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