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// XMLCatalogReader.java - Read XML Catalog files
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// Written by Norman Walsh, nwalsh@arbortext.com
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// NO WARRANTY! This class is in the public domain.
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package com.arbortext.catalog;
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import java.lang.Integer;
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import java.util.Vector;
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import java.util.Enumeration;
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import java.io.IOException;
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import java.net.URL;
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import java.net.MalformedURLException;
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import com.arbortext.catalog.CatalogEntry;
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import com.arbortext.catalog.CatalogReader;
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import com.arbortext.catalog.InvalidCatalogEntryTypeException;
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import com.arbortext.catalog.InvalidCatalogEntryException;
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import com.arbortext.catalog.UnknownCatalogFormatException;
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import com.arbortext.catalog.NotXMLCatalogException;
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import com.arbortext.catalog.NoXMLParserException;
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import org.xml.sax.*;
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/**
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* <p>Parses XML Catalog files.</p>
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*
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* <blockquote>
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* <em>This module, both source code and documentation, is in the
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* Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
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* </blockquote>
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*
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* <p>This class reads XML Catalog files, returning a stream
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* of tokens. At present, it recognizes John Cowan's
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* <a href="http://www.ccil.org/~cowan/XML/XCatalog.html">XML Catalogs</a>
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* (formerly XCatalogs). In the future, additional XML Catalog formats
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* may be supported.</p>
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*
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* <p>This code interrogates the following non-standard system properties:</p>
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*
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* <dl>
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* <dt><b>xml.catalog.debug</b></dt>
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* <dd><p>Sets the debug level. A value of 0 is assumed if the
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* property is not set or is not a number.</p></dd>
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* </dl>
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*
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* @see Catalog
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*
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* @author Arbortext, Inc.
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* @author Norman Walsh
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* <a href="mailto:nwalsh@arbortext.com">nwalsh@arbortext.com</a>
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* @version 1.0
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*/
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public class XMLCatalogReader implements DocumentHandler {
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// These are class variables so that several methods can access them
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/** The filename (URL) of the catalog being read */
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private String catfilename = null;
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/**
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* <p>The debug level</p>
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*
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* <p>In general, higher numbers produce more information:</p>
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* <ul>
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* <li>0, no messages
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* <li>1, minimal messages (high-level status)
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* <li>2, detailed messages
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* </ul>
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*/
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public int debug = 0;
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/**
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* Indicates that the catalog type is not XML
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*/
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private static final int NOTXMLCATALOG = -1;
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/**
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* Indicates that the catalog type is unknown.
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*/
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private static final int UNKNOWNCATALOG = 0;
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/**
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* Indicates that the catalog type is an XML Catalog (John Cowan's
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* XCatalog)
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*/
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private static final int XCATALOG = 1;
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/**
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* Indicates the catalog type.
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*/
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private int catalogType = NOTXMLCATALOG;
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/**
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* <p>The list of entries scanned from the catalog.</p>
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*
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* <p>The SAX Parser is event-driven, but the Catalog class expects
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* to iterate through the entries with
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* <a href="#nextToken()">nextToken()</a>. So this class builds a
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* vector of entries during the parse and returns them sequentially
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* when <a href="#nextToken()">nextToken()</a> is called.</p>
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*
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* @see Catalog
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*/
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private Vector catalogEntries = new Vector();
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/**
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* An enumerator for walking through the list of catalogEntries.
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*/
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private Enumeration catalogEnum = null;
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/**
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* <p>The name of the parser class to load when parsing XML Catalogs.</p>
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*
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* <p>If a parser class is provided,
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* subsequent attempts to parse Catalog files will begin
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* by attemptiing an XML parse of the catalog file using a parser
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* of this class.
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* If the XML parse fails, the "default" text parse will be done
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* instead.</p>
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*/
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private String parserClass = null;
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/**
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* <p>Construct an XMLCatalogReader object.</p>
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*/
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public XMLCatalogReader() {
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String property = System.getProperty("xml.catalog.debug");
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if (property != null) {
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try {
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debug = Integer.parseInt(property);
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} catch (NumberFormatException e) {
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debug = 0;
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}
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}
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}
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/**
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* <p>Sets the parser class, enabling XML Catalog parsing.</p>
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*
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* <p>Sets the parser class that will be used for loading XML Catalogs.
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* If this method is not called, all attempts to use the
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* <code>XMLCatalogParser</code> will fail, throwing a
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* <code>NoXMLParserException</code>.</p>
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*
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* @param parser The name of a class implementing the SAX Parser
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* interface to be used for subsequent XML Catalog parsing.
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*
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* @see com.arbortext.catalog.NoXMLParserException
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*/
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public void setParserClass(String parser) {
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parserClass = parser;
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}
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/**
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* <p>Attempt to parse an XML Catalog file.</p>
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*
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* @param fileUrl The URL or filename of the catalog file to process
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* @param catParser A SAX-compliant parser to use for reading the files
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*
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* @throws SAXException Error parsing catalog file.
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* @throws IOException Error reading catalog file.
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* @throws NoXMLParserException No Parser class provided.
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* @throws NotXMLCatalogException The Catalog appears not to be XML.
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* @throws UnknownCatalogFormatException Unexpected XML catalog type.
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* @throws ClassNotFoundException Parser class can't be found.
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* @throws InstantiationException Parser class can't be instantiated.
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* @throws IllegalAccessException Error instantiating parser class.
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* @throws ClassCastException Parser class isn't a SAX Parser.
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*/
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public void parseCatalog(String fileUrl)
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throws SAXException, IOException,
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NotXMLCatalogException, NoXMLParserException,
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UnknownCatalogFormatException, ClassNotFoundException,
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InstantiationException, IllegalAccessException,
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ClassCastException {
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// Create an instance of the parser
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if (parserClass == null) {
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throw new NoXMLParserException();
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}
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Parser parser = (Parser) Class.forName(parserClass).newInstance();
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catfilename = fileUrl;
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parser.setDocumentHandler(this);
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parser.parse(fileUrl);
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if (catalogType == NOTXMLCATALOG) {
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// Why doesn't the attempt to parse this file throw a
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// SAX Exception???
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throw new NotXMLCatalogException();
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}
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if (catalogType == UNKNOWNCATALOG) {
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throw new UnknownCatalogFormatException();
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}
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}
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/**
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* <p>Get the next entry from the file</p>
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*
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* @throws IOException Error reading catalog file
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* @return A CatalogEntry object for the next entry in the catalog
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*/
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public CatalogEntry nextEntry() throws IOException {
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if (catalogEnum == null) {
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catalogEnum = catalogEntries.elements();
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}
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if (catalogEnum.hasMoreElements()) {
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return (CatalogEntry) catalogEnum.nextElement();
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} else {
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return null;
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}
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}
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// ----------------------------------------------------------------------
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/*
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* <p>Parse elements from John Cowan's XML Catalog doctype.</p>
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*
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* <p>Each recognized element is turned into an appropriate
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* CatalogEntry and put onto the entries vector for later
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* retrieval.</p>
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*
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* @param name The name of the element.
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* @param atts The list of attributes on the element.
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*
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* @see CatalogEntry
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*/
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private void xCatalogEntry (String name, AttributeList atts) {
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CatalogEntry ce = null;
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try {
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if (name.equals("Base")) {
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ce = new CatalogEntry(CatalogEntry.BASE,
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atts.getValue("HRef"));
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debug(3, "Base", atts.getValue("HRef"));
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}
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if (name.equals("Delegate")) {
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ce = new CatalogEntry(CatalogEntry.DELEGATE,
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CatalogReader.normalize(atts.getValue("PublicId")),
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atts.getValue("HRef"));
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debug(3, "Delegate",
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CatalogReader.normalize(atts.getValue("PublicId")),
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atts.getValue("HRef"));
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}
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if (name.equals("Extend")) {
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ce = new CatalogEntry(CatalogEntry.CATALOG,
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atts.getValue("HRef"));
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debug(3, "Extend", atts.getValue("HRef"));
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}
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if (name.equals("Map")) {
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ce = new CatalogEntry(CatalogEntry.PUBLIC,
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CatalogReader.normalize(atts.getValue("PublicId")),
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atts.getValue("HRef"));
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debug(3, "Map",
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CatalogReader.normalize(atts.getValue("PublicId")),
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atts.getValue("HRef"));
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}
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if (name.equals("Remap")) {
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ce = new CatalogEntry(CatalogEntry.SYSTEM,
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atts.getValue("SystemId"),
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atts.getValue("HRef"));
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debug(3, "Remap",
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CatalogReader.normalize(atts.getValue("SystemId")),
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atts.getValue("HRef"));
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}
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if (ce == null) {
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// This is equivalent to an invalid catalog entry type
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debug(1, "Invalid catalog entry type", name);
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}
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} catch (InvalidCatalogEntryTypeException icete) {
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debug(1, "Invalid catalog entry type", name);
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} catch (InvalidCatalogEntryException icete) {
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debug(1, "Invalid catalog entry", name);
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}
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if (ce != null) {
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catalogEntries.addElement(ce);
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}
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}
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// ----------------------------------------------------------------------
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// Implement the SAX DocumentHandler interface
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/** <p>The SAX <code>setDocumentLocator</code> method. Does nothing.</p> */
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public void setDocumentLocator (Locator locator) {
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return;
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}
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/** <p>The SAX <code>startDocument</code> method. Does nothing.</p> */
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public void startDocument ()
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throws SAXException {
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return;
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}
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/** <p>The SAX <code>endDocument</code> method. Does nothing.</p> */
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public void endDocument ()
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throws SAXException {
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return;
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}
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/**
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* <p>The SAX <code>startElement</code> method.</p>
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*
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* <p>This element attempts to identify the type of catalog
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* by looking at the name of the first element encountered.
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* If it recognizes the element, it sets the <code>catalogType</code>
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* appropriately.</p>
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*
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* <p>After the catalog type has been identified, the appropriate
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* entry parser is called for each subsequent element in the
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* catalog.</p>
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*
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* @param name The name of the element.
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* @param atts The list of attributes on the element.
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*
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*/
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public void startElement (String name, AttributeList atts)
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throws SAXException {
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if (catalogType == UNKNOWNCATALOG || catalogType == NOTXMLCATALOG) {
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if (name.equals("XMLCatalog")) {
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catalogType = XCATALOG;
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return;
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}
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}
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331
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if (catalogType == XCATALOG) {
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xCatalogEntry(name, atts);
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}
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}
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336
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/** <p>The SAX <code>endElement</code> method. Does nothing.</p> */
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public void endElement (String name)
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throws SAXException {
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return;
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}
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342
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343
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/** <p>The SAX <code>characters</code> method. Does nothing.</p> */
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public void characters (char ch[], int start, int length)
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throws SAXException {
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return;
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}
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/** <p>The SAX <code>ignorableWhitespace</code> method. Does nothing.</p> */
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public void ignorableWhitespace (char ch[], int start, int length)
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throws SAXException {
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return;
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}
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/** <p>The SAX <code>processingInstruction</code> method. Does nothing.</p> */
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public void processingInstruction (String target, String data)
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throws SAXException {
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return;
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}
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360
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// -----------------------------------------------------------------
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/**
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* <p>Print debug message (if the debug level is high enough).</p>
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*
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* @param level The debug level of this message. This message
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* will only be
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* displayed if the current debug level is at least equal to this
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* value.
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* @param message The text of the message.
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* @param token The catalog file token being processed.
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*/
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private void debug(int level, String message, String token) {
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if (debug >= level) {
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System.out.println(message + ": " + token);
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}
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}
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378
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/**
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* <p>Print debug message (if the debug level is high enough).</p>
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381
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*
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382
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* @param level The debug level of this message. This message
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383
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* will only be
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384
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* displayed if the current debug level is at least equal to this
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385
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* value.
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* @param message The text of the message.
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* @param token The catalog file token being processed.
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* @param spec The argument to the token.
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*/
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390
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private void debug(int level, String message, String token, String spec) {
|
|
391
|
if (debug >= level) {
|
|
392
|
System.out.println(message + ": " + token + " " + spec);
|
|
393
|
}
|
|
394
|
}
|
|
395
|
|
|
396
|
/**
|
|
397
|
* <p>Print debug message (if the debug level is high enough).</p>
|
|
398
|
*
|
|
399
|
* @param level The debug level of this message. This message
|
|
400
|
* will only be
|
|
401
|
* displayed if the current debug level is at least equal to this
|
|
402
|
* value.
|
|
403
|
* @param message The text of the message.
|
|
404
|
* @param token The catalog file token being processed.
|
|
405
|
* @param spec1 The first argument to the token.
|
|
406
|
* @param spec2 The second argument to the token.
|
|
407
|
*/
|
|
408
|
private void debug(int level, String message,
|
|
409
|
String token, String spec1, String spec2) {
|
|
410
|
if (debug >= level) {
|
|
411
|
System.out.println(message + ": " + token + " " + spec1);
|
|
412
|
System.out.println("\t" + spec2);
|
|
413
|
}
|
|
414
|
}
|
|
415
|
}
|