J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2005-2006 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package javax.script; |
| 27 | import java.util.*; |
| 28 | import java.net.URL; |
| 29 | import java.io.*; |
| 30 | import java.security.*; |
| 31 | import sun.misc.Service; |
| 32 | import sun.misc.ServiceConfigurationError; |
| 33 | import sun.reflect.Reflection; |
| 34 | import sun.security.util.SecurityConstants; |
| 35 | |
| 36 | /** |
| 37 | * The <code>ScriptEngineManager</code> implements a discovery and instantiation |
| 38 | * mechanism for <code>ScriptEngine</code> classes and also maintains a |
| 39 | * collection of key/value pairs storing state shared by all engines created |
| 40 | * by the Manager. This class uses the <a href="../../../technotes/guides/jar/jar.html#Service%20Provider">service provider</a> mechanism to enumerate all the |
| 41 | * implementations of <code>ScriptEngineFactory</code>. <br><br> |
| 42 | * The <code>ScriptEngineManager</code> provides a method to return an array of all these factories |
| 43 | * as well as utility methods which look up factories on the basis of language name, file extension |
| 44 | * and mime type. |
| 45 | * <p> |
| 46 | * The <code>Bindings</code> of key/value pairs, referred to as the "Global Scope" maintained |
| 47 | * by the manager is available to all instances of <code>ScriptEngine</code> created |
| 48 | * by the <code>ScriptEngineManager</code>. The values in the <code>Bindings</code> are |
| 49 | * generally exposed in all scripts. |
| 50 | * |
| 51 | * @author Mike Grogan |
| 52 | * @author A. Sundararajan |
| 53 | * @since 1.6 |
| 54 | */ |
| 55 | public class ScriptEngineManager { |
| 56 | private static final boolean DEBUG = false; |
| 57 | /** |
| 58 | * If the thread context ClassLoader can be accessed by the caller, |
| 59 | * then the effect of calling this constructor is the same as calling |
| 60 | * <code>ScriptEngineManager(Thread.currentThread().getContextClassLoader())</code>. |
| 61 | * Otherwise, the effect is the same as calling <code>ScriptEngineManager(null)</code>. |
| 62 | * |
| 63 | * @see java.lang.Thread#getContextClassLoader |
| 64 | */ |
| 65 | public ScriptEngineManager() { |
| 66 | ClassLoader ctxtLoader = Thread.currentThread().getContextClassLoader(); |
| 67 | if (canCallerAccessLoader(ctxtLoader)) { |
| 68 | if (DEBUG) System.out.println("using " + ctxtLoader); |
| 69 | init(ctxtLoader); |
| 70 | } else { |
| 71 | if (DEBUG) System.out.println("using bootstrap loader"); |
| 72 | init(null); |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * This constructor loads the implementations of |
| 78 | * <code>ScriptEngineFactory</code> visible to the given |
| 79 | * <code>ClassLoader</code> using the <a href="../../../technotes/guides/jar/jar.html#Service%20Provider">service provider</a> mechanism.<br><br> |
| 80 | * If loader is <code>null</code>, the script engine factories that are |
| 81 | * bundled with the platform and that are in the usual extension |
| 82 | * directories (installed extensions) are loaded. <br><br> |
| 83 | * |
| 84 | * @param loader ClassLoader used to discover script engine factories. |
| 85 | */ |
| 86 | public ScriptEngineManager(ClassLoader loader) { |
| 87 | init(loader); |
| 88 | } |
| 89 | |
| 90 | private void init(final ClassLoader loader) { |
| 91 | globalScope = new SimpleBindings(); |
| 92 | engineSpis = new HashSet<ScriptEngineFactory>(); |
| 93 | nameAssociations = new HashMap<String, ScriptEngineFactory>(); |
| 94 | extensionAssociations = new HashMap<String, ScriptEngineFactory>(); |
| 95 | mimeTypeAssociations = new HashMap<String, ScriptEngineFactory>(); |
| 96 | AccessController.doPrivileged(new PrivilegedAction<Object>() { |
| 97 | public Object run() { |
| 98 | initEngines(loader); |
| 99 | return null; |
| 100 | } |
| 101 | }); |
| 102 | } |
| 103 | |
| 104 | private void initEngines(final ClassLoader loader) { |
| 105 | Iterator itr = null; |
| 106 | try { |
| 107 | if (loader != null) { |
| 108 | itr = Service.providers(ScriptEngineFactory.class, loader); |
| 109 | } else { |
| 110 | itr = Service.installedProviders(ScriptEngineFactory.class); |
| 111 | } |
| 112 | } catch (ServiceConfigurationError err) { |
| 113 | System.err.println("Can't find ScriptEngineFactory providers: " + |
| 114 | err.getMessage()); |
| 115 | if (DEBUG) { |
| 116 | err.printStackTrace(); |
| 117 | } |
| 118 | // do not throw any exception here. user may want to |
| 119 | // manage his/her own factories using this manager |
| 120 | // by explicit registratation (by registerXXX) methods. |
| 121 | return; |
| 122 | } |
| 123 | |
| 124 | try { |
| 125 | while (itr.hasNext()) { |
| 126 | try { |
| 127 | ScriptEngineFactory fact = (ScriptEngineFactory) itr.next(); |
| 128 | engineSpis.add(fact); |
| 129 | } catch (ServiceConfigurationError err) { |
| 130 | System.err.println("ScriptEngineManager providers.next(): " |
| 131 | + err.getMessage()); |
| 132 | if (DEBUG) { |
| 133 | err.printStackTrace(); |
| 134 | } |
| 135 | // one factory failed, but check other factories... |
| 136 | continue; |
| 137 | } |
| 138 | } |
| 139 | } catch (ServiceConfigurationError err) { |
| 140 | System.err.println("ScriptEngineManager providers.hasNext(): " |
| 141 | + err.getMessage()); |
| 142 | if (DEBUG) { |
| 143 | err.printStackTrace(); |
| 144 | } |
| 145 | // do not throw any exception here. user may want to |
| 146 | // manage his/her own factories using this manager |
| 147 | // by explicit registratation (by registerXXX) methods. |
| 148 | return; |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * <code>setBindings</code> stores the specified <code>Bindings</code> |
| 154 | * in the <code>globalScope</code> field. ScriptEngineManager sets this |
| 155 | * <code>Bindings</code> as global bindings for <code>ScriptEngine</code> |
| 156 | * objects created by it. |
| 157 | * |
| 158 | * @param bindings The specified <code>Bindings</code> |
| 159 | * @throws IllegalArgumentException if bindings is null. |
| 160 | */ |
| 161 | public void setBindings(Bindings bindings) { |
| 162 | if (bindings == null) { |
| 163 | throw new IllegalArgumentException("Global scope cannot be null."); |
| 164 | } |
| 165 | |
| 166 | globalScope = bindings; |
| 167 | } |
| 168 | |
| 169 | /** |
| 170 | * <code>getBindings</code> returns the value of the <code>globalScope</code> field. |
| 171 | * ScriptEngineManager sets this <code>Bindings</code> as global bindings for |
| 172 | * <code>ScriptEngine</code> objects created by it. |
| 173 | * |
| 174 | * @return The globalScope field. |
| 175 | */ |
| 176 | public Bindings getBindings() { |
| 177 | return globalScope; |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Sets the specified key/value pair in the Global Scope. |
| 182 | * @param key Key to set |
| 183 | * @param value Value to set. |
| 184 | * @throws NullPointerException if key is null. |
| 185 | * @throws IllegalArgumentException if key is empty string. |
| 186 | */ |
| 187 | public void put(String key, Object value) { |
| 188 | globalScope.put(key, value); |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * Gets the value for the specified key in the Global Scope |
| 193 | * @param key The key whose value is to be returned. |
| 194 | * @return The value for the specified key. |
| 195 | */ |
| 196 | public Object get(String key) { |
| 197 | return globalScope.get(key); |
| 198 | } |
| 199 | |
| 200 | /** |
| 201 | * Looks up and creates a <code>ScriptEngine</code> for a given name. |
| 202 | * The algorithm first searches for a <code>ScriptEngineFactory</code> that has been |
| 203 | * registered as a handler for the specified name using the <code>registerEngineName</code> |
| 204 | * method. |
| 205 | * <br><br> If one is not found, it searches the array of <code>ScriptEngineFactory</code> instances |
| 206 | * stored by the constructor for one with the specified name. If a <code>ScriptEngineFactory</code> |
| 207 | * is found by either method, it is used to create instance of <code>ScriptEngine</code>. |
| 208 | * @param shortName The short name of the <code>ScriptEngine</code> implementation. |
| 209 | * returned by the <code>getNames</code> method of its <code>ScriptEngineFactory</code>. |
| 210 | * @return A <code>ScriptEngine</code> created by the factory located in the search. Returns null |
| 211 | * if no such factory was found. The <code>ScriptEngineManager</code> sets its own <code>globalScope</code> |
| 212 | * <code>Bindings</code> as the <code>GLOBAL_SCOPE</code> <code>Bindings</code> of the newly |
| 213 | * created <code>ScriptEngine</code>. |
| 214 | * @throws NullPointerException if shortName is null. |
| 215 | */ |
| 216 | public ScriptEngine getEngineByName(String shortName) { |
| 217 | if (shortName == null) throw new NullPointerException(); |
| 218 | //look for registered name first |
| 219 | Object obj; |
| 220 | if (null != (obj = nameAssociations.get(shortName))) { |
| 221 | ScriptEngineFactory spi = (ScriptEngineFactory)obj; |
| 222 | try { |
| 223 | ScriptEngine engine = spi.getScriptEngine(); |
| 224 | engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE); |
| 225 | return engine; |
| 226 | } catch (Exception exp) { |
| 227 | if (DEBUG) exp.printStackTrace(); |
| 228 | } |
| 229 | } |
| 230 | |
| 231 | for (ScriptEngineFactory spi : engineSpis) { |
| 232 | List<String> names = null; |
| 233 | try { |
| 234 | names = spi.getNames(); |
| 235 | } catch (Exception exp) { |
| 236 | if (DEBUG) exp.printStackTrace(); |
| 237 | } |
| 238 | |
| 239 | if (names != null) { |
| 240 | for (String name : names) { |
| 241 | if (shortName.equals(name)) { |
| 242 | try { |
| 243 | ScriptEngine engine = spi.getScriptEngine(); |
| 244 | engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE); |
| 245 | return engine; |
| 246 | } catch (Exception exp) { |
| 247 | if (DEBUG) exp.printStackTrace(); |
| 248 | } |
| 249 | } |
| 250 | } |
| 251 | } |
| 252 | } |
| 253 | |
| 254 | return null; |
| 255 | } |
| 256 | |
| 257 | /** |
| 258 | * Look up and create a <code>ScriptEngine</code> for a given extension. The algorithm |
| 259 | * used by <code>getEngineByName</code> is used except that the search starts |
| 260 | * by looking for a <code>ScriptEngineFactory</code> registered to handle the |
| 261 | * given extension using <code>registerEngineExtension</code>. |
| 262 | * @param extension The given extension |
| 263 | * @return The engine to handle scripts with this extension. Returns <code>null</code> |
| 264 | * if not found. |
| 265 | * @throws NullPointerException if extension is null. |
| 266 | */ |
| 267 | public ScriptEngine getEngineByExtension(String extension) { |
| 268 | if (extension == null) throw new NullPointerException(); |
| 269 | //look for registered extension first |
| 270 | Object obj; |
| 271 | if (null != (obj = extensionAssociations.get(extension))) { |
| 272 | ScriptEngineFactory spi = (ScriptEngineFactory)obj; |
| 273 | try { |
| 274 | ScriptEngine engine = spi.getScriptEngine(); |
| 275 | engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE); |
| 276 | return engine; |
| 277 | } catch (Exception exp) { |
| 278 | if (DEBUG) exp.printStackTrace(); |
| 279 | } |
| 280 | } |
| 281 | |
| 282 | for (ScriptEngineFactory spi : engineSpis) { |
| 283 | List<String> exts = null; |
| 284 | try { |
| 285 | exts = spi.getExtensions(); |
| 286 | } catch (Exception exp) { |
| 287 | if (DEBUG) exp.printStackTrace(); |
| 288 | } |
| 289 | if (exts == null) continue; |
| 290 | for (String ext : exts) { |
| 291 | if (extension.equals(ext)) { |
| 292 | try { |
| 293 | ScriptEngine engine = spi.getScriptEngine(); |
| 294 | engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE); |
| 295 | return engine; |
| 296 | } catch (Exception exp) { |
| 297 | if (DEBUG) exp.printStackTrace(); |
| 298 | } |
| 299 | } |
| 300 | } |
| 301 | } |
| 302 | return null; |
| 303 | } |
| 304 | |
| 305 | /** |
| 306 | * Look up and create a <code>ScriptEngine</code> for a given mime type. The algorithm |
| 307 | * used by <code>getEngineByName</code> is used except that the search starts |
| 308 | * by looking for a <code>ScriptEngineFactory</code> registered to handle the |
| 309 | * given mime type using <code>registerEngineMimeType</code>. |
| 310 | * @param mimeType The given mime type |
| 311 | * @return The engine to handle scripts with this mime type. Returns <code>null</code> |
| 312 | * if not found. |
| 313 | * @throws NullPointerException if mimeType is null. |
| 314 | */ |
| 315 | public ScriptEngine getEngineByMimeType(String mimeType) { |
| 316 | if (mimeType == null) throw new NullPointerException(); |
| 317 | //look for registered types first |
| 318 | Object obj; |
| 319 | if (null != (obj = mimeTypeAssociations.get(mimeType))) { |
| 320 | ScriptEngineFactory spi = (ScriptEngineFactory)obj; |
| 321 | try { |
| 322 | ScriptEngine engine = spi.getScriptEngine(); |
| 323 | engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE); |
| 324 | return engine; |
| 325 | } catch (Exception exp) { |
| 326 | if (DEBUG) exp.printStackTrace(); |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | for (ScriptEngineFactory spi : engineSpis) { |
| 331 | List<String> types = null; |
| 332 | try { |
| 333 | types = spi.getMimeTypes(); |
| 334 | } catch (Exception exp) { |
| 335 | if (DEBUG) exp.printStackTrace(); |
| 336 | } |
| 337 | if (types == null) continue; |
| 338 | for (String type : types) { |
| 339 | if (mimeType.equals(type)) { |
| 340 | try { |
| 341 | ScriptEngine engine = spi.getScriptEngine(); |
| 342 | engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE); |
| 343 | return engine; |
| 344 | } catch (Exception exp) { |
| 345 | if (DEBUG) exp.printStackTrace(); |
| 346 | } |
| 347 | } |
| 348 | } |
| 349 | } |
| 350 | return null; |
| 351 | } |
| 352 | |
| 353 | /** |
| 354 | * Returns an array whose elements are instances of all the <code>ScriptEngineFactory</code> classes |
| 355 | * found by the discovery mechanism. |
| 356 | * @return List of all discovered <code>ScriptEngineFactory</code>s. |
| 357 | */ |
| 358 | public List<ScriptEngineFactory> getEngineFactories() { |
| 359 | List<ScriptEngineFactory> res = new ArrayList<ScriptEngineFactory>(engineSpis.size()); |
| 360 | for (ScriptEngineFactory spi : engineSpis) { |
| 361 | res.add(spi); |
| 362 | } |
| 363 | return Collections.unmodifiableList(res); |
| 364 | } |
| 365 | |
| 366 | /** |
| 367 | * Registers a <code>ScriptEngineFactory</code> to handle a language |
| 368 | * name. Overrides any such association found using the Discovery mechanism. |
| 369 | * @param name The name to be associated with the <code>ScriptEngineFactory</code>. |
| 370 | * @param factory The class to associate with the given name. |
| 371 | * @throws NullPointerException if any of the parameters is null. |
| 372 | */ |
| 373 | public void registerEngineName(String name, ScriptEngineFactory factory) { |
| 374 | if (name == null || factory == null) throw new NullPointerException(); |
| 375 | nameAssociations.put(name, factory); |
| 376 | } |
| 377 | |
| 378 | /** |
| 379 | * Registers a <code>ScriptEngineFactory</code> to handle a mime type. |
| 380 | * Overrides any such association found using the Discovery mechanism. |
| 381 | * |
| 382 | * @param type The mime type to be associated with the |
| 383 | * <code>ScriptEngineFactory</code>. |
| 384 | * |
| 385 | * @param factory The class to associate with the given mime type. |
| 386 | * @throws NullPointerException if any of the parameters is null. |
| 387 | */ |
| 388 | public void registerEngineMimeType(String type, ScriptEngineFactory factory) { |
| 389 | if (type == null || factory == null) throw new NullPointerException(); |
| 390 | mimeTypeAssociations.put(type, factory); |
| 391 | } |
| 392 | |
| 393 | /** |
| 394 | * Registers a <code>ScriptEngineFactory</code> to handle an extension. |
| 395 | * Overrides any such association found using the Discovery mechanism. |
| 396 | * |
| 397 | * @param extension The extension type to be associated with the |
| 398 | * <code>ScriptEngineFactory</code>. |
| 399 | * @param factory The class to associate with the given extension. |
| 400 | * @throws NullPointerException if any of the parameters is null. |
| 401 | */ |
| 402 | public void registerEngineExtension(String extension, ScriptEngineFactory factory) { |
| 403 | if (extension == null || factory == null) throw new NullPointerException(); |
| 404 | extensionAssociations.put(extension, factory); |
| 405 | } |
| 406 | |
| 407 | /** Set of script engine factories discovered. */ |
| 408 | private HashSet<ScriptEngineFactory> engineSpis; |
| 409 | |
| 410 | /** Map of engine name to script engine factory. */ |
| 411 | private HashMap<String, ScriptEngineFactory> nameAssociations; |
| 412 | |
| 413 | /** Map of script file extension to script engine factory. */ |
| 414 | private HashMap<String, ScriptEngineFactory> extensionAssociations; |
| 415 | |
| 416 | /** Map of script script MIME type to script engine factory. */ |
| 417 | private HashMap<String, ScriptEngineFactory> mimeTypeAssociations; |
| 418 | |
| 419 | /** Global bindings associated with script engines created by this manager. */ |
| 420 | private Bindings globalScope; |
| 421 | |
| 422 | private boolean canCallerAccessLoader(ClassLoader loader) { |
| 423 | SecurityManager sm = System.getSecurityManager(); |
| 424 | if (sm != null) { |
| 425 | ClassLoader callerLoader = getCallerClassLoader(); |
| 426 | if (callerLoader != null) { |
| 427 | if (loader != callerLoader || !isAncestor(loader, callerLoader)) { |
| 428 | try { |
| 429 | sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); |
| 430 | } catch (SecurityException exp) { |
| 431 | if (DEBUG) exp.printStackTrace(); |
| 432 | return false; |
| 433 | } |
| 434 | } // else fallthru.. |
| 435 | } // else fallthru.. |
| 436 | } // else fallthru.. |
| 437 | |
| 438 | return true; |
| 439 | } |
| 440 | |
| 441 | // Note that this code is same as ClassLoader.getCallerClassLoader(). |
| 442 | // But, that method is package private and hence we can't call here. |
| 443 | private ClassLoader getCallerClassLoader() { |
| 444 | Class caller = Reflection.getCallerClass(3); |
| 445 | if (caller == null) { |
| 446 | return null; |
| 447 | } |
| 448 | return caller.getClassLoader(); |
| 449 | } |
| 450 | |
| 451 | // is cl1 ancestor of cl2? |
| 452 | private boolean isAncestor(ClassLoader cl1, ClassLoader cl2) { |
| 453 | do { |
| 454 | cl2 = cl2.getParent(); |
| 455 | if (cl1 == cl2) return true; |
| 456 | } while (cl2 != null); |
| 457 | return false; |
| 458 | } |
| 459 | } |