1 /*
2 * Copyright (c) 2010, 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.sql.rowset;
27
28 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30 import java.sql.SQLException;
31 import java.util.PropertyPermission;
32 import java.util.ServiceConfigurationError;
33 import java.util.ServiceLoader;
34 import sun.reflect.misc.ReflectUtil;
35
36 /**
37 * A factory API that enables applications to obtain a
38 * {@code RowSetFactory} implementation that can be used to create different
39 * types of {@code RowSet} implementations.
40 * <p>
41 * Example:
42 * </p>
43 * <pre>
44 * RowSetFactory aFactory = RowSetProvider.newFactory();
45 * CachedRowSet crs = aFactory.createCachedRowSet();
46 * ...
47 * RowSetFactory rsf = RowSetProvider.newFactory("com.sun.rowset.RowSetFactoryImpl", null);
48 * WebRowSet wrs = rsf.createWebRowSet();
49 * </pre>
50 *<p>
51 * Tracing of this class may be enabled by setting the System property
52 * {@code javax.sql.rowset.RowSetFactory.debug} to any value but {@code false}.
53 * </p>
54 *
55 * @author Lance Andersen
56 * @since 1.7
57 */
58 public class RowSetProvider {
59
60 private static final String ROWSET_DEBUG_PROPERTY = "javax.sql.rowset.RowSetProvider.debug";
61 private static final String ROWSET_FACTORY_IMPL = "com.sun.rowset.RowSetFactoryImpl";
62 private static final String ROWSET_FACTORY_NAME = "javax.sql.rowset.RowSetFactory";
63 /**
64 * Internal debug flag.
65 */
66 private static boolean debug = true;
67
68
69 static {
70 // Check to see if the debug property is set
71 String val = getSystemProperty(ROWSET_DEBUG_PROPERTY);
72 // Allow simply setting the prop to turn on debug
73 debug = val != null && !"false".equals(val);
74 }
75
76 /**
77 * RowSetProvider constructor
78 */
79 protected RowSetProvider () {
80 }
81
82 /**
83 * <p>Creates a new instance of a <code>RowSetFactory</code>
84 * implementation. This method uses the following
85 * look up order to determine
86 * the <code>RowSetFactory</code> implementation class to load:</p>
87 * <ul>
88 * <li>
89 * The System property {@code javax.sql.rowset.RowSetFactory}. For example:
90 * <ul>
91 * <li>
92 * -Djavax.sql.rowset.RowSetFactory=com.sun.rowset.RowSetFactoryImpl
93 * </li>
94 * </ul>
95 * <li>
96 * The {@link ServiceLoader} API. The {@code ServiceLoader} API will look
97 * for a class name in the file
98 * {@code META-INF/services/javax.sql.rowset.RowSetFactory}
99 * in jars available to the runtime. For example, to have the RowSetFactory
100 * implementation {@code com.sun.rowset.RowSetFactoryImpl } loaded, the
101 * entry in {@code META-INF/services/javax.sql.rowset.RowSetFactory} would be:
102 * <ul>
103 * <li>
104 * {@code com.sun.rowset.RowSetFactoryImpl }
105 * </li>
106 * </ul>
107 * </li>
108 * <li>
109 * Platform default <code>RowSetFactory</code> instance.
110 * </li>
111 * </ul>
112 *
113 * <p>Once an application has obtained a reference to a {@code RowSetFactory},
114 * it can use the factory to obtain RowSet instances.</p>
115 *
116 * @return New instance of a <code>RowSetFactory</code>
117 *
118 * @throws SQLException if the default factory class cannot be loaded,
119 * instantiated. The cause will be set to actual Exception
120 *
121 * @see ServiceLoader
122 * @since 1.7
123 */
124 public static RowSetFactory newFactory()
125 throws SQLException {
126 // Use the system property first
127 RowSetFactory factory = null;
128 String factoryClassName = null;
129 try {
130 trace("Checking for Rowset System Property...");
131 factoryClassName = getSystemProperty(ROWSET_FACTORY_NAME);
132 if (factoryClassName != null) {
133 trace("Found system property, value=" + factoryClassName);
134 if (factoryClassName.equals(ROWSET_FACTORY_IMPL)) {
135 return defaultRowSetFactory();
136 }
137 // getFactoryClass takes care of adding the read edge if
138 // necessary
139 @SuppressWarnings("deprecation")
140 Object o = getFactoryClass(factoryClassName, null, false).newInstance();
141 factory = (RowSetFactory) o;
142 }
143 } catch (Exception e) {
144 throw new SQLException( "RowSetFactory: " + factoryClassName +
145 " could not be instantiated: ", e);
146 }
147
148 // Check to see if we found the RowSetFactory via a System property
149 if (factory == null) {
150 // If the RowSetFactory is not found via a System Property, now
151 // look it up via the ServiceLoader API and if not found, use the
152 // Java SE default.
153 factory = loadViaServiceLoader();
154 }
155 return factory == null ? defaultRowSetFactory() : factory;
156 }
157
158 private static RowSetFactory defaultRowSetFactory() {
159 return new com.sun.rowset.RowSetFactoryImpl();
160 }
161
162 /**
163 * <p>Creates a new instance of a <code>RowSetFactory</code> from the
164 * specified factory class name.
165 * This function is useful when there are multiple providers in the classpath.
166 * It gives more control to the application as it can specify which provider
167 * should be loaded.</p>
168 *
169 * <p>Once an application has obtained a reference to a <code>RowSetFactory</code>
170 * it can use the factory to obtain RowSet instances.</p>
171 *
172 * @param factoryClassName fully qualified factory class name that
173 * provides an implementation of <code>javax.sql.rowset.RowSetFactory</code>.
174 *
175 * @param cl <code>ClassLoader</code> used to load the factory
176 * class. If <code>null</code> current <code>Thread</code>'s context
177 * classLoader is used to load the factory class.
178 *
179 * @return New instance of a <code>RowSetFactory</code>
180 *
181 * @throws SQLException if <code>factoryClassName</code> is
182 * <code>null</code>, or the factory class cannot be loaded, instantiated.
183 *
184 * @see #newFactory()
185 *
186 * @since 1.7
187 */
188 public static RowSetFactory newFactory(String factoryClassName, ClassLoader cl)
189 throws SQLException {
190
191 trace("***In newInstance()");
192
193 if(factoryClassName == null) {
194 throw new SQLException("Error: factoryClassName cannot be null");
195 }
196 try {
197 ReflectUtil.checkPackageAccess(factoryClassName);
198 } catch (java.security.AccessControlException e) {
199 throw new SQLException("Access Exception",e);
200 }
201
202 try {
203 // getFactoryClass takes care of adding the read edge if
204 // necessary
205 Class<?> providerClass = getFactoryClass(factoryClassName, cl, false);
206 @SuppressWarnings("deprecation")
207 RowSetFactory instance = (RowSetFactory) providerClass.newInstance();
208 if (debug) {
209 trace("Created new instance of " + providerClass +
210 " using ClassLoader: " + cl);
211 }
212 return instance;
213 } catch (ClassNotFoundException x) {
214 throw new SQLException(
215 "Provider " + factoryClassName + " not found", x);
216 } catch (Exception x) {
217 throw new SQLException(
218 "Provider " + factoryClassName + " could not be instantiated: " + x,
219 x);
220 }
221 }
222
223 /*
224 * Returns the class loader to be used.
225 * @return The ClassLoader to use.
226 *
227 */
228 static private ClassLoader getContextClassLoader() throws SecurityException {
229 return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
230
231 public ClassLoader run() {
232 ClassLoader cl = null;
233
234 cl = Thread.currentThread().getContextClassLoader();
235
236 if (cl == null) {
237 cl = ClassLoader.getSystemClassLoader();
238 }
239
240 return cl;
241 }
242 });
243 }
244
245 /**
246 * Attempt to load a class using the class loader supplied. If that fails
247 * and fall back is enabled, the current (i.e. bootstrap) class loader is
248 * tried.
249 *
250 * If the class loader supplied is <code>null</code>, first try using the
251 * context class loader followed by the current class loader.
252 * @return The class which was loaded
253 */
254 static private Class<?> getFactoryClass(String factoryClassName, ClassLoader cl,
255 boolean doFallback) throws ClassNotFoundException {
256 Class<?> factoryClass = null;
257
258 try {
259 if (cl == null) {
260 cl = getContextClassLoader();
261 if (cl == null) {
262 throw new ClassNotFoundException();
263 } else {
264 factoryClass = cl.loadClass(factoryClassName);
265 }
266 } else {
267 factoryClass = cl.loadClass(factoryClassName);
268 }
269 } catch (ClassNotFoundException e) {
270 if (doFallback) {
271 // Use current class loader
272 factoryClass = Class.forName(factoryClassName, true, RowSetFactory.class.getClassLoader());
273 } else {
274 throw e;
275 }
276 }
277
278 ReflectUtil.checkPackageAccess(factoryClass);
279 return factoryClass;
280 }
281
282 /**
283 * Use the ServiceLoader mechanism to load the default RowSetFactory
284 * @return default RowSetFactory Implementation
285 */
286 static private RowSetFactory loadViaServiceLoader() throws SQLException {
287 RowSetFactory theFactory = null;
288 try {
289 trace("***in loadViaServiceLoader():");
290 for (RowSetFactory factory : ServiceLoader.load(javax.sql.rowset.RowSetFactory.class)) {
291 trace(" Loading done by the java.util.ServiceLoader :" + factory.getClass().getName());
292 theFactory = factory;
293 break;
294 }
295 } catch (ServiceConfigurationError e) {
296 throw new SQLException(
297 "RowSetFactory: Error locating RowSetFactory using Service "
298 + "Loader API: " + e, e);
299 }
300 return theFactory;
301
302 }
303
304 /**
305 * Returns the requested System Property. If a {@code SecurityException}
306 * occurs, just return NULL
307 * @param propName - System property to retrieve
308 * @return The System property value or NULL if the property does not exist
309 * or a {@code SecurityException} occurs.
310 */
311 static private String getSystemProperty(final String propName) {
312 String property = null;
313 try {
314 property = AccessController.doPrivileged(new PrivilegedAction<String>() {
315
316 public String run() {
317 return System.getProperty(propName);
318 }
319 }, null, new PropertyPermission(propName, "read"));
320 } catch (SecurityException se) {
321 trace("error getting " + propName + ": "+ se);
322 if (debug) {
323 se.printStackTrace();
324 }
325 }
326 return property;
327 }
328
329 /**
330 * Debug routine which will output tracing if the System Property
331 * -Djavax.sql.rowset.RowSetFactory.debug is set
332 * @param msg - The debug message to display
333 */
334 private static void trace(String msg) {
335 if (debug) {
336 System.err.println("###RowSets: " + msg);
337 }
338 }
339 }