1 /*
2 * Copyright (c) 2003, 2005, 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.validation;
27
28 import java.io.File;
29 import java.lang.reflect.Method;
30 import java.lang.reflect.Modifier;
31 import java.net.URL;
32 import java.security.AccessControlContext;
33 import java.security.AccessController;
34 import java.security.PrivilegedAction;
35 import java.util.Properties;
36 import java.util.ServiceConfigurationError;
37 import java.util.ServiceLoader;
38
39 /**
40 * Implementation of {@link SchemaFactory#newInstance(String)}.
41 *
42 * @author <a href="Kohsuke.Kawaguchi@Sun.com">Kohsuke Kawaguchi</a>
43 * @version $Revision: 1.8 $, $Date: 2010-11-01 04:36:13 $
44 * @since 1.5
45 */
46 class SchemaFactoryFinder {
47
48 /** debug support code. */
49 private static boolean debug = false;
50 /**
51 *<p> Take care of restrictions imposed by java security model </p>
52 */
53 private static final SecuritySupport ss = new SecuritySupport();
54 /**
55 * <p>Cache properties for performance.</p>
56 */
57 private static final Properties cacheProps = new Properties();
58 /**
59 * <p>First time requires initialization overhead.</p>
60 */
61 private static volatile boolean firstTime = true;
62
63 static {
64 // Use try/catch block to support applets
65 try {
66 debug = ss.getSystemProperty("jaxp.debug") != null;
67 } catch (Exception _) {
68 debug = false;
69 }
70 }
71
72 /**
73 * <p>Conditional debug printing.</p>
74 *
75 * @param msg to print
76 */
77 private static void debugPrintln(String msg) {
78 if (debug) {
79 System.err.println("JAXP: " + msg);
80 }
81 }
82
83 /**
84 * <p><code>ClassLoader</code> to use to find <code>SchemaFactory</code>.</p>
85 */
86 private final ClassLoader classLoader;
87
88 /**
89 * <p>Constructor that specifies <code>ClassLoader</code> to use
90 * to find <code>SchemaFactory</code>.</p>
91 *
92 * @param loader
93 * to be used to load resource, {@link SchemaFactory}, and
94 * {@link SchemaFactoryLoader} implementations during
95 * the resolution process.
96 * If this parameter is null, the default system class loader
97 * will be used.
98 */
99 public SchemaFactoryFinder(ClassLoader loader) {
100 this.classLoader = loader;
101 if( debug ) {
102 debugDisplayClassLoader();
103 }
104 }
105
106 private void debugDisplayClassLoader() {
107 try {
108 if( classLoader == ss.getContextClassLoader() ) {
109 debugPrintln("using thread context class loader ("+classLoader+") for search");
110 return;
111 }
112 } catch( Throwable _ ) {
113 // getContextClassLoader() undefined in JDK1.1
114 }
115
116 if( classLoader==ClassLoader.getSystemClassLoader() ) {
117 debugPrintln("using system class loader ("+classLoader+") for search");
118 return;
119 }
120
121 debugPrintln("using class loader ("+classLoader+") for search");
122 }
123
124 /**
125 * <p>Creates a new {@link SchemaFactory} object for the specified
126 * schema language.</p>
127 *
128 * @param schemaLanguage
129 * See {@link SchemaFactory Schema Language} table in <code>SchemaFactory</code>
130 * for the list of available schema languages.
131 *
132 * @return <code>null</code> if the callee fails to create one.
133 *
134 * @throws NullPointerException
135 * If the <code>schemaLanguage</code> parameter is null.
136 * @throws SchemaFactoryConfigurationError
137 * If a configuration error is encountered.
138 */
139 public SchemaFactory newFactory(String schemaLanguage) {
140 if(schemaLanguage==null) {
141 throw new NullPointerException();
142 }
143 SchemaFactory f = _newFactory(schemaLanguage);
144 if (f != null) {
145 debugPrintln("factory '" + f.getClass().getName() + "' was found for " + schemaLanguage);
146 } else {
147 debugPrintln("unable to find a factory for " + schemaLanguage);
148 }
149 return f;
150 }
151
152 /**
153 * <p>Lookup a <code>SchemaFactory</code> for the given <code>schemaLanguage</code>.</p>
154 *
155 * @param schemaLanguage Schema language to lookup <code>SchemaFactory</code> for.
156 *
157 * @return <code>SchemaFactory</code> for the given <code>schemaLanguage</code>.
158 */
159 private SchemaFactory _newFactory(String schemaLanguage) {
160 SchemaFactory sf;
161
162 String propertyName = SERVICE_CLASS.getName() + ":" + schemaLanguage;
163
164 // system property look up
165 try {
166 debugPrintln("Looking up system property '"+propertyName+"'" );
167 String r = ss.getSystemProperty(propertyName);
168 if(r!=null) {
169 debugPrintln("The value is '"+r+"'");
170 sf = createInstance(r, true);
171 if(sf!=null) return sf;
172 } else
173 debugPrintln("The property is undefined.");
174 } catch( Throwable t ) {
175 if( debug ) {
176 debugPrintln("failed to look up system property '"+propertyName+"'" );
177 t.printStackTrace();
178 }
179 }
180
181 String javah = ss.getSystemProperty( "java.home" );
182 String configFile = javah + File.separator +
183 "lib" + File.separator + "jaxp.properties";
184
185 String factoryClassName;
186
187 // try to read from $java.home/lib/jaxp.properties
188 try {
189 if(firstTime){
190 synchronized(cacheProps){
191 if(firstTime){
192 File f=new File( configFile );
193 firstTime = false;
194 if(ss.doesFileExist(f)){
195 debugPrintln("Read properties file " + f);
196 cacheProps.load(ss.getFileInputStream(f));
197 }
198 }
199 }
200 }
201 factoryClassName = cacheProps.getProperty(propertyName);
202 debugPrintln("found " + factoryClassName + " in $java.home/jaxp.properties");
203
204 if (factoryClassName != null) {
205 sf = createInstance(factoryClassName, true);
206 if(sf != null){
207 return sf;
208 }
209 }
210 } catch (Exception ex) {
211 if (debug) {
212 ex.printStackTrace();
213 }
214 }
215
216 // Try with ServiceLoader
217 final SchemaFactory factoryImpl = findServiceProvider(schemaLanguage);
218 assert factoryImpl == null || factoryImpl.isSchemaLanguageSupported(schemaLanguage);
219 if (factoryImpl != null) {
220 return factoryImpl;
221 }
222
223 // platform default
224 if(schemaLanguage.equals("http://www.w3.org/2001/XMLSchema")) {
225 debugPrintln("attempting to use the platform default XML Schema validator");
226 return createInstance("com.sun.org.apache.xerces.internal.jaxp.validation.XMLSchemaFactory", true);
227 }
228
229 debugPrintln("all things were tried, but none was found. bailing out.");
230 return null;
231 }
232
233 /** <p>Create class using appropriate ClassLoader.</p>
234 *
235 * @param className Name of class to create.
236 * @return Created class or <code>null</code>.
237 */
238 private Class<?> createClass(String className) {
239 Class<?> clazz;
240
241 // use approprite ClassLoader
242 try {
243 if (classLoader != null) {
244 clazz = Class.forName(className, false, classLoader);
245 } else {
246 clazz = Class.forName(className);
247 }
248 } catch (Throwable t) {
249 if (debug) {
250 t.printStackTrace();
251 }
252 return null;
253 }
254
255 return clazz;
256 }
257
258 /**
259 * <p>Creates an instance of the specified and returns it.</p>
260 *
261 * @param className
262 * fully qualified class name to be instantiated.
263 *
264 * @return null
265 * if it fails. Error messages will be printed by this method.
266 */
267 SchemaFactory createInstance( String className ) {
268 return createInstance( className, false );
269 }
270
271 SchemaFactory createInstance( String className, boolean useServicesMechanism ) {
272 SchemaFactory schemaFactory = null;
273
274 debugPrintln("createInstance(" + className + ")");
275
276 // get Class from className
277 Class<?> clazz = createClass(className);
278 if (clazz == null) {
279 debugPrintln("failed to getClass(" + className + ")");
280 return null;
281 }
282 debugPrintln("loaded " + className + " from " + which(clazz));
283
284 // instantiate Class as a SchemaFactory
285 try {
286 if (!SchemaFactory.class.isAssignableFrom(clazz)) {
287 throw new ClassCastException(clazz.getName()
288 + " cannot be cast to " + SchemaFactory.class);
289 }
290 if (!useServicesMechanism) {
291 schemaFactory = newInstanceNoServiceLoader(clazz);
292 }
293 if (schemaFactory == null) {
294 schemaFactory = (SchemaFactory) clazz.newInstance();
295 }
296 } catch (ClassCastException classCastException) {
297 debugPrintln("could not instantiate " + clazz.getName());
298 if (debug) {
299 classCastException.printStackTrace();
300 }
301 return null;
302 } catch (IllegalAccessException illegalAccessException) {
303 debugPrintln("could not instantiate " + clazz.getName());
304 if (debug) {
305 illegalAccessException.printStackTrace();
306 }
307 return null;
308 } catch (InstantiationException instantiationException) {
309 debugPrintln("could not instantiate " + clazz.getName());
310 if (debug) {
311 instantiationException.printStackTrace();
312 }
313 return null;
314 }
315
316 return schemaFactory;
317 }
318
319 /**
320 * Try to construct using newXMLSchemaFactoryNoServiceLoader
321 * method if available.
322 */
323 private static SchemaFactory newInstanceNoServiceLoader(
324 Class<?> providerClass
325 ) {
326 // Retain maximum compatibility if no security manager.
327 if (System.getSecurityManager() == null) {
328 return null;
329 }
330 try {
331 final Method creationMethod =
332 providerClass.getDeclaredMethod(
333 "newXMLSchemaFactoryNoServiceLoader"
334 );
335 final int modifiers = creationMethod.getModifiers();
336
337 // Do not call the method if it's not public static.
338 if (!Modifier.isStatic(modifiers) || !Modifier.isPublic(modifiers)) {
339 return null;
340 }
341
342 // Only calls "newXMLSchemaFactoryNoServiceLoader" if it's
343 // declared to return an instance of SchemaFactory.
344 final Class<?> returnType = creationMethod.getReturnType();
345 if (SERVICE_CLASS.isAssignableFrom(returnType)) {
346 return SERVICE_CLASS.cast(creationMethod.invoke(null, (Object[])null));
347 } else {
348 // Should not happen since
349 // XMLSchemaFactory.newXMLSchemaFactoryNoServiceLoader is
350 // declared to return XMLSchemaFactory.
351 throw new ClassCastException(returnType
352 + " cannot be cast to " + SERVICE_CLASS);
353 }
354 } catch(ClassCastException e) {
355 throw new SchemaFactoryConfigurationError(e.getMessage(), e);
356 } catch (NoSuchMethodException exc) {
357 return null;
358 } catch (Exception exc) {
359 return null;
360 }
361 }
362
363 // Call isSchemaLanguageSupported with initial context.
364 private boolean isSchemaLanguageSupportedBy(final SchemaFactory factory,
365 final String schemaLanguage,
366 AccessControlContext acc) {
367 return AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
368 public Boolean run() {
369 return factory.isSchemaLanguageSupported(schemaLanguage);
370 }
371 }, acc);
372 }
373
374 /**
375 * Finds a service provider subclass of SchemaFactory that supports the
376 * given schema language using the ServiceLoader.
377 *
378 * @param schemaLanguage The schema language for which we seek a factory.
379 * @return A SchemaFactory supporting the specified schema language, or null
380 * if none is found.
381 * @throws SchemaFactoryConfigurationError if a configuration error is found.
382 */
383 private SchemaFactory findServiceProvider(final String schemaLanguage) {
384 assert schemaLanguage != null;
385 // store current context.
386 final AccessControlContext acc = AccessController.getContext();
387 try {
388 return AccessController.doPrivileged(new PrivilegedAction<SchemaFactory>() {
389 public SchemaFactory run() {
390 final ServiceLoader<SchemaFactory> loader =
391 ServiceLoader.load(SERVICE_CLASS);
392 for (SchemaFactory factory : loader) {
393 // restore initial context to call
394 // factory.isSchemaLanguageSupported
395 if (isSchemaLanguageSupportedBy(factory, schemaLanguage, acc)) {
396 return factory;
397 }
398 }
399 return null; // no factory found.
400 }
401 });
402 } catch (ServiceConfigurationError error) {
403 throw new SchemaFactoryConfigurationError(
404 "Provider for " + SERVICE_CLASS + " cannot be created", error);
405 }
406 }
407
408 private static final Class<SchemaFactory> SERVICE_CLASS = SchemaFactory.class;
409
410
411 private static String which( Class<?> clazz ) {
412 return which( clazz.getName(), clazz.getClassLoader() );
413 }
414
415 /**
416 * <p>Search the specified classloader for the given classname.</p>
417 *
418 * @param classname the fully qualified name of the class to search for
419 * @param loader the classloader to search
420 *
421 * @return the source location of the resource, or null if it wasn't found
422 */
423 private static String which(String classname, ClassLoader loader) {
424
425 String classnameAsResource = classname.replace('.', '/') + ".class";
426
427 if( loader==null ) loader = ClassLoader.getSystemClassLoader();
428
429 //URL it = loader.getResource(classnameAsResource);
430 URL it = ss.getResourceAsURL(loader, classnameAsResource);
431 if (it != null) {
432 return it.toString();
433 } else {
434 return null;
435 }
436 }
437 }