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| 1 | /* | ||
| 2 | * Copyright (c) 1996, 2004, 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 java.rmi.server; | ||
| 27 | |||
| 28 | import java.net.MalformedURLException; | ||
| 29 | import java.net.URL; | ||
| 30 | import java.security.AccessController; | ||
| 31 | import java.security.PrivilegedAction; | ||
| 32 | import java.util.Iterator; | ||
| 33 | import java.util.ServiceLoader; | ||
| 34 | |||
| 35 | /** | ||
| 36 | * <code>RMIClassLoader</code> comprises static methods to support | ||
| 37 | * dynamic class loading with RMI. Included are methods for loading | ||
| 38 | * classes from a network location (one or more URLs) and obtaining | ||
| 39 | * the location from which an existing class should be loaded by | ||
| 40 | * remote parties. These methods are used by the RMI runtime when | ||
| 41 | * marshalling and unmarshalling classes contained in the arguments | ||
| 42 | * and return values of remote method calls, and they also may be | ||
| 43 | * invoked directly by applications in order to mimic RMI's dynamic | ||
| 44 | * class loading behavior. | ||
| 45 | * | ||
| 46 | * <p>The implementation of the following static methods | ||
| 47 | * | ||
| 48 | * <ul> | ||
| 49 | * | ||
| 50 | * <li>{@link #loadClass(URL,String)} | ||
| 51 | * <li>{@link #loadClass(String,String)} | ||
| 52 | * <li>{@link #loadClass(String,String,ClassLoader)} | ||
| 53 | * <li>{@link #loadProxyClass(String,String[],ClassLoader)} | ||
| 54 | * <li>{@link #getClassLoader(String)} | ||
| 55 | * <li>{@link #getClassAnnotation(Class)} | ||
| 56 | * | ||
| 57 | * </ul> | ||
| 58 | * | ||
| 59 | * is provided by an instance of {@link RMIClassLoaderSpi}, the | ||
| 60 | * service provider interface for those methods. When one of the | ||
| 61 | * methods is invoked, its behavior is to delegate to a corresponding | ||
| 62 | * method on the service provider instance. The details of how each | ||
| 63 | * method delegates to the provider instance is described in the | ||
| 64 | * documentation for each particular method. | ||
| 65 | * | ||
| 66 | * <p>The service provider instance is chosen as follows: | ||
| 67 | * | ||
| 68 | * <ul> | ||
| 69 | * | ||
| 70 | * <li>If the system property | ||
| 71 | * <code>java.rmi.server.RMIClassLoaderSpi</code> is defined, then if | ||
| 72 | * its value equals the string <code>"default"</code>, the provider | ||
| 73 | * instance will be the value returned by an invocation of the {@link | ||
| 74 | * #getDefaultProviderInstance()} method, and for any other value, if | ||
| 75 | * a class named with the value of the property can be loaded by the | ||
| 76 | * system class loader (see {@link ClassLoader#getSystemClassLoader}) | ||
| 77 | * and that class is assignable to {@link RMIClassLoaderSpi} and has a | ||
| 78 | * public no-argument constructor, then that constructor will be | ||
| 79 | * invoked to create the provider instance. If the property is | ||
| 80 | * defined but any other of those conditions are not true, then an | ||
| 81 | * unspecified <code>Error</code> will be thrown to code that attempts | ||
| 82 | * to use <code>RMIClassLoader</code>, indicating the failure to | ||
| 83 | * obtain a provider instance. | ||
| 84 | * | ||
| 85 | * <li>If a resource named | ||
| 86 | * <code>META-INF/services/java.rmi.server.RMIClassLoaderSpi</code> is | ||
| 87 | * visible to the system class loader, then the contents of that | ||
| 88 | * resource are interpreted as a provider-configuration file, and the | ||
| 89 | * first class name specified in that file is used as the provider | ||
| 90 | * class name. If a class with that name can be loaded by the system | ||
| 91 | * class loader and that class is assignable to {@link | ||
| 92 | * RMIClassLoaderSpi} and has a public no-argument constructor, then | ||
| 93 | * that constructor will be invoked to create the provider instance. | ||
| 94 | * If the resource is found but a provider cannot be instantiated as | ||
| 95 | * described, then an unspecified <code>Error</code> will be thrown to | ||
| 96 | * code that attempts to use <code>RMIClassLoader</code>, indicating | ||
| 97 | * the failure to obtain a provider instance. | ||
| 98 | * | ||
| 99 | * <li>Otherwise, the provider instance will be the value returned by | ||
| 100 | * an invocation of the {@link #getDefaultProviderInstance()} method. | ||
| 101 | * | ||
| 102 | * </ul> | ||
| 103 | * | ||
| 104 | * @author Ann Wollrath | ||
| 105 | * @author Peter Jones | ||
| 106 | * @author Laird Dornin | ||
| 107 | * @see RMIClassLoaderSpi | ||
| 108 | * @since JDK1.1 | ||
| 109 | */ | ||
| 110 | public class RMIClassLoader { | ||
| 111 | |||
| 112 | /** "default" provider instance */ | ||
| 113 | private static final RMIClassLoaderSpi defaultProvider = | ||
| 114 | newDefaultProviderInstance(); | ||
| 115 | |||
| 116 | /** provider instance */ | ||
| 117 | private static final RMIClassLoaderSpi provider = | ||
| 118 | AccessController.doPrivileged( | ||
| 119 | new PrivilegedAction<RMIClassLoaderSpi>() { | ||
| 120 | public RMIClassLoaderSpi run() { return initializeProvider(); } | ||
| 121 | }); | ||
| 122 | |||
| 123 | /* | ||
| 124 | * Disallow anyone from creating one of these. | ||
| 125 | */ | ||
| 126 | private RMIClassLoader() {} | ||
| 127 | |||
| 128 | /** | ||
| 129 | * Loads the class with the specified <code>name</code>. | ||
| 130 | * | ||
| 131 | * <p>This method delegates to {@link #loadClass(String,String)}, | ||
| 132 | * passing <code>null</code> as the first argument and | ||
| 133 | * <code>name</code> as the second argument. | ||
| 134 | * | ||
| 135 | * @param name the name of the class to load | ||
| 136 | * | ||
| 137 | * @return the <code>Class</code> object representing the loaded class | ||
| 138 | * | ||
| 139 | * @throws MalformedURLException if a provider-specific URL used | ||
| 140 | * to load classes is invalid | ||
| 141 | * | ||
| 142 | * @throws ClassNotFoundException if a definition for the class | ||
| 143 | * could not be found at the codebase location | ||
| 144 | * | ||
| 145 | * @deprecated replaced by <code>loadClass(String,String)</code> method | ||
| 146 | * @see #loadClass(String,String) | ||
| 147 | */ | ||
| 148 | @Deprecated | ||
| 149 | public static Class<?> loadClass(String name) | ||
| 150 | throws MalformedURLException, ClassNotFoundException | ||
| 151 | { | ||
| 152 | return loadClass((String) null, name); | ||
| 153 | } | ||
| 154 | |||
| 155 | /** | ||
| 156 | * Loads a class from a codebase URL. | ||
| 157 | * | ||
| 158 | * If <code>codebase</code> is <code>null</code>, then this method | ||
| 159 | * will behave the same as {@link #loadClass(String,String)} with a | ||
| 160 | * <code>null</code> <code>codebase</code> and the given class name. | ||
| 161 | * | ||
| 162 | * <p>This method delegates to the | ||
| 163 | * {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} | ||
| 164 | * method of the provider instance, passing the result of invoking | ||
| 165 | * {@link URL#toString} on the given URL (or <code>null</code> if | ||
| 166 | * <code>codebase</code> is null) as the first argument, | ||
| 167 | * <code>name</code> as the second argument, | ||
| 168 | * and <code>null</code> as the third argument. | ||
| 169 | * | ||
| 170 | * @param codebase the URL to load the class from, or <code>null</code> | ||
| 171 | * | ||
| 172 | * @param name the name of the class to load | ||
| 173 | * | ||
| 174 | * @return the <code>Class</code> object representing the loaded class | ||
| 175 | * | ||
| 176 | * @throws MalformedURLException if <code>codebase</code> is | ||
| 177 | * <code>null</code> and a provider-specific URL used | ||
| 178 | * to load classes is invalid | ||
| 179 | * | ||
| 180 | * @throws ClassNotFoundException if a definition for the class | ||
| 181 | * could not be found at the specified URL | ||
| 182 | */ | ||
| 183 | public static Class<?> loadClass(URL codebase, String name) | ||
| 184 | throws MalformedURLException, ClassNotFoundException | ||
| 185 | { | ||
| 186 | return provider.loadClass( | ||
| 187 | codebase != null ? codebase.toString() : null, name, null); | ||
| 188 | } | ||
| 189 | |||
| 190 | /** | ||
| 191 | * Loads a class from a codebase URL path. | ||
| 192 | * | ||
| 193 | * <p>This method delegates to the | ||
| 194 | * {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} | ||
| 195 | * method of the provider instance, passing <code>codebase</code> | ||
| 196 | * as the first argument, <code>name</code> as the second argument, | ||
| 197 | * and <code>null</code> as the third argument. | ||
| 198 | * | ||
| 199 | * @param codebase the list of URLs (separated by spaces) to load | ||
| 200 | * the class from, or <code>null</code> | ||
| 201 | * | ||
| 202 | * @param name the name of the class to load | ||
| 203 | * | ||
| 204 | * @return the <code>Class</code> object representing the loaded class | ||
| 205 | * | ||
| 206 | * @throws MalformedURLException if <code>codebase</code> is | ||
| 207 | * non-<code>null</code> and contains an invalid URL, or if | ||
| 208 | * <code>codebase</code> is <code>null</code> and a provider-specific | ||
| 209 | * URL used to load classes is invalid | ||
| 210 | * | ||
| 211 | * @throws ClassNotFoundException if a definition for the class | ||
| 212 | * could not be found at the specified location | ||
| 213 | * | ||
| 214 | * @since 1.2 | ||
| 215 | */ | ||
| 216 | public static Class<?> loadClass(String codebase, String name) | ||
| 217 | throws MalformedURLException, ClassNotFoundException | ||
| 218 | { | ||
| 219 | return provider.loadClass(codebase, name, null); | ||
| 220 | } | ||
| 221 | |||
| 222 | /** | ||
| 223 | * Loads a class from a codebase URL path, optionally using the | ||
| 224 | * supplied loader. | ||
| 225 | * | ||
| 226 | * This method should be used when the caller would like to make | ||
| 227 | * available to the provider implementation an additional contextual | ||
| 228 | * class loader to consider, such as the loader of a caller on the | ||
| 229 | * stack. Typically, a provider implementation will attempt to | ||
| 230 | * resolve the named class using the given <code>defaultLoader</code>, | ||
| 231 | * if specified, before attempting to resolve the class from the | ||
| 232 | * codebase URL path. | ||
| 233 | * | ||
| 234 | * <p>This method delegates to the | ||
| 235 | * {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} | ||
| 236 | * method of the provider instance, passing <code>codebase</code> | ||
| 237 | * as the first argument, <code>name</code> as the second argument, | ||
| 238 | * and <code>defaultLoader</code> as the third argument. | ||
| 239 | * | ||
| 240 | * @param codebase the list of URLs (separated by spaces) to load | ||
| 241 | * the class from, or <code>null</code> | ||
| 242 | * | ||
| 243 | * @param name the name of the class to load | ||
| 244 | * | ||
| 245 | * @param defaultLoader additional contextual class loader | ||
| 246 | * to use, or <code>null</code> | ||
| 247 | * | ||
| 248 | * @return the <code>Class</code> object representing the loaded class | ||
| 249 | * | ||
| 250 | * @throws MalformedURLException if <code>codebase</code> is | ||
| 251 | * non-<code>null</code> and contains an invalid URL, or if | ||
| 252 | * <code>codebase</code> is <code>null</code> and a provider-specific | ||
| 253 | * URL used to load classes is invalid | ||
| 254 | * | ||
| 255 | * @throws ClassNotFoundException if a definition for the class | ||
| 256 | * could not be found at the specified location | ||
| 257 | * | ||
| 258 | * @since 1.4 | ||
| 259 | */ | ||
| 260 | public static Class<?> loadClass(String codebase, String name, | ||
| 261 | ClassLoader defaultLoader) | ||
| 262 | throws MalformedURLException, ClassNotFoundException | ||
| 263 | { | ||
| 264 | return provider.loadClass(codebase, name, defaultLoader); | ||
| 265 | } | ||
| 266 | |||
| 267 | /** | ||
| 268 | * Loads a dynamic proxy class (see {@link java.lang.reflect.Proxy}) | ||
| 269 | * that implements a set of interfaces with the given names | ||
| 270 | * from a codebase URL path. | ||
| 271 | * | ||
| 272 | * <p>The interfaces will be resolved similar to classes loaded via | ||
| 273 | * the {@link #loadClass(String,String)} method using the given | ||
| 274 | * <code>codebase</code>. | ||
| 275 | * | ||
| 276 | * <p>This method delegates to the | ||
| 277 | * {@link RMIClassLoaderSpi#loadProxyClass(String,String[],ClassLoader)} | ||
| 278 | * method of the provider instance, passing <code>codebase</code> | ||
| 279 | * as the first argument, <code>interfaces</code> as the second argument, | ||
| 280 | * and <code>defaultLoader</code> as the third argument. | ||
| 281 | * | ||
| 282 | * @param codebase the list of URLs (space-separated) to load | ||
| 283 | * classes from, or <code>null</code> | ||
| 284 | * | ||
| 285 | * @param interfaces the names of the interfaces for the proxy class | ||
| 286 | * to implement | ||
| 287 | * | ||
| 288 | * @param defaultLoader additional contextual class loader | ||
| 289 | * to use, or <code>null</code> | ||
| 290 | * | ||
| 291 | * @return a dynamic proxy class that implements the named interfaces | ||
| 292 | * | ||
| 293 | * @throws MalformedURLException if <code>codebase</code> is | ||
| 294 | * non-<code>null</code> and contains an invalid URL, or | ||
| 295 | * if <code>codebase</code> is <code>null</code> and a provider-specific | ||
| 296 | * URL used to load classes is invalid | ||
| 297 | * | ||
| 298 | * @throws ClassNotFoundException if a definition for one of | ||
| 299 | * the named interfaces could not be found at the specified location, | ||
| 300 | * or if creation of the dynamic proxy class failed (such as if | ||
| 301 | * {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[])} | ||
| 302 | * would throw an <code>IllegalArgumentException</code> for the given | ||
| 303 | * interface list) | ||
| 304 | * | ||
| 305 | * @since 1.4 | ||
| 306 | */ | ||
| 307 | public static Class<?> loadProxyClass(String codebase, String[] interfaces, | ||
| 308 | ClassLoader defaultLoader) | ||
| 309 | throws ClassNotFoundException, MalformedURLException | ||
| 310 | { | ||
| 311 | return provider.loadProxyClass(codebase, interfaces, defaultLoader); | ||
| 312 | } | ||
| 313 | |||
| 314 | /** | ||
| 315 | * Returns a class loader that loads classes from the given codebase | ||
| 316 | * URL path. | ||
| 317 | * | ||
| 318 | * <p>The class loader returned is the class loader that the | ||
| 319 | * {@link #loadClass(String,String)} method would use to load classes | ||
| 320 | * for the same <code>codebase</code> argument. | ||
| 321 | * | ||
| 322 | * <p>This method delegates to the | ||
| 323 | * {@link RMIClassLoaderSpi#getClassLoader(String)} method | ||
| 324 | * of the provider instance, passing <code>codebase</code> as the argument. | ||
| 325 | * | ||
| 326 | * <p>If there is a security manger, its <code>checkPermission</code> | ||
| 327 | * method will be invoked with a | ||
| 328 | * <code>RuntimePermission("getClassLoader")</code> permission; | ||
| 329 | * this could result in a <code>SecurityException</code>. | ||
| 330 | * The provider implementation of this method may also perform further | ||
| 331 | * security checks to verify that the calling context has permission to | ||
| 332 | * connect to all of the URLs in the codebase URL path. | ||
| 333 | * | ||
| 334 | * @param codebase the list of URLs (space-separated) from which | ||
| 335 | * the returned class loader will load classes from, or <code>null</code> | ||
| 336 | * | ||
| 337 | * @return a class loader that loads classes from the given codebase URL | ||
| 338 | * path | ||
| 339 | * | ||
| 340 | * @throws MalformedURLException if <code>codebase</code> is | ||
| 341 | * non-<code>null</code> and contains an invalid URL, or | ||
| 342 | * if <code>codebase</code> is <code>null</code> and a provider-specific | ||
| 343 | * URL used to identify the class loader is invalid | ||
| 344 | * | ||
| 345 | * @throws SecurityException if there is a security manager and the | ||
| 346 | * invocation of its <code>checkPermission</code> method fails, or | ||
| 347 | * if the caller does not have permission to connect to all of the | ||
| 348 | * URLs in the codebase URL path | ||
| 349 | * | ||
| 350 | * @since 1.3 | ||
| 351 | */ | ||
| 352 | public static ClassLoader getClassLoader(String codebase) | ||
| 353 | throws MalformedURLException, SecurityException | ||
| 354 | { | ||
| 355 | return provider.getClassLoader(codebase); | ||
| 356 | } | ||
| 357 | |||
| 358 | /** | ||
| 359 | * Returns the annotation string (representing a location for | ||
| 360 | * the class definition) that RMI will use to annotate the class | ||
| 361 | * descriptor when marshalling objects of the given class. | ||
| 362 | * | ||
| 363 | * <p>This method delegates to the | ||
| 364 | * {@link RMIClassLoaderSpi#getClassAnnotation(Class)} method | ||
| 365 | * of the provider instance, passing <code>cl</code> as the argument. | ||
| 366 | * | ||
| 367 | * @param cl the class to obtain the annotation for | ||
| 368 | * | ||
| 369 | * @return a string to be used to annotate the given class when | ||
| 370 | * it gets marshalled, or <code>null</code> | ||
| 371 | * | ||
| 372 | * @throws NullPointerException if <code>cl</code> is <code>null</code> | ||
| 373 | * | ||
| 374 | * @since 1.2 | ||
| 375 | */ | ||
| 376 | /* | ||
| 377 | * REMIND: Should we say that the returned class annotation will or | ||
| 378 | * should be a (space-separated) list of URLs? | ||
| 379 | */ | ||
| 380 | public static String getClassAnnotation(Class<?> cl) { | ||
| 381 | return provider.getClassAnnotation(cl); | ||
| 382 | } | ||
| 383 | |||
| 384 | /** | ||
| 385 | * Returns the canonical instance of the default provider | ||
| 386 | * for the service provider interface {@link RMIClassLoaderSpi}. | ||
| 387 | * If the system property <code>java.rmi.server.RMIClassLoaderSpi</code> | ||
| 388 | * is not defined, then the <code>RMIClassLoader</code> static | ||
| 389 | * methods | ||
| 390 | * | ||
| 391 | * <ul> | ||
| 392 | * | ||
| 393 | * <li>{@link #loadClass(URL,String)} | ||
| 394 | * <li>{@link #loadClass(String,String)} | ||
| 395 | * <li>{@link #loadClass(String,String,ClassLoader)} | ||
| 396 | * <li>{@link #loadProxyClass(String,String[],ClassLoader)} | ||
| 397 | * <li>{@link #getClassLoader(String)} | ||
| 398 | * <li>{@link #getClassAnnotation(Class)} | ||
| 399 | * | ||
| 400 | * </ul> | ||
| 401 | * | ||
| 402 | * will use the canonical instance of the default provider | ||
| 403 | * as the service provider instance. | ||
| 404 | * | ||
| 405 | * <p>If there is a security manager, its | ||
| 406 | * <code>checkPermission</code> method will be invoked with a | ||
| 407 | * <code>RuntimePermission("setFactory")</code> permission; this | ||
| 408 | * could result in a <code>SecurityException</code>. | ||
| 409 | * | ||
| 410 | * <p>The default service provider instance implements | ||
| 411 | * {@link RMIClassLoaderSpi} as follows: | ||
| 412 | * | ||
| 413 | * <blockquote> | ||
| 414 | * | ||
| 415 | * <p>The <b>{@link RMIClassLoaderSpi#getClassAnnotation(Class) | ||
| 416 | * getClassAnnotation}</b> method returns a <code>String</code> | ||
| 417 | * representing the codebase URL path that a remote party should | ||
| 418 | * use to download the definition for the specified class. The | ||
| 419 | * format of the returned string is a path of URLs separated by | ||
| 420 | * spaces. | ||
| 421 | * | ||
| 422 | * The codebase string returned depends on the defining class | ||
| 423 | * loader of the specified class: | ||
| 424 | * | ||
| 425 | * <ul> | ||
| 426 | * | ||
| 427 | * <p><li>If the class loader is the system class loader (see | ||
| 428 | * {@link ClassLoader#getSystemClassLoader}), a parent of the | ||
| 429 | * system class loader such as the loader used for installed | ||
| 430 | * extensions, or the bootstrap class loader (which may be | ||
| 431 | * represented by <code>null</code>), then the value of the | ||
| 432 | * <code>java.rmi.server.codebase</code> property (or possibly an | ||
| 433 | * earlier cached value) is returned, or | ||
| 434 | * <code>null</code> is returned if that property is not set. | ||
| 435 | * | ||
| 436 | * <p><li>Otherwise, if the class loader is an instance of | ||
| 437 | * <code>URLClassLoader</code>, then the returned string is a | ||
| 438 | * space-separated list of the external forms of the URLs returned | ||
| 439 | * by invoking the <code>getURLs</code> methods of the loader. If | ||
| 440 | * the <code>URLClassLoader</code> was created by this provider to | ||
| 441 | * service an invocation of its <code>loadClass</code> or | ||
| 442 | * <code>loadProxyClass</code> methods, then no permissions are | ||
| 443 | * required to get the associated codebase string. If it is an | ||
| 444 | * arbitrary other <code>URLClassLoader</code> instance, then if | ||
| 445 | * there is a security manager, its <code>checkPermission</code> | ||
| 446 | * method will be invoked once for each URL returned by the | ||
| 447 | * <code>getURLs</code> method, with the permission returned by | ||
| 448 | * invoking <code>openConnection().getPermission()</code> on each | ||
| 449 | * URL; if any of those invocations throws a | ||
| 450 | * <code>SecurityException</code> or an <code>IOException</code>, | ||
| 451 | * then the value of the <code>java.rmi.server.codebase</code> | ||
| 452 | * property (or possibly an earlier cached value) is returned, or | ||
| 453 | * <code>null</code> is returned if that property is not set. | ||
| 454 | * | ||
| 455 | * <p><li>Finally, if the class loader is not an instance of | ||
| 456 | * <code>URLClassLoader</code>, then the value of the | ||
| 457 | * <code>java.rmi.server.codebase</code> property (or possibly an | ||
| 458 | * earlier cached value) is returned, or | ||
| 459 | * <code>null</code> is returned if that property is not set. | ||
| 460 | * | ||
| 461 | * </ul> | ||
| 462 | * | ||
| 463 | * <p>For the implementations of the methods described below, | ||
| 464 | * which all take a <code>String</code> parameter named | ||
| 465 | * <code>codebase</code> that is a space-separated list of URLs, | ||
| 466 | * each invocation has an associated <i>codebase loader</i> that | ||
| 467 | * is identified using the <code>codebase</code> argument in | ||
| 468 | * conjunction with the current thread's context class loader (see | ||
| 469 | * {@link Thread#getContextClassLoader()}). When there is a | ||
| 470 | * security manager, this provider maintains an internal table of | ||
| 471 | * class loader instances (which are at least instances of {@link | ||
| 472 | * java.net.URLClassLoader}) keyed by the pair of their parent | ||
| 473 | * class loader and their codebase URL path (an ordered list of | ||
| 474 | * URLs). If the <code>codebase</code> argument is <code>null</code>, | ||
| 475 | * the codebase URL path is the value of the system property | ||
| 476 | * <code>java.rmi.server.codebase</code> or possibly an | ||
| 477 | * earlier cached value. For a given codebase URL path passed as the | ||
| 478 | * <code>codebase</code> argument to an invocation of one of the | ||
| 479 | * below methods in a given context, the codebase loader is the | ||
| 480 | * loader in the table with the specified codebase URL path and | ||
| 481 | * the current thread's context class loader as its parent. If no | ||
| 482 | * such loader exists, then one is created and added to the table. | ||
| 483 | * The table does not maintain strong references to its contained | ||
| 484 | * loaders, in order to allow them and their defined classes to be | ||
| 485 | * garbage collected when not otherwise reachable. In order to | ||
| 486 | * prevent arbitrary untrusted code from being implicitly loaded | ||
| 487 | * into a virtual machine with no security manager, if there is no | ||
| 488 | * security manager set, the codebase loader is just the current | ||
| 489 | * thread's context class loader (the supplied codebase URL path | ||
| 490 | * is ignored, so remote class loading is disabled). | ||
| 491 | * | ||
| 492 | * <p>The <b>{@link RMIClassLoaderSpi#getClassLoader(String) | ||
| 493 | * getClassLoader}</b> method returns the codebase loader for the | ||
| 494 | * specified codebase URL path. If there is a security manager, | ||
| 495 | * then if the calling context does not have permission to connect | ||
| 496 | * to all of the URLs in the codebase URL path, a | ||
| 497 | * <code>SecurityException</code> will be thrown. | ||
| 498 | * | ||
| 499 | * <p>The <b>{@link | ||
| 500 | * RMIClassLoaderSpi#loadClass(String,String,ClassLoader) | ||
| 501 | * loadClass}</b> method attempts to load the class with the | ||
| 502 | * specified name as follows: | ||
| 503 | * | ||
| 504 | * <blockquote> | ||
| 505 | * | ||
| 506 | * If the <code>defaultLoader</code> argument is | ||
| 507 | * non-<code>null</code>, it first attempts to load the class with the | ||
| 508 | * specified <code>name</code> using the | ||
| 509 | * <code>defaultLoader</code>, such as by evaluating | ||
| 510 | * | ||
| 511 | * <pre> | ||
| 512 | * Class.forName(name, false, defaultLoader) | ||
| 513 | * </pre> | ||
| 514 | * | ||
| 515 | * If the class is successfully loaded from the | ||
| 516 | * <code>defaultLoader</code>, that class is returned. If an | ||
| 517 | * exception other than <code>ClassNotFoundException</code> is | ||
| 518 | * thrown, that exception is thrown to the caller. | ||
| 519 | * | ||
| 520 | * <p>Next, the <code>loadClass</code> method attempts to load the | ||
| 521 | * class with the specified <code>name</code> using the codebase | ||
| 522 | * loader for the specified codebase URL path. | ||
| 523 | * If there is a security manager, then the calling context | ||
| 524 | * must have permission to connect to all of the URLs in the | ||
| 525 | * codebase URL path; otherwise, the current thread's context | ||
| 526 | * class loader will be used instead of the codebase loader. | ||
| 527 | * | ||
| 528 | * </blockquote> | ||
| 529 | * | ||
| 530 | * <p>The <b>{@link | ||
| 531 | * RMIClassLoaderSpi#loadProxyClass(String,String[],ClassLoader) | ||
| 532 | * loadProxyClass}</b> method attempts to return a dynamic proxy | ||
| 533 | * class with the named interface as follows: | ||
| 534 | * | ||
| 535 | * <blockquote> | ||
| 536 | * | ||
| 537 | * <p>If the <code>defaultLoader</code> argument is | ||
| 538 | * non-<code>null</code> and all of the named interfaces can be | ||
| 539 | * resolved through that loader, then, | ||
| 540 | * | ||
| 541 | * <ul> | ||
| 542 | * | ||
| 543 | * <li>if all of the resolved interfaces are <code>public</code>, | ||
| 544 | * then it first attempts to obtain a dynamic proxy class (using | ||
| 545 | * {@link | ||
| 546 | * java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[]) | ||
| 547 | * Proxy.getProxyClass}) for the resolved interfaces defined in | ||
| 548 | * the codebase loader; if that attempt throws an | ||
| 549 | * <code>IllegalArgumentException</code>, it then attempts to | ||
| 550 | * obtain a dynamic proxy class for the resolved interfaces | ||
| 551 | * defined in the <code>defaultLoader</code>. If both attempts | ||
| 552 | * throw <code>IllegalArgumentException</code>, then this method | ||
| 553 | * throws a <code>ClassNotFoundException</code>. If any other | ||
| 554 | * exception is thrown, that exception is thrown to the caller. | ||
| 555 | * | ||
| 556 | * <li>if all of the non-<code>public</code> resolved interfaces | ||
| 557 | * are defined in the same class loader, then it attempts to | ||
| 558 | * obtain a dynamic proxy class for the resolved interfaces | ||
| 559 | * defined in that loader. | ||
| 560 | * | ||
| 561 | * <li>otherwise, a <code>LinkageError</code> is thrown (because a | ||
| 562 | * class that implements all of the specified interfaces cannot be | ||
| 563 | * defined in any loader). | ||
| 564 | * | ||
| 565 | * </ul> | ||
| 566 | * | ||
| 567 | * <p>Otherwise, if all of the named interfaces can be resolved | ||
| 568 | * through the codebase loader, then, | ||
| 569 | * | ||
| 570 | * <ul> | ||
| 571 | * | ||
| 572 | * <li>if all of the resolved interfaces are <code>public</code>, | ||
| 573 | * then it attempts to obtain a dynamic proxy class for the | ||
| 574 | * resolved interfaces in the codebase loader. If the attempt | ||
| 575 | * throws an <code>IllegalArgumentException</code>, then this | ||
| 576 | * method throws a <code>ClassNotFoundException</code>. | ||
| 577 | * | ||
| 578 | * <li>if all of the non-<code>public</code> resolved interfaces | ||
| 579 | * are defined in the same class loader, then it attempts to | ||
| 580 | * obtain a dynamic proxy class for the resolved interfaces | ||
| 581 | * defined in that loader. | ||
| 582 | * | ||
| 583 | * <li>otherwise, a <code>LinkageError</code> is thrown (because a | ||
| 584 | * class that implements all of the specified interfaces cannot be | ||
| 585 | * defined in any loader). | ||
| 586 | * | ||
| 587 | * </ul> | ||
| 588 | * | ||
| 589 | * <p>Otherwise, a <code>ClassNotFoundException</code> is thrown | ||
| 590 | * for one of the named interfaces that could not be resolved. | ||
| 591 | * | ||
| 592 | * </blockquote> | ||
| 593 | * | ||
| 594 | * </blockquote> | ||
| 595 | * | ||
| 596 | * @return the canonical instance of the default service provider | ||
| 597 | * | ||
| 598 | * @throws SecurityException if there is a security manager and the | ||
| 599 | * invocation of its <code>checkPermission</code> method fails | ||
| 600 | * | ||
| 601 | * @since 1.4 | ||
| 602 | */ | ||
| 603 | public static RMIClassLoaderSpi getDefaultProviderInstance() { | ||
| 604 | SecurityManager sm = System.getSecurityManager(); | ||
| 605 | if (sm != null) { | ||
| 606 | sm.checkPermission(new RuntimePermission("setFactory")); | ||
| 607 | } | ||
| 608 | return defaultProvider; | ||
| 609 | } | ||
| 610 | |||
| 611 | /** | ||
| 612 | * Returns the security context of the given class loader. | ||
| 613 | * | ||
| 614 | * @param loader a class loader from which to get the security context | ||
| 615 | * | ||
| 616 | * @return the security context | ||
| 617 | * | ||
| 618 | * @deprecated no replacement. As of the Java 2 platform v1.2, RMI no | ||
| 619 | * longer uses this method to obtain a class loader's security context. | ||
| 620 | * @see java.lang.SecurityManager#getSecurityContext() | ||
| 621 | */ | ||
| 622 | @Deprecated | ||
| 623 | public static Object getSecurityContext(ClassLoader loader) | ||
| 624 | { | ||
| 625 | return sun.rmi.server.LoaderHandler.getSecurityContext(loader); | ||
| 626 | } | ||
| 627 | |||
| 628 | /** | ||
| 629 | * Creates an instance of the default provider class. | ||
| 630 | */ | ||
| 631 | private static RMIClassLoaderSpi newDefaultProviderInstance() { | ||
| 632 | return new RMIClassLoaderSpi() { | ||
| 633 | public Class<?> loadClass(String codebase, String name, | ||
| 634 | ClassLoader defaultLoader) | ||
| 635 | throws MalformedURLException, ClassNotFoundException | ||
| 636 | { | ||
| 637 | return sun.rmi.server.LoaderHandler.loadClass( | ||
| 638 | codebase, name, defaultLoader); | ||
| 639 | } | ||
| 640 | |||
| 641 | public Class<?> loadProxyClass(String codebase, | ||
| 642 | String[] interfaces, | ||
| 643 | ClassLoader defaultLoader) | ||
| 644 | throws MalformedURLException, ClassNotFoundException | ||
| 645 | { | ||
| 646 | return sun.rmi.server.LoaderHandler.loadProxyClass( | ||
| 647 | codebase, interfaces, defaultLoader); | ||
| 648 | } | ||
| 649 | |||
| 650 | public ClassLoader getClassLoader(String codebase) | ||
| 651 | throws MalformedURLException | ||
| 652 | { | ||
| 653 | return sun.rmi.server.LoaderHandler.getClassLoader(codebase); | ||
| 654 | } | ||
| 655 | |||
| 656 | public String getClassAnnotation(Class<?> cl) { | ||
| 657 | return sun.rmi.server.LoaderHandler.getClassAnnotation(cl); | ||
| 658 | } | ||
| 659 | }; | ||
| 660 | } | ||
| 661 | |||
| 662 | /** | ||
| 663 | * Chooses provider instance, following above documentation. | ||
| 664 | * | ||
| 665 | * This method assumes that it has been invoked in a privileged block. | ||
| 666 | */ | ||
| 667 | private static RMIClassLoaderSpi initializeProvider() { | ||
| 668 | /* | ||
| 669 | * First check for the system property being set: | ||
| 670 | */ | ||
| 671 | String providerClassName = | ||
| 672 | System.getProperty("java.rmi.server.RMIClassLoaderSpi"); | ||
| 673 | |||
| 674 | if (providerClassName != null) { | ||
| 675 | if (providerClassName.equals("default")) { | ||
| 676 | return defaultProvider; | ||
| 677 | } | ||
| 678 | |||
| 679 | try { | ||
| 680 | Class<? extends RMIClassLoaderSpi> providerClass = | ||
| 681 | Class.forName(providerClassName, false, | ||
| 682 | ClassLoader.getSystemClassLoader()) | ||
| 683 | .asSubclass(RMIClassLoaderSpi.class); | ||
| 684 | return providerClass.newInstance(); | ||
| 685 | |||
| 686 | } catch (ClassNotFoundException e) { | ||
| 687 | throw new NoClassDefFoundError(e.getMessage()); | ||
| 688 | } catch (IllegalAccessException e) { | ||
| 689 | throw new IllegalAccessError(e.getMessage()); | ||
| 690 | } catch (InstantiationException e) { | ||
| 691 | throw new InstantiationError(e.getMessage()); | ||
| 692 | } catch (ClassCastException e) { | ||
| 693 | Error error = new LinkageError( | ||
| 694 | "provider class not assignable to RMIClassLoaderSpi"); | ||
| 695 | error.initCause(e); | ||
| 696 | throw error; | ||
| 697 | } | ||
| 698 | } | ||
| 699 | |||
| 700 | /* | ||
| 701 | * Next look for a provider configuration file installed: | ||
| 702 | */ | ||
| 703 | Iterator<RMIClassLoaderSpi> iter = | ||
| 704 | ServiceLoader.load(RMIClassLoaderSpi.class, | ||
| 705 | ClassLoader.getSystemClassLoader()).iterator(); | ||
| 706 | if (iter.hasNext()) { | ||
| 707 | try { | ||
| 708 | return iter.next(); | ||
| 709 | } catch (ClassCastException e) { | ||
| 710 | Error error = new LinkageError( | ||
| 711 | "provider class not assignable to RMIClassLoaderSpi"); | ||
| 712 | error.initCause(e); | ||
| 713 | throw error; | ||
| 714 | } | ||
| 715 | } | ||
| 716 | |||
| 717 | /* | ||
| 718 | * Finally, return the canonical instance of the default provider. | ||
| 719 | */ | ||
| 720 | return defaultProvider; | ||
| 721 | } | ||
| 722 | } | ||