1 /*
2 * Copyright (c) 2003, 2013, 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.parsers;
27
28 import java.io.File;
29 import java.security.AccessController;
30 import java.security.PrivilegedAction;
31 import java.util.Iterator;
32 import java.util.Properties;
33 import java.util.ServiceConfigurationError;
34 import java.util.ServiceLoader;
35
36 /**
37 * <p>Implements pluggable Parsers.</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.xerces.internal";
47 /**
48 * Internal debug flag.
49 */
50 private static boolean debug = false;
51
52 /**
53 * Cache for properties in java.home/lib/jaxp.properties
54 */
55 private static final Properties cacheProps = new Properties();
56
57 /**
58 * Flag indicating if properties from java.home/lib/jaxp.properties
59 * have been cached.
60 */
61 static volatile boolean firstTime = true;
62
63 /**
64 * Security support class use to check access control before
65 * getting certain system resources.
66 */
67 private static final SecuritySupport ss = new SecuritySupport();
68
69 // Define system property "jaxp.debug" to get output
70 static {
71 // Use try/catch block to support applets, which throws
72 // SecurityException out of this code.
73 try {
74 String val = ss.getSystemProperty("jaxp.debug");
75 // Allow simply setting the prop to turn on debug
76 debug = val != null && !"false".equals(val);
77 }
78 catch (SecurityException se) {
79 debug = false;
80 }
81 }
82
83 private static void dPrint(String msg) {
84 if (debug) {
85 System.err.println("JAXP: " + msg);
86 }
87 }
88
89 /**
90 * Attempt to load a class using the class loader supplied. If that fails
91 * and fall back is enabled, the current (i.e. bootstrap) class loader is
92 * tried.
93 *
94 * If the class loader supplied is <code>null</code>, first try using the
95 * context class loader followed by the current (i.e. bootstrap) class
96 * loader.
97 *
98 * Use bootstrap classLoader if cl = null and useBSClsLoader is true
99 */
100 static private Class<?> getProviderClass(String className, ClassLoader cl,
101 boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
102 {
103 try {
104 if (cl == null) {
105 if (useBSClsLoader) {
106 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
107 } else {
108 cl = ss.getContextClassLoader();
109 if (cl == null) {
110 throw new ClassNotFoundException();
111 }
112 else {
113 return Class.forName(className, false, cl);
114 }
115 }
116 }
117 else {
118 return Class.forName(className, false, cl);
119 }
120 }
121 catch (ClassNotFoundException e1) {
122 if (doFallback) {
123 // Use current class loader - should always be bootstrap CL
124 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
125 }
126 else {
127 throw e1;
128 }
129 }
130 }
131
132 /**
133 * Create an instance of a class. Delegates to method
134 * <code>getProviderClass()</code> in order to load the class.
135 *
136 * @param type Base class / Service interface of the factory to
137 * instantiate.
138 *
139 * @param className Name of the concrete class corresponding to the
140 * service provider
141 *
142 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
143 * current <code>Thread</code>'s context classLoader is used to load the factory class.
144 *
145 * @param doFallback True if the current ClassLoader should be tried as
146 * a fallback if the class is not found using cl
147 */
148 static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
149 boolean doFallback)
150 throws FactoryConfigurationError
151 {
152 return newInstance(type, className, cl, doFallback, false);
153 }
154
155 /**
156 * Create an instance of a class. Delegates to method
157 * <code>getProviderClass()</code> in order to load the class.
158 *
159 * @param type Base class / Service interface of the factory to
160 * instantiate.
161 *
162 * @param className Name of the concrete class corresponding to the
163 * service provider
164 *
165 * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
166 * current <code>Thread</code>'s context classLoader is used to load the factory class.
167 *
168 * @param doFallback True if the current ClassLoader should be tried as
169 * a fallback if the class is not found using cl
170 *
171 * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
172 * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
173 */
174 static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
175 boolean doFallback, boolean useBSClsLoader)
176 throws FactoryConfigurationError
177 {
178 assert type != null;
179 // make sure we have access to restricted packages
180 if (System.getSecurityManager() != null) {
181 if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
182 cl = null;
183 useBSClsLoader = true;
184 }
185 }
186
187 try {
188 Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
189 if (!type.isAssignableFrom(providerClass)) {
190 throw new ClassCastException(className + " cannot be cast to " + type.getName());
191 }
192 Object instance = providerClass.newInstance();
193 if (debug) { // Extra check to avoid computing cl strings
194 dPrint("created new instance of " + providerClass +
195 " using ClassLoader: " + cl);
196 }
197 return type.cast(instance);
198 }
199 catch (ClassNotFoundException x) {
200 throw new FactoryConfigurationError(x,
201 "Provider " + className + " not found");
202 }
203 catch (Exception x) {
204 throw new FactoryConfigurationError(x,
205 "Provider " + className + " could not be instantiated: " + x);
206 }
207 }
208
209 /**
210 * Finds the implementation Class object in the specified order. Main
211 * entry point.
212 * @return Class object of factory, never null
213 *
214 * @param type Base class / Service interface of the
215 * factory to find.
216 * @param fallbackClassName Implementation class name, if nothing else
217 * is found. Use null to mean no fallback.
218 *
219 * Package private so this code can be shared.
220 */
221 static <T> T find(Class<T> type, String fallbackClassName)
222 throws FactoryConfigurationError
223 {
224 final String factoryId = type.getName();
225 dPrint("find factoryId =" + factoryId);
226
227 // Use the system property first
228 try {
229 String systemProp = ss.getSystemProperty(factoryId);
230 if (systemProp != null) {
231 dPrint("found system property, value=" + systemProp);
232 return newInstance(type, systemProp, null, true);
233 }
234 }
235 catch (SecurityException se) {
236 if (debug) se.printStackTrace();
237 }
238
239 // try to read from $java.home/lib/jaxp.properties
240 try {
241 if (firstTime) {
242 synchronized (cacheProps) {
243 if (firstTime) {
244 String configFile = ss.getSystemProperty("java.home") + File.separator +
245 "lib" + File.separator + "jaxp.properties";
246 File f = new File(configFile);
247 firstTime = false;
248 if (ss.doesFileExist(f)) {
249 dPrint("Read properties file "+f);
250 cacheProps.load(ss.getFileInputStream(f));
251 }
252 }
253 }
254 }
255 final String factoryClassName = cacheProps.getProperty(factoryId);
256
257 if (factoryClassName != null) {
258 dPrint("found in $java.home/jaxp.properties, value=" + factoryClassName);
259 return newInstance(type, factoryClassName, null, true);
260 }
261 }
262 catch (Exception ex) {
263 if (debug) ex.printStackTrace();
264 }
265
266 // Try Jar Service Provider Mechanism
267 T provider = findServiceProvider(type);
268 if (provider != null) {
269 return provider;
270 }
271 if (fallbackClassName == null) {
272 throw new FactoryConfigurationError(
273 "Provider for " + factoryId + " cannot be found");
274 }
275
276 dPrint("loaded from fallback value: " + fallbackClassName);
277 return newInstance(type, fallbackClassName, null, true);
278 }
279
280 /*
281 * Try to find provider using the ServiceLoader API
282 *
283 * @param type Base class / Service interface of the factory to find.
284 *
285 * @return instance of provider class if found or null
286 */
287 private static <T> T findServiceProvider(final Class<T> type) {
288 try {
289 return AccessController.doPrivileged(new PrivilegedAction<T>() {
290 public T run() {
291 final ServiceLoader<T> serviceLoader = ServiceLoader.load(type);
292 final Iterator<T> iterator = serviceLoader.iterator();
293 if (iterator.hasNext()) {
294 return iterator.next();
295 } else {
296 return null;
297 }
298 }
299 });
300 } catch(ServiceConfigurationError e) {
301 // It is not possible to wrap an error directly in
302 // FactoryConfigurationError - so we need to wrap the
303 // ServiceConfigurationError in a RuntimeException.
304 // The alternative would be to modify the logic in
305 // FactoryConfigurationError to allow setting a
306 // Throwable as the cause, but that could cause
307 // compatibility issues down the road.
308 final RuntimeException x = new RuntimeException(
309 "Provider for " + type + " cannot be created", e);
310 final FactoryConfigurationError error =
311 new FactoryConfigurationError(x, x.getMessage());
312 throw error;
313 }
314 }
315
316 }