saxbuilder.java

一个用于搜索本地文件内容的小型搜索引擎

                                          boolean coreFeatures)
                                                        throws JDOMException {
        // Set any user-specified features on the parser.
        Iterator iter = features.keySet().iterator();
        while (iter.hasNext()) {
            String  name  = (String)iter.next();
            Boolean value = (Boolean)features.get(name);
            internalSetFeature(parser, name, value.booleanValue(), name);
        }

        // Set any user-specified properties on the parser.
        iter = properties.keySet().iterator();
        while (iter.hasNext()) {
            String name = (String)iter.next();
            internalSetProperty(parser, name, properties.get(name), name);
        }

        if (coreFeatures) {
            // Set validation.
            try {
                internalSetFeature(parser,
                        "http://xml.org/sax/features/validation",
                        validate, "Validation");
            } catch (JDOMException e) {
                // If validation is not supported, and the user is requesting
                // that we don't validate, that's fine - don't throw an
                // exception.
                if (validate)
                    throw e;
            }

            // Setup some namespace features.
            internalSetFeature(parser,
                        "http://xml.org/sax/features/namespaces",
                        true, "Namespaces");
            internalSetFeature(parser,
                        "http://xml.org/sax/features/namespace-prefixes",
                        true, "Namespace prefixes");
        }

        // Set entity expansion
        // Note SAXHandler can work regardless of how this is set, but when
        // entity expansion it's worth it to try to tell the parser not to
        // even bother with external general entities.
        // Apparently no parsers yet support this feature.
        // XXX It might make sense to setEntityResolver() with a resolver
        // that simply ignores external general entities
        try {
            if (parser.getFeature("http://xml.org/sax/features/external-general-entities") != expand) {
                parser.setFeature("http://xml.org/sax/features/external-general-entities", expand);
            }
        }
        catch (SAXNotRecognizedException e) { /* Ignore... */ }
        catch (SAXNotSupportedException  e) { /* Ignore... */ }
    }

    /**
     * Tries to set a feature on the parser. If the feature cannot be set,
     * throws a JDOMException describing the problem.
     */
    private void internalSetFeature(XMLReader parser, String feature,
                    boolean value, String displayName) throws JDOMException {
        try {
            parser.setFeature(feature, value);
        } catch (SAXNotSupportedException e) {
            throw new JDOMException(
                displayName + " feature not supported for SAX driver " + parser.getClass().getName());
        } catch (SAXNotRecognizedException e) {
            throw new JDOMException(
                displayName + " feature not recognized for SAX driver " + parser.getClass().getName());
        }
    }

    /**
     * <p>
     * Tries to set a property on the parser. If the property cannot be set,
     * throws a JDOMException describing the problem.
     * </p>
     */
    private void internalSetProperty(XMLReader parser, String property,
                    Object value, String displayName) throws JDOMException {
        try {
            parser.setProperty(property, value);
        } catch (SAXNotSupportedException e) {
            throw new JDOMException(
                displayName + " property not supported for SAX driver " + parser.getClass().getName());
        } catch (SAXNotRecognizedException e) {
            throw new JDOMException(
                displayName + " property not recognized for SAX driver " + parser.getClass().getName());
        }
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   input stream.
     * </p>
     *
     * @param in <code>InputStream</code> to read from
     * @return <code>Document</code> resultant Document object
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed.
     */
    public Document build(InputStream in)
     throws JDOMException, IOException {
        return build(new InputSource(in));
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   filename.
     * </p>
     *
     * @param file <code>File</code> to read from
     * @return <code>Document</code> resultant Document object
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed
     */
    public Document build(File file)
        throws JDOMException, IOException {
        try {
            URL url = fileToURL(file);
            return build(url);
        } catch (MalformedURLException e) {
            throw new JDOMException("Error in building", e);
        }
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   URL.
     * </p>
     *
     * @param url <code>URL</code> to read from.
     * @return <code>Document</code> - resultant Document object.
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed.
     */
    public Document build(URL url)
        throws JDOMException, IOException {
        String systemID = url.toExternalForm();
        return build(new InputSource(systemID));
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   input stream.
     * </p>
     *
     * @param in <code>InputStream</code> to read from.
     * @param systemId base for resolving relative URIs
     * @return <code>Document</code> resultant Document object
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed
     */
    public Document build(InputStream in, String systemId)
        throws JDOMException, IOException {

        InputSource src = new InputSource(in);
        src.setSystemId(systemId);
        return build(src);
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   Reader.  It's the programmer's responsibility to make sure
     *   the reader matches the encoding of the file.  It's often easier
     *   and safer to use an InputStream rather than a Reader, and to let the
     *   parser auto-detect the encoding from the XML declaration.
     * </p>
     *
     * @param characterStream <code>Reader</code> to read from
     * @return <code>Document</code> resultant Document object
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed
     */
    public Document build(Reader characterStream)
        throws JDOMException, IOException {
        return build(new InputSource(characterStream));
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   Reader.  It's the programmer's responsibility to make sure
     *   the reader matches the encoding of the file.  It's often easier
     *   and safer to use an InputStream rather than a Reader, and to let the
     *   parser auto-detect the encoding from the XML declaration.
     * </p>
     *
     * @param characterStream <code>Reader</code> to read from.
     * @param systemId base for resolving relative URIs
     * @return <code>Document</code> resultant Document object
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed
     */
    public Document build(Reader characterStream, String systemId)
        throws JDOMException, IOException {

        InputSource src = new InputSource(characterStream);
        src.setSystemId(systemId);
        return build(src);
    }

    /**
     * <p>
     * This builds a document from the supplied
     *   URI.
     * </p>
     * @param systemId URI for the input
     * @return <code>Document</code> resultant Document object
     * @throws JDOMException when errors occur in parsing
     * @throws IOException when an I/O error prevents a document
     *         from being fully parsed
     */
    public Document build(String systemId)
        throws JDOMException, IOException {
        return build(new InputSource(systemId));
    }

//    /**
//     * Imitation of File.toURL(), a JDK 1.2 method, reimplemented
//     * here to work with JDK 1.1.
//     *
//     * @see java.io.File
//     *
//     * @param f the file to convert
//     * @return the file path converted to a file: URL
//     */
//    protected URL fileToURL(File f) throws MalformedURLException {
//        String path = f.getAbsolutePath();
//        if (File.separatorChar != '/') {
//            path = path.replace(File.separatorChar, '/');
//        }
//        if (!path.startsWith("/")) {
//            path = "/" + path;
//        }
//        if (!path.endsWith("/") && f.isDirectory()) {
//            path = path + "/";
//        }
//        return new URL("file", "", path);
//    }

    /** Custom File.toUrl() implementation to handle special chars in file names
     *
     * @param file file object whose path will be converted
     * @return URL form of the file, with special characters handled
     * @throws MalformedURLException if there's a problem constructing a URL
     */
    private static URL fileToURL(File file) throws MalformedURLException {
        StringBuffer buffer = new StringBuffer();
        String path = file.getAbsolutePath();

        // Convert non-URL style file separators
        if (File.separatorChar != '/') {
            path = path.replace(File.separatorChar, '/');
        }

        // Make sure it starts at root
        if (!path.startsWith("/")) {
            buffer.append('/');
        }

        // Copy, converting URL special characters as we go
        int len = path.length();
        for (int i = 0; i < len; i++) {
            char c = path.charAt(i);
            if (c == ' ')
                buffer.append("%20");
            else if (c == '#')
                buffer.append("%23");
            else if (c == '%')
                buffer.append("%25");
            else if (c == '&')
                buffer.append("%26");
            else if (c == ';')
                buffer.append("%3B");
            else if (c == '<')
                buffer.append("%3C");
            else if (c == '=')
                buffer.append("%3D");
            else if (c == '>')
                buffer.append("%3E");
            else if (c == '?')
                buffer.append("%3F");
            else if (c == '~')
                buffer.append("%7E");
            else
                buffer.append(c);
        }

        // Make sure directories end with slash
        if (!path.endsWith("/") && file.isDirectory()) {
            buffer.append('/');
        }

        // Return URL
        return new URL("file", "", buffer.toString());
    }

    /**
     * Returns whether or not entities are being expanded into normal text
     * content.
     *
     * @return whether entities are being expanded
     */
    public boolean getExpandEntities() {
        return expand;
    }

    /**
     * <p>
     * This sets whether or not to expand entities for the builder.
     * A true means to expand entities as normal content.  A false means to
     * leave entities unexpanded as <code>EntityRef</code> objects.  The
     * default is true.
     * </p>
     * <p>
     * When this setting is false, the internal DTD subset is retained; when
     * this setting is true, the internal DTD subset is not retained.
     * </p>
     * <p>
     * Note that Xerces (at least up to 1.4.4) has a bug where entities
     * in attribute values will be misreported if this flag is turned off,
     * resulting in entities to appear within element content.  When turning
     * entity expansion off either avoid entities in attribute values, or
     * use another parser like Crimson.
     * http://nagoya.apache.org/bugzilla/show_bug.cgi?id=6111
     * </p>
     *
     * @param expand <code>boolean</code> indicating whether entity expansion
     * should occur.
     */
    public void setExpandEntities(boolean expand) {
        this.expand = expand;
    }
}