Mercurial > dive4elements > framework

comparison artifacts-common/src/main/java/de/intevation/artifacts/common/utils/XMLUtils.java @ 102:4122dbc9711b

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Added a new package artifacts-common for classes and utilities used in several packages. artifacts/trunk@1285 c6561f87-3c4e-4783-a992-168aeb5c3f6f
author Ingo Weinzierl <ingo.weinzierl@intevation.de>
date Wed, 02 Feb 2011 14:37:28 +0000
parents
children 1282cf96d3eb
comparison
equal deleted inserted replaced
101:7fc0650f194c 102:4122dbc9711b
1 /*
2 * Copyright (c) 2010 by Intevation GmbH
3 *
4 * This program is free software under the LGPL (>=v2.1)
5 * Read the file LGPL.txt coming with the software for details
6 * or visit http://www.gnu.org/licenses/ if it does not exist.
7 */
8
9 package de.intevation.artifactdatabase;
10
11 import java.io.File;
12 import java.io.IOException;
13 import java.io.OutputStream;
14
15 import javax.xml.namespace.NamespaceContext;
16 import javax.xml.namespace.QName;
17
18 import javax.xml.parsers.DocumentBuilderFactory;
19 import javax.xml.parsers.ParserConfigurationException;
20
21 import javax.xml.transform.Transformer;
22 import javax.xml.transform.TransformerConfigurationException;
23 import javax.xml.transform.TransformerException;
24 import javax.xml.transform.TransformerFactory;
25 import javax.xml.transform.TransformerFactoryConfigurationError;
26
27 import javax.xml.transform.dom.DOMSource;
28
29 import javax.xml.transform.stream.StreamResult;
30
31 import javax.xml.xpath.XPath;
32 import javax.xml.xpath.XPathConstants;
33 import javax.xml.xpath.XPathExpressionException;
34 import javax.xml.xpath.XPathFactory;
35
36 import org.apache.log4j.Logger;
37
38 import org.w3c.dom.Attr;
39 import org.w3c.dom.Document;
40 import org.w3c.dom.Element;
41
42 import org.xml.sax.SAXException;
43
44 /**
45 * Some helper functions to ease work with XML concering namespaces, XPATH
46 * and so on.
47 * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a>
48 */
49 public final class XMLUtils
50 {
51 /**
52 * W3C URL of XForms
53 */
54 public static final String XFORM_URL = "http://www.w3.org/2002/xforms";
55 /**
56 * W3C prefix of XForms
57 */
58 public static final String XFORM_PREFIX = "xform";
59
60 private static Logger logger = Logger.getLogger(XMLUtils.class);
61
62 private XMLUtils() {
63 }
64
65 /**
66 * Helper class to generate elements and attributes with
67 * namespaces.
68 */
69 public static class ElementCreator
70 {
71 /**
72 * owner document of the elements to be created
73 */
74 protected Document document;
75 /**
76 * namespace to be used
77 */
78 protected String ns;
79 /**
80 * prefix to be used
81 */
82 protected String prefix;
83
84 /**
85 * Constructor to create an element/attribute creator
86 * with a given namespace and namespace prefix using a
87 * given owner document.
88 * @param document The owning document
89 * @param ns The namespace
90 * @param prefix The namespace prefix
91 */
92 public ElementCreator(Document document, String ns, String prefix) {
93 this.document = document;
94 this.ns = ns;
95 this.prefix = prefix;
96 }
97
98 /**
99 * Creates a new element using the owning document with
100 * the this creators namespace and namespace prefix.
101 * @param name The name of the element
102 * @return The new element
103 */
104 public Element create(String name) {
105 Element element = document.createElementNS(ns, name);
106 element.setPrefix(prefix);
107 return element;
108 }
109
110 /**
111 * Adds a new attribute and its value to a given element.
112 * It does not set the namespace prefix.
113 * @param element The element to add the attribute to
114 * @param name The name of the attribute
115 * @param value The value of the attribute
116 */
117 public void addAttr(Element element, String name, String value) {
118 addAttr(element, name, value, false);
119 }
120
121 /**
122 * Adds a new attribute and its value to a given element.
123 * If the namespace prefix is used is decided by the 'addPrefix' flag.
124 * @param element The element to add the attribute to
125 * @param name The name of the attribute
126 * @param value The value of the attribute
127 * @param addPrefix If true the creators namespace prefix is
128 * set on the attribute.
129 */
130 public void addAttr(
131 Element element,
132 String name,
133 String value,
134 boolean addPrefix
135 ) {
136 Attr attr = document.createAttributeNS(ns, name);
137 attr.setValue(value);
138
139 if (addPrefix)
140 attr.setPrefix(prefix);
141
142 element.setAttributeNode(attr);
143 }
144 } // class ElementCreator
145
146 /**
147 * Creates a new XML document
148 * @return the new XML document ot null if something went wrong during
149 * creation.
150 */
151 public static final Document newDocument() {
152 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
153 factory.setNamespaceAware(true);
154
155 try {
156 return factory.newDocumentBuilder().newDocument();
157 }
158 catch (ParserConfigurationException pce) {
159 logger.error(pce.getLocalizedMessage(), pce);
160 }
161 return null;
162 }
163
164 /**
165 * Loads a XML document namespace aware from a file
166 * @param file The file to load.
167 * @return the XML document or null if something went wrong
168 * during loading.
169 */
170 public static final Document parseDocument(File file) {
171 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
172 factory.setNamespaceAware(true);
173
174 try {
175 return factory.newDocumentBuilder().parse(file);
176 }
177 catch (ParserConfigurationException pce) {
178 logger.error(pce.getLocalizedMessage(), pce);
179 }
180 catch (SAXException se) {
181 logger.error(se.getLocalizedMessage(), se);
182 }
183 catch (IOException ioe) {
184 logger.error(ioe.getLocalizedMessage(), ioe);
185 }
186 return null;
187 }
188
189 /**
190 * Creates a new XPath without a namespace context.
191 * @return the new XPath.
192 */
193 public static final XPath newXPath() {
194 return newXPath(null);
195 }
196
197 /**
198 * Creates a new XPath with a given namespace context.
199 * @param namespaceContext The namespace context to be used or null
200 * if none should be used.
201 * @return The new XPath
202 */
203 public static final XPath newXPath(NamespaceContext namespaceContext) {
204 XPathFactory factory = XPathFactory.newInstance();
205 XPath xpath = factory.newXPath();
206 if (namespaceContext != null) {
207 xpath.setNamespaceContext(namespaceContext);
208 }
209 return xpath;
210 }
211
212 /**
213 * Evaluates an XPath query on a given object and returns the result
214 * as a given type. No namespace context is used.
215 * @param root The object which is used as the root of the tree to
216 * be searched in.
217 * @param query The XPath query
218 * @param returnTyp The type of the result.
219 * @return The result of type 'returnTyp' or null if something
220 * went wrong during XPath evaluation.
221 */
222 public static final Object xpath(
223 Object root,
224 String query,
225 QName returnTyp
226 ) {
227 return xpath(root, query, returnTyp, null);
228 }
229
230 /**
231 * Evaluates an XPath query on a given object and returns the result
232 * as a string. A given namespace context is used.
233 * @param root The object which is used as the root of the tree to
234 * be searched in.
235 * @param query The XPath query
236 * @param namespaceContext The namespace context to be used or null
237 * if none should be used.
238 * @return The result of the query or null if something went wrong
239 * during XPath evaluation.
240 */
241 public static final String xpathString(
242 Object root, String query, NamespaceContext namespaceContext
243 ) {
244 return (String)xpath(
245 root, query, XPathConstants.STRING, namespaceContext);
246 }
247
248 /**
249 * Evaluates an XPath query on a given object and returns the result
250 * as a given type. Optionally a namespace context is used.
251 * @param root The object which is used as the root of the tree to
252 * be searched in.
253 * @param query The XPath query
254 * @param returnType The type of the result.
255 * @param namespaceContext The namespace context to be used or null
256 * if none should be used.
257 * @return The result of type 'returnTyp' or null if something
258 * went wrong during XPath evaluation.
259 */
260 public static final Object xpath(
261 Object root,
262 String query,
263 QName returnType,
264 NamespaceContext namespaceContext
265 ) {
266 if (root == null) {
267 return null;
268 }
269
270 try {
271 XPath xpath = newXPath(namespaceContext);
272 if (xpath != null) {
273 return xpath.evaluate(query, root, returnType);
274 }
275 }
276 catch (XPathExpressionException xpee) {
277 logger.error(xpee.getLocalizedMessage(), xpee);
278 }
279
280 return null;
281 }
282
283 /**
284 * Streams out an XML document to a given output stream.
285 * @param document The document to be streamed out.
286 * @param out The output stream to be used.
287 * @return true if operation succeeded else false.
288 */
289 public static boolean toStream(Document document, OutputStream out) {
290 try {
291 Transformer transformer =
292 TransformerFactory.newInstance().newTransformer();
293 DOMSource source = new DOMSource(document);
294 StreamResult result = new StreamResult(out);
295 transformer.transform(source, result);
296 return true;
297 }
298 catch (TransformerConfigurationException tce) {
299 logger.error(tce.getLocalizedMessage(), tce);
300 }
301 catch (TransformerFactoryConfigurationError tfce) {
302 logger.error(tfce.getLocalizedMessage(), tfce);
303 }
304 catch (TransformerException te) {
305 logger.error(te.getLocalizedMessage(), te);
306 }
307
308 return false;
309 }
310 }
311 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :
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