saxtreeviewer.java

全面的展示了SAX解析XML文件的强大威力

     * </p>
     *
     * @param prefix <code>String</code> prefix used for the namespace
     *                being reported
     * @param uri <code>String</code> URI for the namespace
     *               being reported
     * @throws <code>SAXException</code> when things go wrong
     */
    public void startPrefixMapping(String prefix, String uri) {
        // No visual events occur here.
        namespaceMappings.put(uri, prefix);
    }

    /**
     * <p>
     *   This indicates the end of a prefix mapping, when the namespace
     *     reported in a <code>{@link #startPrefixMapping}</code> callback
     *     is no longer available.
     * </p>
     *
     * @param prefix <code>String</code> of namespace being reported
     * @throws <code>SAXException</code> when things go wrong
     */
    public void endPrefixMapping(String prefix) {        // No visual events occur here.
        for (Iterator i = namespaceMappings.keySet().iterator(); 
             i.hasNext(); ) {

            String uri = (String)i.next();
            String thisPrefix = (String)namespaceMappings.get(uri);
            if (prefix.equals(thisPrefix)) {
                namespaceMappings.remove(uri);
                break;
            }
        }
    }

    /**
     * <p>
     *   This reports the occurrence of an actual element. It includes
     *     the element's attributes, with the exception of XML vocabulary
     *     specific attributes, such as
     *     <code>xmlns:[namespace prefix]</code> and
     *     <code>xsi:schemaLocation</code>.
     * </p>
     *
     * @param namespaceURI <code>String</code> namespace URI this element
     *               is associated with, or an empty <code>String</code>
     * @param localName <code>String</code> name of element (with no
     *               namespace prefix, if one is present)
     * @param qName <code>String</code> XML 1.0 version of element name:
     *                [namespace prefix]:[localName]
     * @param atts <code>Attributes</code> list for this element
     * @throws <code>SAXException</code> when things go wrong
     */
    public void startElement(String namespaceURI, String localName,
                             String qName, Attributes atts)
        throws SAXException {

        DefaultMutableTreeNode element = 
            new DefaultMutableTreeNode("Element: " + localName);
        current.add(element);
        current = element;

        // Determine namespace
        if (namespaceURI.length() > 0) {
            String prefix = 
                (String)namespaceMappings.get(namespaceURI);
            if (prefix.equals("")) {
                prefix = "[None]";
            }
            DefaultMutableTreeNode namespace =
                new DefaultMutableTreeNode("Namespace: prefix = '" +
                    prefix + "', URI = '" + namespaceURI + "'");
            current.add(namespace);
        }

        // Process attributes
        for (int i=0; i<atts.getLength(); i++) {
            DefaultMutableTreeNode attribute =
                new DefaultMutableTreeNode("Attribute (name = '" +
                                           atts.getLocalName(i) + 
                                           "', value = '" +
                                           atts.getValue(i) + "')");
            String attURI = atts.getURI(i);
            if (attURI.length() > 0) {
                String attPrefix = 
                    (String)namespaceMappings.get(namespaceURI);
                if (attPrefix.equals("")) {
                    attPrefix = "[None]";
                }
                DefaultMutableTreeNode attNamespace =
                    new DefaultMutableTreeNode("Namespace: prefix = '" +
                        attPrefix + "', URI = '" + attURI + "'");
                attribute.add(attNamespace);            
            }
            current.add(attribute);
        }
    }

    /**
     * <p>
     *   Indicates the end of an element
     *     (<code>&lt;/[element name]&gt;</code>) is reached. Note that
     *     the parser does not distinguish between empty
     *     elements and non-empty elements, so this occurs uniformly.
     * </p>
     *
     * @param namespaceURI <code>String</code> URI of namespace this
     *                element is associated with
     * @param localName <code>String</code> name of element without prefix
     * @param qName <code>String</code> name of element in XML 1.0 form
     * @throws <code>SAXException</code> when things go wrong
     */
    public void endElement(String namespaceURI, String localName,
                           String qName)
        throws SAXException {

        // Walk back up the tree
        current = (DefaultMutableTreeNode)current.getParent();
    }

    /**
     * <p>
     *   This reports character data (within an element).
     * </p>
     *
     * @param ch <code>char[]</code> character array with character data
     * @param start <code>int</code> index in array where data starts.
     * @param length <code>int</code> index in array where data ends.
     * @throws <code>SAXException</code> when things go wrong
     */
    public void characters(char[] ch, int start, int length)
        throws SAXException {

        String s = new String(ch, start, length);
        DefaultMutableTreeNode data =
            new DefaultMutableTreeNode("Character Data: '" + s + "'");
        current.add(data);
    }

    /**
     * <p>
     * This reports whitespace that can be ignored in the
     * originating document. This is typically invoked only when
     * validation is ocurring in the parsing process.
     * </p>
     *
     * @param ch <code>char[]</code> character array with character data
     * @param start <code>int</code> index in array where data starts.
     * @param end <code>int</code> index in array where data ends.
     * @throws <code>SAXException</code> when things go wrong
     */
    public void ignorableWhitespace(char[] ch, int start, int length)
        throws SAXException {
        // This is ignorable, so don't display it
    }

    /**
     * <p>
     *   This reports an entity that is skipped by the parser. This
     *     should only occur for non-validating parsers, and then is still
     *     implementation-dependent behavior.
     * </p>
     *
     * @param name <code>String</code> name of entity being skipped
     * @throws <code>SAXException</code> when things go wrong
     */
    public void skippedEntity(String name) throws SAXException {
        DefaultMutableTreeNode skipped =
            new DefaultMutableTreeNode("Skipped Entity: '" + name + "'");
        current.add(skipped);
    }
}

/**
 * <b><code>JTreeErrorHandler</code></b> implements the SAX
 *   <code>ErrorHandler</code> interface and defines callback
 *   behavior for the SAX callbacks associated with an XML
 *   document's warnings and errors.
 */
class JTreeErrorHandler implements ErrorHandler {

    /**
     * <p>
     * This will report a warning that has occurred; this indicates
     *   that while no XML rules were "broken", something appears
     *   to be incorrect or missing.
     * </p>
     *
     * @param exception <code>SAXParseException</code> that occurred.
     * @throws <code>SAXException</code> when things go wrong 
     */
    public void warning(SAXParseException exception)
        throws SAXException {
        System.out.println("**Parsing Warning**\n" +
                           "  Line:    " + 
                              exception.getLineNumber() + "\n" +
                           "  URI:     " + 
                              exception.getSystemId() + "\n" +
                           "  Message: " + 
                              exception.getMessage());        
        throw new SAXException("Warning encountered");
    }

    /**
     * <p>
     * This will report an error that has occurred; this indicates
     *   that a rule was broken, typically in validation, but that
     *   parsing can reasonably continue.
     * </p>
     *
     * @param exception <code>SAXParseException</code> that occurred.
     * @throws <code>SAXException</code> when things go wrong 
     */
    public void error(SAXParseException exception)
        throws SAXException {
        System.out.println("**Parsing Error**\n" +
                           "  Line:    " + 
                              exception.getLineNumber() + "\n" +
                           "  URI:     " + 
                              exception.getSystemId() + "\n" +
                           "  Message: " + 
                              exception.getMessage());
        throw new SAXException("Error encountered");
    }

    /**
     * <p>
     * This will report a fatal error that has occurred; this indicates
     *   that a rule has been broken that makes continued parsing either
     *   impossible or an almost certain waste of time.
     * </p>
     *
     * @param exception <code>SAXParseException</code> that occurred.
     * @throws <code>SAXException</code> when things go wrong 
     */
    public void fatalError(SAXParseException exception)
        throws SAXException {
        System.out.println("**Parsing Fatal Error**\n" +
                           "  Line:    " + 
                              exception.getLineNumber() + "\n" +
                           "  URI:     " + 
                              exception.getSystemId() + "\n" +
                           "  Message: " + 
                              exception.getMessage());        
        throw new SAXException("Fatal Error encountered");
    }
}
//Demo file: book.xml
/*
<?xml version="1.0"?>

<games>
  <game genre="rpg">XML Invaders</game>
  <game genre="rpg">A Node in the XPath</game>
  <game genre="rpg">XPath Racers</game>
</games>

*/