1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /*
26 * This file is available under and governed by the GNU General Public
27 * License version 2 only, as published by the Free Software Foundation.
28 * However, the following notice accompanied the original version of this
29 * file and, per its terms, should not be removed:
30 *
31 * Copyright (c) 2004 World Wide Web Consortium,
32 *
33 * (Massachusetts Institute of Technology, European Research Consortium for
34 * Informatics and Mathematics, Keio University). All Rights Reserved. This
35 * work is distributed under the W3C(r) Software License [1] in the hope that
36 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
37 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
38 *
39 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
40 */
41
42
43 package org.w3c.dom.bootstrap;
44
45 import java.io.BufferedReader;
46 import java.io.InputStream;
47 import java.io.InputStreamReader;
48 import java.lang.reflect.InvocationTargetException;
49 import java.security.AccessController;
50 import java.security.PrivilegedAction;
51 import java.util.ArrayList;
52 import java.util.List;
53 import java.util.StringTokenizer;
54 import org.w3c.dom.DOMImplementation;
55 import org.w3c.dom.DOMImplementationList;
56 import org.w3c.dom.DOMImplementationSource;
57
58 /**
59 * A factory that enables applications to obtain instances of
60 * <code>DOMImplementation</code>.
61 *
62 * <p>
63 * Example:
64 * </p>
65 *
66 * <pre class='example'>
67 * // get an instance of the DOMImplementation registry
68 * DOMImplementationRegistry registry =
69 * DOMImplementationRegistry.newInstance();
70 * // get a DOM implementation the Level 3 XML module
71 * DOMImplementation domImpl =
72 * registry.getDOMImplementation("XML 3.0");
73 * </pre>
74 *
75 * <p>
76 * This provides an application with an implementation-independent starting
77 * point. DOM implementations may modify this class to meet new security
78 * standards or to provide *additional* fallbacks for the list of
79 * DOMImplementationSources.
80 * </p>
81 *
82 * @see DOMImplementation
83 * @see DOMImplementationSource
84 * @since 1.5, DOM Level 3
85 */
86 public final class DOMImplementationRegistry {
87 /**
88 * The system property to specify the
89 * DOMImplementationSource class names.
90 */
91 public static final String PROPERTY =
92 "org.w3c.dom.DOMImplementationSourceList";
93
94 /**
95 * Default columns per line.
96 */
97 private static final int DEFAULT_LINE_LENGTH = 80;
98
99 /**
100 * The list of DOMImplementationSources.
101 */
102 private List<DOMImplementationSource> sources;
103
104 /**
105 * Default class name.
106 */
107 private static final String FALLBACK_CLASS =
108 "com.sun.org.apache.xerces.internal.dom.DOMXSImplementationSourceImpl";
109 private static final String DEFAULT_PACKAGE =
110 "com.sun.org.apache.xerces.internal.dom";
111 /**
112 * Private constructor.
113 * @param srcs List of DOMImplementationSources
114 */
115 private DOMImplementationRegistry(final List<DOMImplementationSource> srcs) {
116 sources = srcs;
117 }
118
119 /**
120 * Obtain a new instance of a <code>DOMImplementationRegistry</code>.
121 *
122
123 * The <code>DOMImplementationRegistry</code> is initialized by the
124 * application or the implementation, depending on the context, by
125 * first checking the value of the Java system property
126 * <code>org.w3c.dom.DOMImplementationSourceList</code> and
127 * the service provider whose contents are at
128 * "<code>META_INF/services/org.w3c.dom.DOMImplementationSourceList</code>".
129 * The value of this property is a white-space separated list of
130 * names of availables classes implementing the
131 * <code>DOMImplementationSource</code> interface. Each class listed
132 * in the class name list is instantiated and any exceptions
133 * encountered are thrown to the application.
134 *
135 * @return an initialized instance of DOMImplementationRegistry
136 * @throws ClassNotFoundException
137 * If any specified class can not be found
138 * @throws InstantiationException
139 * If any specified class is an interface or abstract class
140 * @throws IllegalAccessException
141 * If the default constructor of a specified class is not accessible
142 * @throws ClassCastException
143 * If any specified class does not implement
144 * <code>DOMImplementationSource</code>
145 */
146 public static DOMImplementationRegistry newInstance()
147 throws
148 ClassNotFoundException,
149 InstantiationException,
150 IllegalAccessException,
151 ClassCastException {
152 List<DOMImplementationSource> sources = new ArrayList<>();
153
154 ClassLoader classLoader = getClassLoader();
155 // fetch system property:
156 String p = getSystemProperty(PROPERTY);
157
158 //
159 // if property is not specified then use contents of
160 // META_INF/org.w3c.dom.DOMImplementationSourceList from classpath
161 if (p == null) {
162 p = getServiceValue(classLoader);
163 }
164 if (p == null) {
165 //
166 // DOM Implementations can modify here to add *additional* fallback
167 // mechanisms to access a list of default DOMImplementationSources.
168 //fall back to JAXP implementation class DOMXSImplementationSourceImpl
169 p = FALLBACK_CLASS;
170 }
171 if (p != null) {
172 StringTokenizer st = new StringTokenizer(p);
173 while (st.hasMoreTokens()) {
174 String sourceName = st.nextToken();
175 // make sure we have access to restricted packages
176 boolean internal = false;
177 if (System.getSecurityManager() != null) {
178 if (sourceName != null && sourceName.startsWith(DEFAULT_PACKAGE)) {
179 internal = true;
180 }
181 }
182 Class<?> sourceClass = null;
183 if (classLoader != null && !internal) {
184 sourceClass = classLoader.loadClass(sourceName);
185 } else {
186 sourceClass = Class.forName(sourceName);
187 }
188 try {
189 DOMImplementationSource source =
190 (DOMImplementationSource) sourceClass.getConstructor().newInstance();
191 sources.add(source);
192 } catch (NoSuchMethodException | InvocationTargetException e) {
193 throw new InstantiationException(e.getMessage());
194 }
195 }
196 }
197 return new DOMImplementationRegistry(sources);
198 }
199
200 /**
201 * Return the first implementation that has the desired
202 * features, or <code>null</code> if none is found.
203 *
204 * @param features
205 * A string that specifies which features are required. This is
206 * a space separated list in which each feature is specified by
207 * its name optionally followed by a space and a version number.
208 * This is something like: "XML 1.0 Traversal +Events 2.0"
209 * @return An implementation that has the desired features,
210 * or <code>null</code> if none found.
211 */
212 public DOMImplementation getDOMImplementation(final String features) {
213 int size = sources.size();
214 String name = null;
215 for (int i = 0; i < size; i++) {
216 DOMImplementationSource source = sources.get(i);
217 DOMImplementation impl = source.getDOMImplementation(features);
218 if (impl != null) {
219 return impl;
220 }
221 }
222 return null;
223 }
224
225 /**
226 * Return a list of implementations that support the
227 * desired features.
228 *
229 * @param features
230 * A string that specifies which features are required. This is
231 * a space separated list in which each feature is specified by
232 * its name optionally followed by a space and a version number.
233 * This is something like: "XML 1.0 Traversal +Events 2.0"
234 * @return A list of DOMImplementations that support the desired features.
235 */
236 public DOMImplementationList getDOMImplementationList(final String features) {
237 final List<DOMImplementation> implementations = new ArrayList<>();
238 int size = sources.size();
239 for (int i = 0; i < size; i++) {
240 DOMImplementationSource source = sources.get(i);
241 DOMImplementationList impls =
242 source.getDOMImplementationList(features);
243 for (int j = 0; j < impls.getLength(); j++) {
244 DOMImplementation impl = impls.item(j);
245 implementations.add(impl);
246 }
247 }
248 return new DOMImplementationList() {
249 public DOMImplementation item(final int index) {
250 if (index >= 0 && index < implementations.size()) {
251 try {
252 return implementations.get(index);
253 } catch (IndexOutOfBoundsException e) {
254 return null;
255 }
256 }
257 return null;
258 }
259
260 public int getLength() {
261 return implementations.size();
262 }
263 };
264 }
265
266 /**
267 * Register an implementation.
268 *
269 * @param s The source to be registered, may not be <code>null</code>
270 */
271 public void addSource(final DOMImplementationSource s) {
272 if (s == null) {
273 throw new NullPointerException();
274 }
275 if (!sources.contains(s)) {
276 sources.add(s);
277 }
278 }
279
280 /**
281 *
282 * Gets a class loader.
283 *
284 * @return A class loader, possibly <code>null</code>
285 */
286 private static ClassLoader getClassLoader() {
287 try {
288 ClassLoader contextClassLoader = getContextClassLoader();
289
290 if (contextClassLoader != null) {
291 return contextClassLoader;
292 }
293 } catch (Exception e) {
294 // Assume that the DOM application is in a JRE 1.1, use the
295 // current ClassLoader
296 return DOMImplementationRegistry.class.getClassLoader();
297 }
298 return DOMImplementationRegistry.class.getClassLoader();
299 }
300
301 /**
302 * This method attempts to return the first line of the resource
303 * META_INF/services/org.w3c.dom.DOMImplementationSourceList
304 * from the provided ClassLoader.
305 *
306 * @param classLoader classLoader, may not be <code>null</code>.
307 * @return first line of resource, or <code>null</code>
308 */
309 private static String getServiceValue(final ClassLoader classLoader) {
310 String serviceId = "META-INF/services/" + PROPERTY;
311 // try to find services in CLASSPATH
312 try {
313 InputStream is = getResourceAsStream(classLoader, serviceId);
314
315 if (is != null) {
316 BufferedReader rd;
317 try {
318 rd =
319 new BufferedReader(new InputStreamReader(is, "UTF-8"),
320 DEFAULT_LINE_LENGTH);
321 } catch (java.io.UnsupportedEncodingException e) {
322 rd =
323 new BufferedReader(new InputStreamReader(is),
324 DEFAULT_LINE_LENGTH);
325 }
326 String serviceValue = rd.readLine();
327 rd.close();
328 if (serviceValue != null && serviceValue.length() > 0) {
329 return serviceValue;
330 }
331 }
332 } catch (Exception ex) {
333 return null;
334 }
335 return null;
336 }
337
338 /**
339 * This method returns the ContextClassLoader.
340 *
341 * @return The Context Classloader
342 */
343 private static ClassLoader getContextClassLoader() {
344 return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
345 @Override
346 public ClassLoader run() {
347 ClassLoader classLoader = null;
348 try {
349 classLoader =
350 Thread.currentThread().getContextClassLoader();
351 } catch (SecurityException ex) {
352 }
353 return classLoader;
354 }
355 });
356 }
357
358 /**
359 * This method returns the system property indicated by the specified name
360 * after checking access control privileges.
361 *
362 * @param name the name of the system property
363 * @return the system property
364 */
365 private static String getSystemProperty(final String name) {
366 return AccessController.doPrivileged(new PrivilegedAction<String>() {
367 @Override
368 public String run() {
369 return System.getProperty(name);
370 }
371 });
372 }
373
374 /**
375 * This method returns an Inputstream for the reading resource
376 * META_INF/services/org.w3c.dom.DOMImplementationSourceList after checking
377 * access control privileges.
378 *
379 * @param classLoader classLoader
380 * @param name the resource
381 * @return an Inputstream for the resource specified
382 */
383 private static InputStream getResourceAsStream(final ClassLoader classLoader,
384 final String name) {
385 return AccessController.doPrivileged(new PrivilegedAction<InputStream>() {
386 @Override
387 public InputStream run() {
388 InputStream ris;
389 if (classLoader == null) {
390 ris =
391 ClassLoader.getSystemResourceAsStream(name);
392 } else {
393 ris = classLoader.getResourceAsStream(name);
394 }
395 return ris;
396 }
397 });
398 }
399 }