Source code

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 *     https://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.List;
025import java.util.Objects;
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     * SAX Handler to parse a XML properties file.
071     *
072     * @since 1.2
073     */
074    private final class XMLPropertiesHandler extends DefaultHandler {
075
076        /** The key of the current entry being parsed. */
077        private String key;
078
079        /** The value of the current entry being parsed. */
080        private StringBuilder value = new StringBuilder();
081
082        /** Indicates that a comment is being parsed. */
083        private boolean inCommentElement;
084
085        /** Indicates that an entry is being parsed. */
086        private boolean inEntryElement;
087
088        @Override
089        public void characters(final char[] chars, final int start, final int length) {
090
091            /**
092             * We're currently processing an element. All character data from now until the next endElement() call will be the data
093             * for this element.
094             */
095            value.append(chars, start, length);
096        }
097
098        @Override
099        public void endElement(final String uri, final String localName, final String qName) {
100            if (inCommentElement) {
101                // We've just finished a <comment> element so set the header
102                setHeader(value.toString());
103                inCommentElement = false;
104            }
105
106            if (inEntryElement) {
107                // We've just finished an <entry> element, so add the key/value pair
108                addProperty(key, value.toString());
109                inEntryElement = false;
110            }
111
112            // Clear the element value buffer
113            value = new StringBuilder();
114        }
115
116        @Override
117        public void startElement(final String uri, final String localName, final String qName, final Attributes attrs) {
118            if ("comment".equals(qName)) {
119                inCommentElement = true;
120            }
121
122            if ("entry".equals(qName)) {
123                key = attrs.getValue("key");
124                inEntryElement = true;
125            }
126        }
127    }
128
129    /**
130     * The default encoding (UTF-8 as specified by https://docs.oracle.com/javase/8/docs/api/java/util/Properties.html)
131     */
132    public static final String DEFAULT_ENCODING = StandardCharsets.UTF_8.name();
133
134    /**
135     * Default string used when the XML is malformed
136     */
137    private static final String MALFORMED_XML_EXCEPTION = "Malformed XML";
138
139    /** The temporary file locator. */
140    private FileLocator locator;
141
142    /** Stores a header comment. */
143    private String header;
144
145    /**
146     * Creates an empty XMLPropertyConfiguration object which can be used to synthesize a new Properties file by adding
147     * values and then saving(). An object constructed by this constructor cannot be tickled into loading included files because
148     * it cannot supply a base for relative includes.
149     */
150    public XMLPropertiesConfiguration() {
151    }
152
153    /**
154     * Creates and loads the XML properties from the specified DOM node.
155     *
156     * @param element The non-null DOM element.
157     * @throws ConfigurationException Error while loading the Element.
158     * @since 2.0
159     */
160    public XMLPropertiesConfiguration(final Element element) throws ConfigurationException {
161        load(Objects.requireNonNull(element, "element"));
162    }
163
164    /**
165     * Escapes a property value before it is written to disk.
166     *
167     * @param value the value to be escaped
168     * @return the escaped value
169     */
170    private String escapeValue(final Object value) {
171        final String v = StringEscapeUtils.escapeXml10(String.valueOf(value));
172        return String.valueOf(getListDelimiterHandler().escape(v, ListDelimiterHandler.NOOP_TRANSFORMER));
173    }
174
175    /**
176     * Gets the header comment of this configuration.
177     *
178     * @return the header comment
179     */
180    public String getHeader() {
181        return header;
182    }
183
184    /**
185     * Initializes this object with a {@code FileLocator}. The locator is accessed during load and save operations.
186     *
187     * @param locator the associated {@code FileLocator}
188     */
189    @Override
190    public void initFileLocator(final FileLocator locator) {
191        this.locator = locator;
192    }
193
194    /**
195     * Parses a DOM element containing the properties. The DOM element has to follow the XML properties format introduced in
196     * Java, see https://docs.oracle.com/javase/8/docs/api/java/util/Properties.html
197     *
198     * @param element The DOM element
199     * @throws ConfigurationException Error while interpreting the DOM
200     * @since 2.0
201     */
202    public void load(final Element element) throws ConfigurationException {
203        if (!element.getNodeName().equals("properties")) {
204            throw new ConfigurationException(MALFORMED_XML_EXCEPTION);
205        }
206        final NodeList childNodes = element.getChildNodes();
207        for (int i = 0; i < childNodes.getLength(); i++) {
208            final Node item = childNodes.item(i);
209            if (item instanceof Element) {
210                if (item.getNodeName().equals("comment")) {
211                    setHeader(item.getTextContent());
212                } else if (item.getNodeName().equals("entry")) {
213                    final String key = ((Element) item).getAttribute("key");
214                    addProperty(key, item.getTextContent());
215                } else {
216                    throw new ConfigurationException(MALFORMED_XML_EXCEPTION);
217                }
218            }
219        }
220    }
221
222    @Override
223    public void read(final Reader in) throws ConfigurationException {
224        final SAXParserFactory factory = SAXParserFactory.newInstance();
225        factory.setNamespaceAware(false);
226        factory.setValidating(true);
227        try {
228            final SAXParser parser = factory.newSAXParser();
229            final XMLReader xmlReader = parser.getXMLReader();
230            xmlReader.setEntityResolver((publicId, systemId) -> new InputSource(getClass().getClassLoader().getResourceAsStream("properties.dtd")));
231            xmlReader.setContentHandler(new XMLPropertiesHandler());
232            xmlReader.parse(new InputSource(in));
233        } catch (final Exception e) {
234            throw new ConfigurationException("Unable to parse the configuration file", e);
235        }
236        // todo: support included properties ?
237    }
238
239    /**
240     * Writes the configuration as child to the given DOM node
241     *
242     * @param document The DOM document to add the configuration to.
243     * @param parent The DOM parent node.
244     * @since 2.0
245     */
246    public void save(final Document document, final Node parent) {
247        final Element properties = document.createElement("properties");
248        parent.appendChild(properties);
249        if (getHeader() != null) {
250            final Element comment = document.createElement("comment");
251            properties.appendChild(comment);
252            comment.setTextContent(StringEscapeUtils.escapeXml10(getHeader()));
253        }
254        forEach((k, v) -> {
255            if (v instanceof List) {
256                writeProperty(document, properties, k, (List<?>) v);
257            } else {
258                writeProperty(document, properties, k, v);
259            }
260        });
261    }
262
263    /**
264     * Sets the header comment of this configuration.
265     *
266     * @param header the header comment
267     */
268    public void setHeader(final String header) {
269        this.header = header;
270    }
271
272    @Override
273    public void write(final Writer out) throws ConfigurationException {
274        final PrintWriter writer = new PrintWriter(out);
275        String encoding = locator != null ? locator.getEncoding() : null;
276        if (encoding == null) {
277            encoding = DEFAULT_ENCODING;
278        }
279        writer.println("<?xml version=\"1.0\" encoding=\"" + encoding + "\"?>");
280        writer.println("<!DOCTYPE properties SYSTEM \"http://java.sun.com/dtd/properties.dtd\">");
281        writer.println("<properties>");
282        if (getHeader() != null) {
283            writer.println("  <comment>" + StringEscapeUtils.escapeXml10(getHeader()) + "</comment>");
284        }
285        forEach((k, v) -> {
286            if (v instanceof List) {
287                writeProperty(writer, k, (List<?>) v);
288            } else {
289                writeProperty(writer, k, v);
290            }
291        });
292        writer.println("</properties>");
293        writer.flush();
294    }
295
296    private void writeProperty(final Document document, final Node properties, final String key, final List<?> values) {
297        values.forEach(value -> writeProperty(document, properties, key, value));
298    }
299
300    private void writeProperty(final Document document, final Node properties, final String key, final Object value) {
301        final Element entry = document.createElement("entry");
302        properties.appendChild(entry);
303
304        // escape the key
305        final String k = StringEscapeUtils.escapeXml10(key);
306        entry.setAttribute("key", k);
307
308        if (value != null) {
309            final String v = escapeValue(value);
310            entry.setTextContent(v);
311        }
312    }
313
314    /**
315     * Writes a list property.
316     *
317     * @param out the output stream
318     * @param key the key of the property
319     * @param values a list with all property values
320     */
321    private void writeProperty(final PrintWriter out, final String key, final List<?> values) {
322        values.forEach(value -> writeProperty(out, key, value));
323    }
324
325    /**
326     * Writes a property.
327     *
328     * @param out the output stream
329     * @param key the key of the property
330     * @param value the value of the property
331     */
332    private void writeProperty(final PrintWriter out, final String key, final Object value) {
333        // escape the key
334        final String k = StringEscapeUtils.escapeXml10(key);
335
336        if (value != null) {
337            final String v = escapeValue(value);
338            out.println("  <entry key=\"" + k + "\">" + v + "</entry>");
339        } else {
340            out.println("  <entry key=\"" + k + "\"/>");
341        }
342    }
343}