1 /*
2 * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.xml.transform;
27
28 import java.io.BufferedReader;
29 import java.io.File;
30 import java.io.IOException;
31 import java.io.InputStream;
32 import java.io.InputStreamReader;
33 import java.lang.reflect.Method;
34 import java.util.Properties;
35
36 /**
37 * <p>Implements pluggable Datatypes.</p>
38 *
39 * <p>This class is duplicated for each JAXP subpackage so keep it in
40 * sync. It is package private for secure class loading.</p>
41 *
42 * @author Santiago.PericasGeertsen@sun.com
43 * @author Huizhe.Wang@oracle.com
44 */
45 class FactoryFinder {
46 private static final String DEFAULT_PACKAGE = "com.sun.org.apache.xalan.internal.";
47
48 /**
49 * Internal debug flag.
50 */
51 private static boolean debug = false;
52
53 /**
54 * Cache for properties in java.home/lib/jaxp.properties
55 */
56 static Properties cacheProps = new Properties();
57
58 /**
59 * Flag indicating if properties from java.home/lib/jaxp.properties
60 * have been cached.
61 */
62 static volatile boolean firstTime = true;
63
64 /**
65 * Security support class use to check access control before
66 * getting certain system resources.
67 */
68 static SecuritySupport ss = new SecuritySupport();
69
70 // Define system property "jaxp.debug" to get output
71 static {
72 // Use try/catch block to support applets, which throws
73 // SecurityException out of this code.
74 try {
75 String val = ss.getSystemProperty("jaxp.debug");
76 // Allow simply setting the prop to turn on debug
77 debug = val != null && !"false".equals(val);
78 }
79 catch (SecurityException se) {
80 debug = false;
81 }
82 }
83
84 private static void dPrint(String msg) {
85 if (debug) {
86 System.err.println("JAXP: " + msg);
87 }
88 }
89
90 /**
91 * Attempt to load a class using the class loader supplied. If that fails
92 * and fall back is enabled, the current (i.e. bootstrap) class loader is
93 * tried.
94 *
95 * If the class loader supplied is <code>null</code>, first try using the
96 * context class loader followed by the current (i.e. bootstrap) class
97 * loader.
98 *
99 * Use bootstrap classLoader if cl = null and useBSClsLoader is true
100 */
101 static private Class getProviderClass(String className, ClassLoader cl,
102 boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
103 {
104 try {
105 if (cl == null) {
106 if (useBSClsLoader) {
107 return Class.forName(className, true, FactoryFinder.class.getClassLoader());
108 } else {
109 cl = ss.getContextClassLoader();
110 if (cl == null) {
111 throw new ClassNotFoundException();
112 }
113 else {
114 return cl.loadClass(className);
115 }
116 }
117 }
118 else {
119 return cl.loadClass(className);
120 }
121 }
122 catch (ClassNotFoundException e1) {
123 if (doFallback) {
124 // Use current class loader - should always be bootstrap CL
125 return Class.forName(className, true, FactoryFinder.class.getClassLoader());
126 }
127 else {
128 throw e1;
129 }
130 }
131 }
132
133 /**
134 * Create an instance of a class. Delegates to method
135 * <code>getProviderClass()</code> in order to load the class.
136 *
137 * @param className Name of the concrete class corresponding to the
138 * service provider
139 *
140 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
141 * current <code>Thread</code>'s context classLoader is used to load the factory class.
142 *
143 * @param doFallback True if the current ClassLoader should be tried as
144 * a fallback if the class is not found using cl
145 */
146 static Object newInstance(String className, ClassLoader cl, boolean doFallback)
147 throws ConfigurationError
148 {
149 return newInstance(className, cl, doFallback, false, false);
150 }
151
152 /**
153 * Create an instance of a class. Delegates to method
154 * <code>getProviderClass()</code> in order to load the class.
155 *
156 * @param className Name of the concrete class corresponding to the
157 * service provider
158 *
159 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
160 * current <code>Thread</code>'s context classLoader is used to load the factory class.
161 *
162 * @param doFallback True if the current ClassLoader should be tried as
163 * a fallback if the class is not found using cl
164 *
165 * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
166 * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
167 *
168 * @param useServicesMechanism True use services mechanism
169 */
170 static Object newInstance(String className, ClassLoader cl, boolean doFallback, boolean useBSClsLoader, boolean useServicesMechanism)
171 throws ConfigurationError
172 {
173 // make sure we have access to restricted packages
174 if (System.getSecurityManager() != null) {
175 if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
176 cl = null;
177 useBSClsLoader = true;
178 }
179 }
180
181 try {
182 Class providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
183 Object instance = null;
184 if (!useServicesMechanism) {
185 instance = newInstanceNoServiceLoader(providerClass);
186 }
187 if (instance == null) {
188 instance = providerClass.newInstance();
189 }
190 if (debug) { // Extra check to avoid computing cl strings
191 dPrint("created new instance of " + providerClass +
192 " using ClassLoader: " + cl);
193 }
194 return instance;
195 }
196 catch (ClassNotFoundException x) {
197 throw new ConfigurationError(
198 "Provider " + className + " not found", x);
199 }
200 catch (Exception x) {
201 throw new ConfigurationError(
202 "Provider " + className + " could not be instantiated: " + x,
203 x);
204 }
205 }
206 /**
207 * Try to construct using newTransformerFactoryNoServiceLoader
208 * method if available.
209 */
210 private static Object newInstanceNoServiceLoader(
211 Class<?> providerClass
212 ) {
213 // Retain maximum compatibility if no security manager.
214 if (System.getSecurityManager() == null) {
215 return null;
216 }
217 try {
218 Method creationMethod =
219 providerClass.getDeclaredMethod(
220 "newTransformerFactoryNoServiceLoader"
221 );
222 return creationMethod.invoke(null, (Object[])null);
223 } catch (NoSuchMethodException exc) {
224 return null;
225 } catch (Exception exc) {
226 return null;
227 }
228 }
229 /**
230 * Finds the implementation Class object in the specified order. Main
231 * entry point.
232 * @return Class object of factory, never null
233 *
234 * @param factoryId Name of the factory to find, same as
235 * a property name
236 * @param fallbackClassName Implementation class name, if nothing else
237 * is found. Use null to mean no fallback.
238 *
239 * Package private so this code can be shared.
240 */
241 static Object find(String factoryId, String fallbackClassName)
242 throws ConfigurationError
243 {
244 dPrint("find factoryId =" + factoryId);
245 // Use the system property first
246 try {
247 String systemProp = ss.getSystemProperty(factoryId);
248 if (systemProp != null) {
249 dPrint("found system property, value=" + systemProp);
250 return newInstance(systemProp, null, true, false, true);
251 }
252 }
253 catch (SecurityException se) {
254 if (debug) se.printStackTrace();
255 }
256
257 // try to read from $java.home/lib/jaxp.properties
258 try {
259 String factoryClassName = null;
260 if (firstTime) {
261 synchronized (cacheProps) {
262 if (firstTime) {
263 String configFile = ss.getSystemProperty("java.home") + File.separator +
264 "lib" + File.separator + "jaxp.properties";
265 File f = new File(configFile);
266 firstTime = false;
267 if (ss.doesFileExist(f)) {
268 dPrint("Read properties file "+f);
269 cacheProps.load(ss.getFileInputStream(f));
270 }
271 }
272 }
273 }
274 factoryClassName = cacheProps.getProperty(factoryId);
275
276 if (factoryClassName != null) {
277 dPrint("found in $java.home/jaxp.properties, value=" + factoryClassName);
278 return newInstance(factoryClassName, null, true, false, true);
279 }
280 }
281 catch (Exception ex) {
282 if (debug) ex.printStackTrace();
283 }
284
285 // Try Jar Service Provider Mechanism
286 Object provider = findJarServiceProvider(factoryId);
287 if (provider != null) {
288 return provider;
289 }
290 if (fallbackClassName == null) {
291 throw new ConfigurationError(
292 "Provider for " + factoryId + " cannot be found", null);
293 }
294
295 dPrint("loaded from fallback value: " + fallbackClassName);
296 return newInstance(fallbackClassName, null, true, false, true);
297 }
298
299 /*
300 * Try to find provider using Jar Service Provider Mechanism
301 *
302 * @return instance of provider class if found or null
303 */
304 private static Object findJarServiceProvider(String factoryId)
305 throws ConfigurationError
306 {
307 String serviceId = "META-INF/services/" + factoryId;
308 InputStream is = null;
309
310 // First try the Context ClassLoader
311 ClassLoader cl = ss.getContextClassLoader();
312 boolean useBSClsLoader = false;
313 if (cl != null) {
314 is = ss.getResourceAsStream(cl, serviceId);
315
316 // If no provider found then try the current ClassLoader
317 if (is == null) {
318 cl = FactoryFinder.class.getClassLoader();
319 is = ss.getResourceAsStream(cl, serviceId);
320 useBSClsLoader = true;
321 }
322 } else {
323 // No Context ClassLoader, try the current ClassLoader
324 cl = FactoryFinder.class.getClassLoader();
325 is = ss.getResourceAsStream(cl, serviceId);
326 useBSClsLoader = true;
327 }
328
329 if (is == null) {
330 // No provider found
331 return null;
332 }
333
334 if (debug) { // Extra check to avoid computing cl strings
335 dPrint("found jar resource=" + serviceId + " using ClassLoader: " + cl);
336 }
337
338 BufferedReader rd;
339 try {
340 rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
341 }
342 catch (java.io.UnsupportedEncodingException e) {
343 rd = new BufferedReader(new InputStreamReader(is));
344 }
345
346 String factoryClassName = null;
347 try {
348 // XXX Does not handle all possible input as specified by the
349 // Jar Service Provider specification
350 factoryClassName = rd.readLine();
351 rd.close();
352 } catch (IOException x) {
353 // No provider found
354 return null;
355 }
356
357 if (factoryClassName != null && !"".equals(factoryClassName)) {
358 dPrint("found in resource, value=" + factoryClassName);
359
360 // Note: here we do not want to fall back to the current
361 // ClassLoader because we want to avoid the case where the
362 // resource file was found using one ClassLoader and the
363 // provider class was instantiated using a different one.
364 return newInstance(factoryClassName, cl, false, useBSClsLoader, true);
365 }
366
367 // No provider found
368 return null;
369 }
370
371 static class ConfigurationError extends Error {
372 private Exception exception;
373
374 /**
375 * Construct a new instance with the specified detail string and
376 * exception.
377 */
378 ConfigurationError(String msg, Exception x) {
379 super(msg);
380 this.exception = x;
381 }
382
383 Exception getException() {
384 return exception;
385 }
386 /**
387 * use the exception chaining mechanism of JDK1.4
388 */
389 @Override
390 public Throwable getCause() {
391 return exception;
392 }
393 }
394
395 }