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 Class<?> c = getFactoryClass(factoryClassName, null, false);
140 factory = (RowSetFactory) c.newInstance();
141 }
142 } catch (Exception e) {
143 throw new SQLException( "RowSetFactory: " + factoryClassName +
144 " could not be instantiated: ", e);
145 }
146
147 // Check to see if we found the RowSetFactory via a System property
148 if (factory == null) {
149 // If the RowSetFactory is not found via a System Property, now
150 // look it up via the ServiceLoader API and if not found, use the
151 // Java SE default.
152 factory = loadViaServiceLoader();
153 }
154 return factory == null ? defaultRowSetFactory() : factory;
155 }
156
157 private static RowSetFactory defaultRowSetFactory() {
158 return new com.sun.rowset.RowSetFactoryImpl();
159 }
160
161 /**
162 * <p>Creates a new instance of a <code>RowSetFactory</code> from the
163 * specified factory class name.
164 * This function is useful when there are multiple providers in the classpath.
165 * It gives more control to the application as it can specify which provider
166 * should be loaded.</p>
167 *
168 * <p>Once an application has obtained a reference to a <code>RowSetFactory</code>
169 * it can use the factory to obtain RowSet instances.</p>
170 *
171 * @param factoryClassName fully qualified factory class name that
172 * provides an implementation of <code>javax.sql.rowset.RowSetFactory</code>.
173 *
174 * @param cl <code>ClassLoader</code> used to load the factory
175 * class. If <code>null</code> current <code>Thread</code>'s context
176 * classLoader is used to load the factory class.
177 *
178 * @return New instance of a <code>RowSetFactory</code>
179 *
180 * @throws SQLException if <code>factoryClassName</code> is
181 * <code>null</code>, or the factory class cannot be loaded, instantiated.
182 *
183 * @see #newFactory()
184 *
185 * @since 1.7
186 */
187 public static RowSetFactory newFactory(String factoryClassName, ClassLoader cl)
188 throws SQLException {
189
190 trace("***In newInstance()");
191
192 if(factoryClassName == null) {
193 throw new SQLException("Error: factoryClassName cannot be null");
194 }
195 try {
196 ReflectUtil.checkPackageAccess(factoryClassName);
197 } catch (java.security.AccessControlException e) {
198 throw new SQLException("Access Exception",e);
199 }
200
201 try {
202 // getFactoryClass takes care of adding the read edge if
203 // necessary
204 Class<?> providerClass = getFactoryClass(factoryClassName, cl, false);
205 RowSetFactory instance = (RowSetFactory) providerClass.newInstance();
206 if (debug) {
207 trace("Created new instance of " + providerClass +
208 " using ClassLoader: " + cl);
209 }
210 return instance;
211 } catch (ClassNotFoundException x) {
212 throw new SQLException(
213 "Provider " + factoryClassName + " not found", x);
214 } catch (Exception x) {
215 throw new SQLException(
216 "Provider " + factoryClassName + " could not be instantiated: " + x,
217 x);
218 }
219 }
220
221 /*
222 * Returns the class loader to be used.
223 * @return The ClassLoader to use.
224 *
225 */
226 static private ClassLoader getContextClassLoader() throws SecurityException {
227 return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
228
229 public ClassLoader run() {
230 ClassLoader cl = null;
231
232 cl = Thread.currentThread().getContextClassLoader();
233
234 if (cl == null) {
235 cl = ClassLoader.getSystemClassLoader();
236 }
237
238 return cl;
239 }
240 });
241 }
242
243 /**
244 * Attempt to load a class using the class loader supplied. If that fails
245 * and fall back is enabled, the current (i.e. bootstrap) class loader is
246 * tried.
247 *
248 * If the class loader supplied is <code>null</code>, first try using the
249 * context class loader followed by the current class loader.
250 * @return The class which was loaded
251 */
252 static private Class<?> getFactoryClass(String factoryClassName, ClassLoader cl,
253 boolean doFallback) throws ClassNotFoundException {
254 Class<?> factoryClass = null;
255
256 try {
257 if (cl == null) {
258 cl = getContextClassLoader();
259 if (cl == null) {
260 throw new ClassNotFoundException();
261 } else {
262 factoryClass = cl.loadClass(factoryClassName);
263 }
264 } else {
265 factoryClass = cl.loadClass(factoryClassName);
266 }
267 } catch (ClassNotFoundException e) {
268 if (doFallback) {
269 // Use current class loader
270 factoryClass = Class.forName(factoryClassName, true, RowSetFactory.class.getClassLoader());
271 } else {
272 throw e;
273 }
274 }
275
276 ReflectUtil.checkPackageAccess(factoryClass);
277 return factoryClass;
278 }
279
280 /**
281 * Use the ServiceLoader mechanism to load the default RowSetFactory
282 * @return default RowSetFactory Implementation
283 */
284 static private RowSetFactory loadViaServiceLoader() throws SQLException {
285 RowSetFactory theFactory = null;
286 try {
287 trace("***in loadViaServiceLoader():");
288 for (RowSetFactory factory : ServiceLoader.load(javax.sql.rowset.RowSetFactory.class)) {
289 trace(" Loading done by the java.util.ServiceLoader :" + factory.getClass().getName());
290 theFactory = factory;
291 break;
292 }
293 } catch (ServiceConfigurationError e) {
294 throw new SQLException(
295 "RowSetFactory: Error locating RowSetFactory using Service "
296 + "Loader API: " + e, e);
297 }
298 return theFactory;
299
300 }
301
302 /**
303 * Returns the requested System Property. If a {@code SecurityException}
304 * occurs, just return NULL
305 * @param propName - System property to retrieve
306 * @return The System property value or NULL if the property does not exist
307 * or a {@code SecurityException} occurs.
308 */
309 static private String getSystemProperty(final String propName) {
310 String property = null;
311 try {
312 property = AccessController.doPrivileged(new PrivilegedAction<String>() {
313
314 public String run() {
315 return System.getProperty(propName);
316 }
317 }, null, new PropertyPermission(propName, "read"));
318 } catch (SecurityException se) {
319 trace("error getting " + propName + ": "+ se);
320 if (debug) {
321 se.printStackTrace();
322 }
323 }
324 return property;
325 }
326
327 /**
328 * Debug routine which will output tracing if the System Property
329 * -Djavax.sql.rowset.RowSetFactory.debug is set
330 * @param msg - The debug message to display
331 */
332 private static void trace(String msg) {
333 if (debug) {
334 System.err.println("###RowSets: " + msg);
335 }
336 }
337 }