {
if (saxParser != null) {
saxParser.setDocumentLocator(locator);
}
}
/** The SAX <code>startDocument</code> method. Does nothing. */
public void startDocument () throws SAXException {
saxParser = null;
abandonHope = false;
return;
}
/** The SAX <code>endDocument</code> method. Does nothing. */
public void endDocument ()throws SAXException {
if (saxParser != null) {
saxParser.endDocument();
}
}
/**
* The SAX <code>startElement</code> method.
*
* <p>The catalog parser is selected based on the namespace of the
* first element encountered in the catalog.</p>
*/
public void startElement (String name,
AttributeList atts)
throws SAXException {
if (abandonHope) {
return;
}
if (saxParser == null) {
String prefix = "";
if (name.indexOf(':') > 0) {
prefix = name.substring(0, name.indexOf(':'));
}
String localName = name;
if (localName.indexOf(':') > 0) {
localName = localName.substring(localName.indexOf(':')+1);
}
String namespaceURI = null;
if (prefix.equals("")) {
namespaceURI = atts.getValue("xmlns");
} else {
namespaceURI = atts.getValue("xmlns:" + prefix);
}
String saxParserClass = getCatalogParser(namespaceURI,
localName);
if (saxParserClass == null) {
abandonHope = true;
if (namespaceURI == null) {
debug.message(2, "No Catalog parser for " + name);
} else {
debug.message(2, "No Catalog parser for "
+ "{" + namespaceURI + "}"
+ name);
}
return;
}
try {
saxParser = (SAXCatalogParser)
Class.forName(saxParserClass).newInstance();
saxParser.setCatalog(catalog);
saxParser.startDocument();
saxParser.startElement(name, atts);
} catch (ClassNotFoundException cnfe) {
saxParser = null;
abandonHope = true;
debug.message(2, cnfe.toString());
} catch (InstantiationException ie) {
saxParser = null;
abandonHope = true;
debug.message(2, ie.toString());
} catch (IllegalAccessException iae) {
saxParser = null;
abandonHope = true;
debug.message(2, iae.toString());
} catch (ClassCastException cce ) {
saxParser = null;
abandonHope = true;
debug.message(2, cce.toString());
}
} else {
saxParser.startElement(name, atts);
}
}
/**
* The SAX2 <code>startElement</code> method.
*
* <p>The catalog parser is selected based on the namespace of the
* first element encountered in the catalog.</p>
*/
public void startElement (String namespaceURI,
String localName,
String qName,
Attributes atts)
throws SAXException {
if (abandonHope) {
return;
}
if (saxParser == null) {
String saxParserClass = getCatalogParser(namespaceURI,
localName);
if (saxParserClass == null) {
abandonHope = true;
if (namespaceURI == null) {
debug.message(2, "No Catalog parser for " + localName);
} else {
debug.message(2, "No Catalog parser for "
+ "{" + namespaceURI + "}"
+ localName);
}
return;
}
try {
saxParser = (SAXCatalogParser)
Class.forName(saxParserClass).newInstance();
saxParser.setCatalog(catalog);
saxParser.startDocument();
saxParser.startElement(namespaceURI, localName, qName, atts);
} catch (ClassNotFoundException cnfe) {
saxParser = null;
abandonHope = true;
debug.message(2, cnfe.toString());
} catch (InstantiationException ie) {
saxParser = null;
abandonHope = true;
debug.message(2, ie.toString());
} catch (IllegalAccessException iae) {
saxParser = null;
abandonHope = true;
debug.message(2, iae.toString());
} catch (ClassCastException cce ) {
saxParser = null;
abandonHope = true;
debug.message(2, cce.toString());
}
} else {
saxParser.startElement(namespaceURI, localName, qName, atts);
}
}
/** The SAX <code>endElement</code> method. Does nothing. */
public void endElement (String name) throws SAXException {
if (saxParser != null) {
saxParser.endElement(name);
}
}
/** The SAX2 <code>endElement</code> method. Does nothing. */
public void endElement (String namespaceURI,
String localName,
String qName) throws SAXException {
if (saxParser != null) {
saxParser.endElement(namespaceURI, localName, qName);
}
}
/** The SAX <code>characters</code> method. Does nothing. */
public void characters (char ch[], int start, int length)
throws SAXException {
if (saxParser != null) {
saxParser.characters(ch, start, length);
}
}
/** The SAX <code>ignorableWhitespace</code> method. Does nothing. */
public void ignorableWhitespace (char ch[], int start, int length)
throws SAXException {
if (saxParser != null) {
saxParser.ignorableWhitespace(ch, start, length);
}
}
/** The SAX <code>processingInstruction</code> method. Does nothing. */
public void processingInstruction (String target, String data)
throws SAXException {
if (saxParser != null) {
saxParser.processingInstruction(target, data);
}
}
/** The SAX <code>startPrefixMapping</code> method. Does nothing. */
public void startPrefixMapping (String prefix, String uri)
throws SAXException {
if (saxParser != null) {
saxParser.startPrefixMapping (prefix, uri);
}
}
/** The SAX <code>endPrefixMapping</code> method. Does nothing. */
public void endPrefixMapping (String prefix)
throws SAXException {
if (saxParser != null) {
saxParser.endPrefixMapping (prefix);
}
}
/** The SAX <code>skippedentity</code> method. Does nothing. */
public void skippedEntity (String name)
throws SAXException {
if (saxParser != null) {
saxParser.skippedEntity(name);
}
}
}