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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 | } | ||