// DOMCatalogReader.java - Read XML Catalog files
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package mf.org.apache.xml.resolver.readers;
import java.util.Hashtable;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.net.MalformedURLException;
import mf.javax.xml.parsers.DocumentBuilderFactory;
import mf.javax.xml.parsers.DocumentBuilder;
import mf.javax.xml.parsers.ParserConfigurationException;
import mf.org.apache.xml.resolver.Catalog;
import mf.org.apache.xml.resolver.CatalogException;
import mf.org.apache.xml.resolver.helpers.Namespaces;
import mf.org.apache.xml.resolver.readers.CatalogReader;
import mf.org.w3c.dom.*;
import org.xml.sax.SAXException;
import mf.org.w3c.dom.Document;
import mf.org.w3c.dom.Element;
import mf.org.w3c.dom.Node;
/**
* A DOM-based CatalogReader.
*
* <p>This class is used to read XML Catalogs using the DOM. This reader
* has an advantage over the SAX-based reader that it can analyze the
* DOM tree rather than simply a series of SAX events. It has the disadvantage
* that it requires all of the code necessary to build and walk a DOM
* 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 DOMCatalogReader 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>
*
* <p>This class requires the <a href="http://java.sun.com/aboutJava/communityprocess/final/jsr005/index.html">Java API for XML Parsing</a>.</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 DOMCatalogReader implements CatalogReader {
/**
* 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();
/**
* Add a new parser to the reader.
*
* <p>This method associates the specified parserClass with the
* namespaceURI/rootElement names specified.</p>
*
* @param namespaceURI The namespace URI. <em>Not</em> the prefix.
* @param rootElement The name of the root element.
* @param parserClass The name of the parserClass to instantiate
* for this kind of catalog.
*/
public void setCatalogParser(String namespaceURI,
String rootElement,
String parserClass) {
if (namespaceURI == null) {
namespaceMap.put(rootElement, parserClass);
} else {
namespaceMap.put("{"+namespaceURI+"}"+rootElement, parserClass);
}
}
/**
* Get the name of the parser class for a given catalog type.
*
* <p>This method returns the parserClass associated with the
* namespaceURI/rootElement names specified.</p>
*
* @param namespaceURI The namespace URI. <em>Not</em> the prefix.
* @param rootElement The name of the root element.
* @return The parser class.
*/
public String getCatalogParser(String namespaceURI,
String rootElement) {
if (namespaceURI == null) {
return (String) namespaceMap.get(rootElement);
} else {
return (String) namespaceMap.get("{"+namespaceURI+"}"+rootElement);
}
}
/**
* Null constructor; something for subclasses to call.
*/
public DOMCatalogReader() { }
/**
* Read a catalog from an input stream.
*
* <p>This class reads a catalog from an input stream:</p>
*
* <ul>
* <li>Based on the QName of the root element, it determines which
* parser to instantiate for this catalog.</li>
* <li>It constructs a DOM Document from the catalog and</li>
* <li>For each child of the root node, it calls the parser's
* parseCatalogEntry method. This method is expected to make
* appropriate calls back into the catalog to add entries for the
* entries in the catalog. It is free to do this in whatever manner
* is appropriate (perhaps using just the node passed in, perhaps
* wandering arbitrarily throughout the tree).</li>
* </ul>
*
* @param catalog The catalog for which this reader is called.
* @param is The input stream that is to be read.
* @throws IOException if the URL cannot be read.
* @throws UnknownCatalogFormatException if the catalog format is
* not recognized.
* @throws UnparseableCatalogException if the catalog cannot be parsed.
* (For example, if it is supposed to be XML and isn't well-formed or
* if the parser class cannot be instantiated.)
*/
public void readCatalog(Catalog catalog, InputStream is)
throws IOException, CatalogException {
DocumentBuilderFactory factory = null;
DocumentBuilder builder = null;
factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(false);
factory.setValidating(false);
try {
builder = factory.newDocumentBuilder();
} catch (ParserConfigurationException pce) {
throw new CatalogException(CatalogException.UNPARSEABLE);
}
Document doc = null;
try {
//MF
doc = (Document) builder.parse(is);
} catch (SAXException se) {
throw new CatalogException(CatalogException.UNKNOWN_FORMAT);
}
Element root = doc.getDocumentElement();
String namespaceURI = Namespaces.getNamespaceURI(root);
String localName = Namespaces.getLocalName(root);
String domParserClass = getCatalogParser(namespaceURI,
localName);
if (domParserClass == null) {
if (namespaceURI == null) {
catalog.getCatalogManager().debug.message(1, "No Catalog parser for "
+ localName);
} else {
catalog.getCatalogManager().debug.message(1, "No Catalog parser for "
+ "{" + namespaceURI + "}"
+ localName);
}
return;
}
DOMCatalogParser domParser = null;
try {
domParser = (DOMCatalogParser) Class.forName(domParserClass).newInstance();
} catch (ClassNotFoundException cnfe) {
catalog.getCatalogManager().debug.message(1, "Cannot load XML Catalog Parser class", domParserClass);
throw new CatalogException(CatalogException.UNPARSEABLE);
} catch (InstantiationException ie) {
catalog.getCatalogManager().debug.message(1, "Cannot instantiate XML Catalog Parser class", domParserClass);
throw new CatalogException(CatalogException.UNPARSEABLE);
} catch (IllegalAccessException iae) {
catalog.getCatalogManager().debug.message(1, "Cannot access XML Catalog Parser class", domParserClass);
throw new CatalogException(CatalogException.UNPARSEABLE);
} catch (ClassCastException cce ) {
catalog.getCatalogManager().debug.message(1, "Cannot cast XML Catalog Parser class", domParserClass);
throw new CatalogException(CatalogException.UNPARSEABLE);
}
Node node = root.getFirstChild();
while (node != null) {
domParser.parseCatalogEntry(catalog, node);
node = node.getNextSibling();
}
}
/**
* Read the catalog behind the specified URL.
*
* @see #readCatalog(Catalog, InputStream)
*
* @param catalog The catalog for which we are reading.
* @param fileUrl The URL of the document that should be read.
*
* @throws MalformedURLException if the specified URL cannot be
* turned into a URL object.
* @throws IOException if the URL cannot be read.
* @throws UnknownCatalogFormatException if the catalog format is
* not recognized.
* @throws UnparseableCatalogException if the catalog cannot be parsed.
* (For example, if it is supposed to be XML and isn't well-formed.)
*/
public void readCatalog(Catalog catalog, String fileUrl)
throws MalformedURLException, IOException, CatalogException {
URL url = new URL(fileUrl);
URLConnection urlCon = url.openConnection();
readCatalog(catalog, urlCon.getInputStream());
}
}