    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.configuration2;
    019
    020import java.io.PrintWriter;
    021import java.io.Reader;
    022import java.io.Writer;
    023import java.nio.charset.StandardCharsets;
    024import java.util.Iterator;
    025import java.util.List;
    026
    027import javax.xml.parsers.SAXParser;
    028import javax.xml.parsers.SAXParserFactory;
    029
    030import org.apache.commons.configuration2.convert.ListDelimiterHandler;
    031import org.apache.commons.configuration2.ex.ConfigurationException;
    032import org.apache.commons.configuration2.io.FileLocator;
    033import org.apache.commons.configuration2.io.FileLocatorAware;
    034import org.apache.commons.text.StringEscapeUtils;
    035import org.w3c.dom.Document;
    036import org.w3c.dom.Element;
    037import org.w3c.dom.Node;
    038import org.w3c.dom.NodeList;
    039import org.xml.sax.Attributes;
    040import org.xml.sax.InputSource;
    041import org.xml.sax.XMLReader;
    042import org.xml.sax.helpers.DefaultHandler;
    043
    044/**
    045 * This configuration implements the XML properties format introduced in Java, see
    046 * https://docs.oracle.com/javase/8/docs/api/java/util/Properties.html. An XML properties file looks like this:
    047 *
    048 * <pre>
    049 * &lt;?xml version="1.0"?&gt;
    050 * &lt;!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd"&gt;
    051 * &lt;properties&gt;
    052 *   &lt;comment&gt;Description of the property list&lt;/comment&gt;
    053 *   &lt;entry key="key1"&gt;value1&lt;/entry&gt;
    054 *   &lt;entry key="key2"&gt;value2&lt;/entry&gt;
    055 *   &lt;entry key="key3"&gt;value3&lt;/entry&gt;
    056 * &lt;/properties&gt;
    057 * </pre>
    058 *
    059 * The Java runtime is not required to use this class. The default encoding for this configuration format is UTF-8.
    060 * Note that unlike {@code PropertiesConfiguration}, {@code XMLPropertiesConfiguration} does not support includes.
    061 *
    062 * <em>Note:</em>Configuration objects of this type can be read concurrently by multiple threads. However if one of
    063 * these threads modifies the object, synchronization has to be performed manually.
    064 *
    065 * @since 1.1
    066 */
    067public class XMLPropertiesConfiguration extends BaseConfiguration implements FileBasedConfiguration, FileLocatorAware {
    068
    069    /**
    070     * The default encoding (UTF-8 as specified by https://docs.oracle.com/javase/8/docs/api/java/util/Properties.html)
    071     */
    072    public static final String DEFAULT_ENCODING = StandardCharsets.UTF_8.name();
    073
    074    /**
    075     * Default string used when the XML is malformed
    076     */
    077    private static final String MALFORMED_XML_EXCEPTION = "Malformed XML";
    078
    079    /** The temporary file locator. */
    080    private FileLocator locator;
    081
    082    /** Stores a header comment. */
    083    private String header;
    084
    085    /**
    086     * Creates an empty XMLPropertyConfiguration object which can be used to synthesize a new Properties file by adding
    087     * values and then saving(). An object constructed by this C'tor can not be tickled into loading included files because
    088     * it cannot supply a base for relative includes.
    089     */
    090    public XMLPropertiesConfiguration() {
    091    }
    092
    093    /**
    094     * Creates and loads the xml properties from the specified DOM node.
    095     *
    096     * @param element The DOM element
    097     * @throws ConfigurationException Error while loading the properties file
    098     * @since 2.0
    099     */
    100    public XMLPropertiesConfiguration(final Element element) throws ConfigurationException {
    101        this.load(element);
    102    }
    103
    104    /**
    105     * Gets the header comment of this configuration.
    106     *
    107     * @return the header comment
    108     */
    109    public String getHeader() {
    110        return header;
    111    }
    112
    113    /**
    114     * Sets the header comment of this configuration.
    115     *
    116     * @param header the header comment
    117     */
    118    public void setHeader(final String header) {
    119        this.header = header;
    120    }
    121
    122    @Override
    123    public void read(final Reader in) throws ConfigurationException {
    124        final SAXParserFactory factory = SAXParserFactory.newInstance();
    125        factory.setNamespaceAware(false);
    126        factory.setValidating(true);
    127
    128        try {
    129            final SAXParser parser = factory.newSAXParser();
    130
    131            final XMLReader xmlReader = parser.getXMLReader();
    132            xmlReader.setEntityResolver((publicId, systemId) -> new InputSource(getClass().getClassLoader().getResourceAsStream("properties.dtd")));
    133            xmlReader.setContentHandler(new XMLPropertiesHandler());
    134            xmlReader.parse(new InputSource(in));
    135        } catch (final Exception e) {
    136            throw new ConfigurationException("Unable to parse the configuration file", e);
    137        }
    138
    139        // todo: support included properties ?
    140    }
    141
    142    /**
    143     * Parses a DOM element containing the properties. The DOM element has to follow the XML properties format introduced in
    144     * Java, see https://docs.oracle.com/javase/8/docs/api/java/util/Properties.html
    145     *
    146     * @param element The DOM element
    147     * @throws ConfigurationException Error while interpreting the DOM
    148     * @since 2.0
    149     */
    150    public void load(final Element element) throws ConfigurationException {
    151        if (!element.getNodeName().equals("properties")) {
    152            throw new ConfigurationException(MALFORMED_XML_EXCEPTION);
    153        }
    154        final NodeList childNodes = element.getChildNodes();
    155        for (int i = 0; i < childNodes.getLength(); i++) {
    156            final Node item = childNodes.item(i);
    157            if (item instanceof Element) {
    158                if (item.getNodeName().equals("comment")) {
    159                    setHeader(item.getTextContent());
    160                } else if (item.getNodeName().equals("entry")) {
    161                    final String key = ((Element) item).getAttribute("key");
    162                    addProperty(key, item.getTextContent());
    163                } else {
    164                    throw new ConfigurationException(MALFORMED_XML_EXCEPTION);
    165                }
    166            }
    167        }
    168    }
    169
    170    @Override
    171    public void write(final Writer out) throws ConfigurationException {
    172        final PrintWriter writer = new PrintWriter(out);
    173
    174        String encoding = locator != null ? locator.getEncoding() : null;
    175        if (encoding == null) {
    176            encoding = DEFAULT_ENCODING;
    177        }
    178        writer.println("<?xml version=\"1.0\" encoding=\"" + encoding + "\"?>");
    179        writer.println("<!DOCTYPE properties SYSTEM \"http://java.sun.com/dtd/properties.dtd\">");
    180        writer.println("<properties>");
    181
    182        if (getHeader() != null) {
    183            writer.println("  <comment>" + StringEscapeUtils.escapeXml10(getHeader()) + "</comment>");
    184        }
    185
    186        final Iterator<String> keys = getKeys();
    187        while (keys.hasNext()) {
    188            final String key = keys.next();
    189            final Object value = getProperty(key);
    190
    191            if (value instanceof List) {
    192                writeProperty(writer, key, (List<?>) value);
    193            } else {
    194                writeProperty(writer, key, value);
    195            }
    196        }
    197
    198        writer.println("</properties>");
    199        writer.flush();
    200    }
    201
    202    /**
    203     * Write a property.
    204     *
    205     * @param out the output stream
    206     * @param key the key of the property
    207     * @param value the value of the property
    208     */
    209    private void writeProperty(final PrintWriter out, final String key, final Object value) {
    210        // escape the key
    211        final String k = StringEscapeUtils.escapeXml10(key);
    212
    213        if (value != null) {
    214            final String v = escapeValue(value);
    215            out.println("  <entry key=\"" + k + "\">" + v + "</entry>");
    216        } else {
    217            out.println("  <entry key=\"" + k + "\"/>");
    218        }
    219    }
    220
    221    /**
    222     * Write a list property.
    223     *
    224     * @param out the output stream
    225     * @param key the key of the property
    226     * @param values a list with all property values
    227     */
    228    private void writeProperty(final PrintWriter out, final String key, final List<?> values) {
    229        values.forEach(value -> writeProperty(out, key, value));
    230    }
    231
    232    /**
    233     * Writes the configuration as child to the given DOM node
    234     *
    235     * @param document The DOM document to add the configuration to
    236     * @param parent The DOM parent node
    237     * @since 2.0
    238     */
    239    public void save(final Document document, final Node parent) {
    240        final Element properties = document.createElement("properties");
    241        parent.appendChild(properties);
    242        if (getHeader() != null) {
    243            final Element comment = document.createElement("comment");
    244            properties.appendChild(comment);
    245            comment.setTextContent(StringEscapeUtils.escapeXml10(getHeader()));
    246        }
    247
    248        final Iterator<String> keys = getKeys();
    249        while (keys.hasNext()) {
    250            final String key = keys.next();
    251            final Object value = getProperty(key);
    252
    253            if (value instanceof List) {
    254                writeProperty(document, properties, key, (List<?>) value);
    255            } else {
    256                writeProperty(document, properties, key, value);
    257            }
    258        }
    259    }
    260
    261    /**
    262     * Initializes this object with a {@code FileLocator}. The locator is accessed during load and save operations.
    263     *
    264     * @param locator the associated {@code FileLocator}
    265     */
    266    @Override
    267    public void initFileLocator(final FileLocator locator) {
    268        this.locator = locator;
    269    }
    270
    271    private void writeProperty(final Document document, final Node properties, final String key, final Object value) {
    272        final Element entry = document.createElement("entry");
    273        properties.appendChild(entry);
    274
    275        // escape the key
    276        final String k = StringEscapeUtils.escapeXml10(key);
    277        entry.setAttribute("key", k);
    278
    279        if (value != null) {
    280            final String v = escapeValue(value);
    281            entry.setTextContent(v);
    282        }
    283    }
    284
    285    private void writeProperty(final Document document, final Node properties, final String key, final List<?> values) {
    286        values.forEach(value -> writeProperty(document, properties, key, value));
    287    }
    288
    289    /**
    290     * Escapes a property value before it is written to disk.
    291     *
    292     * @param value the value to be escaped
    293     * @return the escaped value
    294     */
    295    private String escapeValue(final Object value) {
    296        final String v = StringEscapeUtils.escapeXml10(String.valueOf(value));
    297        return String.valueOf(getListDelimiterHandler().escape(v, ListDelimiterHandler.NOOP_TRANSFORMER));
    298    }
    299
    300    /**
    301     * SAX Handler to parse a XML properties file.
    302     *
    303     * @since 1.2
    304     */
    305    private final class XMLPropertiesHandler extends DefaultHandler {
    306        /** The key of the current entry being parsed. */
    307        private String key;
    308
    309        /** The value of the current entry being parsed. */
    310        private StringBuilder value = new StringBuilder();
    311
    312        /** Indicates that a comment is being parsed. */
    313        private boolean inCommentElement;
    314
    315        /** Indicates that an entry is being parsed. */
    316        private boolean inEntryElement;
    317
    318        @Override
    319        public void startElement(final String uri, final String localName, final String qName, final Attributes attrs) {
    320            if ("comment".equals(qName)) {
    321                inCommentElement = true;
    322            }
    323
    324            if ("entry".equals(qName)) {
    325                key = attrs.getValue("key");
    326                inEntryElement = true;
    327            }
    328        }
    329
    330        @Override
    331        public void endElement(final String uri, final String localName, final String qName) {
    332            if (inCommentElement) {
    333                // We've just finished a <comment> element so set the header
    334                setHeader(value.toString());
    335                inCommentElement = false;
    336            }
    337
    338            if (inEntryElement) {
    339                // We've just finished an <entry> element, so add the key/value pair
    340                addProperty(key, value.toString());
    341                inEntryElement = false;
    342            }
    343
    344            // Clear the element value buffer
    345            value = new StringBuilder();
    346        }
    347
    348        @Override
    349        public void characters(final char[] chars, final int start, final int length) {
    350            /**
    351             * We're currently processing an element. All character data from now until the next endElement() call will be the data
    352             * for this element.
    353             */
    354            value.append(chars, start, length);
    355        }
    356    }
    357}