Source Code Cross Referenced for LoadService.java in  » Scripting » jruby » org » jruby » runtime » load » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Scripting » jruby » org.jruby.runtime.load 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /***** BEGIN LICENSE BLOCK *****
002:         * Version: CPL 1.0/GPL 2.0/LGPL 2.1
003:         *
004:         * The contents of this file are subject to the Common Public
005:         * License Version 1.0 (the "License"); you may not use this file
006:         * except in compliance with the License. You may obtain a copy of
007:         * the License at http://www.eclipse.org/legal/cpl-v10.html
008:         *
009:         * Software distributed under the License is distributed on an "AS
010:         * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
011:         * implied. See the License for the specific language governing
012:         * rights and limitations under the License.
013:         *
014:         * Copyright (C) 2002-2004 Anders Bengtsson <ndrsbngtssn@yahoo.se>
015:         * Copyright (C) 2002-2004 Jan Arne Petersen <jpetersen@uni-bonn.de>
016:         * Copyright (C) 2004 Thomas E Enebo <enebo@acm.org>
017:         * Copyright (C) 2004-2005 Charles O Nutter <headius@headius.com>
018:         * Copyright (C) 2004 Stefan Matthias Aust <sma@3plus4.de>
019:         * Copyright (C) 2006 Ola Bini <ola@ologix.com>
020:         * 
021:         * Alternatively, the contents of this file may be used under the terms of
022:         * either of the GNU General Public License Version 2 or later (the "GPL"),
023:         * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
024:         * in which case the provisions of the GPL or the LGPL are applicable instead
025:         * of those above. If you wish to allow use of your version of this file only
026:         * under the terms of either the GPL or the LGPL, and not to allow others to
027:         * use your version of this file under the terms of the CPL, indicate your
028:         * decision by deleting the provisions above and replace them with the notice
029:         * and other provisions required by the GPL or the LGPL. If you do not delete
030:         * the provisions above, a recipient may use your version of this file under
031:         * the terms of any one of the CPL, the GPL or the LGPL.
032:         ***** END LICENSE BLOCK *****/package org.jruby.runtime.load;
033:
034:        import java.io.File;
035:        import java.io.FileNotFoundException;
036:        import java.io.IOException;
037:        import java.net.MalformedURLException;
038:        import java.net.URL;
039:        import java.util.Collections;
040:        import java.util.HashMap;
041:        import java.util.HashSet;
042:        import java.util.Iterator;
043:        import java.util.List;
044:        import java.util.Map;
045:        import java.util.Set;
046:        import java.util.jar.JarFile;
047:        import java.util.regex.Matcher;
048:        import java.util.regex.Pattern;
049:
050:        import org.jruby.Ruby;
051:        import org.jruby.RubyArray;
052:        import org.jruby.RubyHash;
053:        import org.jruby.RubyString;
054:        import org.jruby.ast.executable.Script;
055:        import org.jruby.exceptions.RaiseException;
056:        import org.jruby.runtime.Constants;
057:        import org.jruby.runtime.builtin.IRubyObject;
058:        import org.jruby.util.BuiltinScript;
059:        import org.jruby.util.JRubyFile;
060:
061:        /**
062:         * <b>How require works in JRuby</b>
063:         * When requiring a name from Ruby, JRuby will first remove any file extension it knows about,
064:         * thereby making it possible to use this string to see if JRuby has already loaded
065:         * the name in question. If a .rb extension is specified, JRuby will only try
066:         * those extensions when searching. If a .so, .o, .dll, or .jar extension is specified, JRuby
067:         * will only try .so or .jar when searching. Otherwise, JRuby goes through the known suffixes
068:         * (.rb, .rb.ast.ser, .so, and .jar) and tries to find a library with this name. The process for finding a library follows this order
069:         * for all searchable extensions:
070:         * <ol>
071:         * <li>First, check if the name starts with 'jar:', then the path points to a jar-file resource which is returned.</li>
072:         * <li>Second, try searching for the file in the current dir</li>
073:         * <li>Then JRuby looks through the load path trying these variants:
074:         *   <ol>
075:         *     <li>See if the current load path entry starts with 'jar:', if so check if this jar-file contains the name</li>
076:         *     <li>Otherwise JRuby tries to construct a path by combining the entry and the current working directy, and then see if 
077:         *         a file with the correct name can be reached from this point.</li>
078:         *   </ol>
079:         * </li>
080:         * <li>If all these fail, try to load the name as a resource from classloader resources, using the bare name as
081:         *     well as the load path entries</li>
082:         * <li>When we get to this state, the normal JRuby loading has failed. At this stage JRuby tries to load 
083:         *     Java native extensions, by following this process:
084:         *   <ol>
085:         *     <li>First it checks that we haven't already found a library. If we found a library of type JarredScript, the method continues.</li>
086:         *     <li>The first step is translating the name given into a valid Java Extension class name. First it splits the string into 
087:         *     each path segment, and then makes all but the last downcased. After this it takes the last entry, removes all underscores
088:         *     and capitalizes each part separated by underscores. It then joins everything together and tacks on a 'Service' at the end.
089:         *     Lastly, it removes all leading dots, to make it a valid Java FWCN.</li>
090:         *     <li>If the previous library was of type JarredScript, we try to add the jar-file to the classpath</li>
091:         *     <li>Now JRuby tries to instantiate the class with the name constructed. If this works, we return a ClassExtensionLibrary. Otherwise,
092:         *     the old library is put back in place, if there was one.
093:         *   </ol>
094:         * </li>
095:         * <li>When all separate methods have been tried and there was no result, a LoadError will be raised.</li>
096:         * <li>Otherwise, the name will be added to the loaded features, and the library loaded</li>
097:         * </ol>
098:         *
099:         * <b>How to make a class that can get required by JRuby</b>
100:         * <p>First, decide on what name should be used to require the extension.
101:         * In this purely hypothetical example, this name will be 'active_record/connection_adapters/jdbc_adapter'.
102:         * Then create the class name for this require-name, by looking at the guidelines above. Our class should
103:         * be named active_record.connection_adapters.JdbcAdapterService, and implement one of the library-interfaces.
104:         * The easiest one is BasicLibraryService, where you define the basicLoad-method, which will get called
105:         * when your library should be loaded.</p>
106:         * <p>The next step is to either put your compiled class on JRuby's classpath, or package the class/es inside a
107:         * jar-file. To package into a jar-file, we first create the file, then rename it to jdbc_adapter.jar. Then 
108:         * we put this jar-file in the directory active_record/connection_adapters somewhere in JRuby's load path. For
109:         * example, copying jdbc_adapter.jar into JRUBY_HOME/lib/ruby/site_ruby/1.8/active_record/connection_adapters
110:         * will make everything work. If you've packaged your extension inside a RubyGem, write a setub.rb-script that 
111:         * copies the jar-file to this place.</p>
112:         * <p>If you don't want to have the name of your extension-class to be prescribed, you can also put a file called
113:         * jruby-ext.properties in your jar-files META-INF directory, where you can use the key <full-extension-name>.impl
114:         * to make the extension library load the correct class. An example for the above would have a jruby-ext.properties
115:         * that contained a ruby like: "active_record/connection_adapters/jdbc_adapter=org.jruby.ar.JdbcAdapter". (NOTE: THIS
116:         * FEATURE IS NOT IMPLEMENTED YET.)</p>
117:         *
118:         * @author jpetersen
119:         */
120:        public class LoadService {
121:            protected static final String JRUBY_BUILTIN_SUFFIX = ".rb";
122:
123:            protected static final String[] sourceSuffixes = { ".rb" };
124:            protected static final String[] extensionSuffixes = { ".so", ".jar" };
125:            protected static final String[] allSuffixes = { ".rb", ".so",
126:                    ".jar" };
127:            protected static final Pattern sourcePattern = Pattern
128:                    .compile("\\.(?:rb)$");
129:            protected static final Pattern extensionPattern = Pattern
130:                    .compile("\\.(?:so|o|dll|jar)$");
131:
132:            protected final RubyArray loadPath;
133:            protected final RubyArray loadedFeatures;
134:            protected final Set loadedFeaturesInternal = Collections
135:                    .synchronizedSet(new HashSet());
136:            protected final Set firstLineLoadedFeatures = Collections
137:                    .synchronizedSet(new HashSet());
138:            protected final Map builtinLibraries = new HashMap();
139:
140:            protected final Map jarFiles = new HashMap();
141:
142:            protected final Map autoloadMap = new HashMap();
143:
144:            protected final Ruby runtime;
145:
146:            public LoadService(Ruby runtime) {
147:                this .runtime = runtime;
148:                loadPath = RubyArray.newArray(runtime);
149:                loadedFeatures = RubyArray.newArray(runtime);
150:            }
151:
152:            public void init(List additionalDirectories) {
153:                // add all startup load paths to the list first
154:                for (Iterator iter = additionalDirectories.iterator(); iter
155:                        .hasNext();) {
156:                    addPath((String) iter.next());
157:                }
158:
159:                // add $RUBYLIB paths
160:                RubyHash env = (RubyHash) runtime.getObject()
161:                        .getConstant("ENV");
162:                RubyString env_rubylib = runtime.newString("RUBYLIB");
163:                if (env.has_key(env_rubylib).isTrue()) {
164:                    String rubylib = env.aref(env_rubylib).toString();
165:                    String[] paths = rubylib.split(File.pathSeparator);
166:                    for (int i = 0; i < paths.length; i++) {
167:                        addPath(paths[i]);
168:                    }
169:                }
170:
171:                // wrap in try/catch for security exceptions in an applet
172:                if (!Ruby.isSecurityRestricted()) {
173:                    String jrubyHome = runtime.getJRubyHome();
174:                    if (jrubyHome != null) {
175:                        char sep = '/';
176:                        String rubyDir = jrubyHome + sep + "lib" + sep + "ruby"
177:                                + sep;
178:
179:                        addPath(rubyDir + "site_ruby" + sep
180:                                + Constants.RUBY_MAJOR_VERSION);
181:                        addPath(rubyDir + "site_ruby");
182:                        addPath(rubyDir + Constants.RUBY_MAJOR_VERSION);
183:                        addPath(rubyDir + Constants.RUBY_MAJOR_VERSION + sep
184:                                + "java");
185:
186:                        // Added to make sure we find default distribution files within jar file.
187:                        // TODO: Either make jrubyHome become the jar file or allow "classpath-only" paths
188:                        addPath("lib" + sep + "ruby" + sep
189:                                + Constants.RUBY_MAJOR_VERSION);
190:                    }
191:                }
192:
193:                // "." dir is used for relative path loads from a given file, as in require '../foo/bar'
194:                if (runtime.getSafeLevel() == 0) {
195:                    addPath(".");
196:                }
197:            }
198:
199:            private void addPath(String path) {
200:                // Empty paths do not need to be added
201:                if (path == null || path.length() == 0)
202:                    return;
203:
204:                synchronized (loadPath) {
205:                    loadPath.add(runtime.newString(path.replace('\\', '/')));
206:                }
207:            }
208:
209:            public void load(String file) {
210:                if (!runtime.getProfile().allowLoad(file)) {
211:                    throw runtime.newLoadError("No such file to load -- "
212:                            + file);
213:                }
214:
215:                Library library = null;
216:
217:                library = findLibrary(file);
218:
219:                if (library == null) {
220:                    library = findLibraryWithClassloaders(file);
221:                    if (library == null) {
222:                        throw runtime.newLoadError("No such file to load -- "
223:                                + file);
224:                    }
225:                }
226:                try {
227:                    library.load(runtime);
228:                } catch (IOException e) {
229:                    throw runtime.newLoadError("IO error -- " + file);
230:                }
231:            }
232:
233:            public boolean smartLoad(String file) {
234:                if (firstLineLoadedFeatures.contains(file)) {
235:                    return false;
236:                }
237:                Library library = null;
238:                String loadName = file;
239:                String[] extensionsToSearch = null;
240:
241:                // if an extension is specified, try more targetted searches
242:                if (file.lastIndexOf('.') > file.lastIndexOf('/')) {
243:                    Matcher matcher = null;
244:                    if ((matcher = sourcePattern.matcher(file)).find()) {
245:                        // source extensions
246:                        extensionsToSearch = sourceSuffixes;
247:
248:                        // trim extension to try other options
249:                        file = file.substring(0, matcher.start());
250:                    } else if ((matcher = extensionPattern.matcher(file))
251:                            .find()) {
252:                        // extension extensions
253:                        extensionsToSearch = extensionSuffixes;
254:
255:                        // trim extension to try other options
256:                        file = file.substring(0, matcher.start());
257:                    } else {
258:                        // unknown extension, fall back to search with extensions
259:                        extensionsToSearch = allSuffixes;
260:                    }
261:                } else {
262:                    // try all extensions
263:                    extensionsToSearch = allSuffixes;
264:                }
265:
266:                // First try suffixes with normal loading
267:                for (int i = 0; i < extensionsToSearch.length; i++) {
268:                    library = findLibrary(file + extensionsToSearch[i]);
269:                    if (library != null) {
270:                        loadName = file + extensionsToSearch[i];
271:                        break;
272:                    }
273:                }
274:
275:                // Then try suffixes with classloader loading
276:                if (library == null) {
277:                    for (int i = 0; i < extensionsToSearch.length; i++) {
278:                        library = findLibraryWithClassloaders(file
279:                                + extensionsToSearch[i]);
280:                        if (library != null) {
281:                            loadName = file + extensionsToSearch[i];
282:                            break;
283:                        }
284:                    }
285:                }
286:
287:                library = tryLoadExtension(library, file);
288:
289:                // no library or extension found, try to load directly as a class
290:                Script script = null;
291:                if (library == null) {
292:                    String className = file;
293:                    if (file.lastIndexOf(".") > file.lastIndexOf("/")) {
294:                        className = file.substring(file.lastIndexOf(".") + 1);
295:                    }
296:                    className = className.replace('/', '.');
297:                    try {
298:                        Class scriptClass = Class.forName(className);
299:                        script = (Script) scriptClass.newInstance();
300:                    } catch (Exception cnfe) {
301:                        throw runtime.newLoadError("no such file to load -- "
302:                                + file);
303:                    }
304:                }
305:
306:                if (loadedFeaturesInternal.contains(loadName)
307:                        || loadedFeatures
308:                                .include_p(runtime.newString(loadName))
309:                                .isTrue()) {
310:                    return false;
311:                }
312:
313:                // attempt to load the found library
314:                try {
315:                    loadedFeaturesInternal.add(loadName);
316:                    firstLineLoadedFeatures.add(file);
317:                    synchronized (loadedFeatures) {
318:                        loadedFeatures.append(runtime.newString(loadName));
319:                    }
320:
321:                    if (script != null) {
322:                        runtime.loadScript(script);
323:                        return true;
324:                    }
325:
326:                    library.load(runtime);
327:                    return true;
328:                } catch (Exception e) {
329:                    if (library instanceof  JarredScript
330:                            && file.endsWith(".jar")) {
331:                        return true;
332:                    }
333:
334:                    loadedFeaturesInternal.remove(loadName);
335:                    firstLineLoadedFeatures.remove(file);
336:                    synchronized (loadedFeatures) {
337:                        loadedFeatures.remove(runtime.newString(loadName));
338:                    }
339:                    if (e instanceof  RaiseException)
340:                        throw (RaiseException) e;
341:
342:                    if (runtime.getDebug().isTrue())
343:                        e.printStackTrace();
344:
345:                    RaiseException re = runtime.newLoadError("IO error -- "
346:                            + file);
347:                    re.initCause(e);
348:                    throw re;
349:                }
350:            }
351:
352:            public boolean require(String file) {
353:                if (!runtime.getProfile().allowRequire(file)) {
354:                    throw runtime.newLoadError("No such file to load -- "
355:                            + file);
356:                }
357:                return smartLoad(file);
358:            }
359:
360:            public IRubyObject getLoadPath() {
361:                return loadPath;
362:            }
363:
364:            public IRubyObject getLoadedFeatures() {
365:                return loadedFeatures;
366:            }
367:
368:            public IAutoloadMethod autoloadFor(String name) {
369:                return (IAutoloadMethod) autoloadMap.get(name);
370:            }
371:
372:            public void removeAutoLoadFor(String name) {
373:                autoloadMap.remove(name);
374:            }
375:
376:            public IRubyObject autoload(String name) {
377:                IAutoloadMethod loadMethod = (IAutoloadMethod) autoloadMap
378:                        .remove(name);
379:                if (loadMethod != null) {
380:                    return loadMethod.load(runtime, name);
381:                }
382:                return null;
383:            }
384:
385:            public void addAutoload(String name, IAutoloadMethod loadMethod) {
386:                autoloadMap.put(name, loadMethod);
387:            }
388:
389:            public void registerBuiltin(String name, Library library) {
390:                builtinLibraries.put(name, library);
391:            }
392:
393:            public void registerRubyBuiltin(String libraryName) {
394:                registerBuiltin(libraryName + JRUBY_BUILTIN_SUFFIX,
395:                        new BuiltinScript(libraryName));
396:            }
397:
398:            private Library findLibrary(String file) {
399:                if (builtinLibraries.containsKey(file)) {
400:                    return (Library) builtinLibraries.get(file);
401:                }
402:
403:                LoadServiceResource resource = findFile(file);
404:                if (resource == null) {
405:                    return null;
406:                }
407:
408:                if (file.endsWith(".jar")) {
409:                    return new JarredScript(resource);
410:                } else {
411:                    return new ExternalScript(resource, file);
412:                }
413:            }
414:
415:            private Library findLibraryWithClassloaders(String file) {
416:                LoadServiceResource resource = findFileInClasspath(file);
417:                if (resource == null) {
418:                    return null;
419:                }
420:
421:                if (file.endsWith(".jar")) {
422:                    return new JarredScript(resource);
423:                } else {
424:                    return new ExternalScript(resource, file);
425:                }
426:            }
427:
428:            /**
429:             * this method uses the appropriate lookup strategy to find a file.
430:             * It is used by Kernel#require.
431:             *
432:             * @mri rb_find_file
433:             * @param name the file to find, this is a path name
434:             * @return the correct file
435:             */
436:            private LoadServiceResource findFile(String name) {
437:                // if a jar URL, return load service resource directly without further searching
438:                if (name.startsWith("jar:")) {
439:                    try {
440:                        return new LoadServiceResource(new URL(name), name);
441:                    } catch (MalformedURLException e) {
442:                        throw runtime.newIOErrorFromException(e);
443:                    }
444:                }
445:
446:                // check current directory; if file exists, retrieve URL and return resource
447:                try {
448:                    JRubyFile file = JRubyFile.create(runtime
449:                            .getCurrentDirectory(), name);
450:                    if (file.isFile() && file.isAbsolute()) {
451:                        try {
452:                            return new LoadServiceResource(
453:                                    file.toURI().toURL(), name);
454:                        } catch (MalformedURLException e) {
455:                            throw runtime.newIOErrorFromException(e);
456:                        }
457:                    }
458:                } catch (IllegalArgumentException illArgEx) {
459:                } catch (SecurityException secEx) {
460:                }
461:
462:                for (Iterator pathIter = loadPath.getList().iterator(); pathIter
463:                        .hasNext();) {
464:                    String entry = pathIter.next().toString();
465:                    if (entry.startsWith("jar:")) {
466:                        JarFile current = (JarFile) jarFiles.get(entry);
467:                        if (null == current) {
468:                            try {
469:                                current = new JarFile(entry.substring(4));
470:                                jarFiles.put(entry, current);
471:                            } catch (FileNotFoundException ignored) {
472:                            } catch (IOException e) {
473:                                throw runtime.newIOErrorFromException(e);
474:                            }
475:                        }
476:
477:                        if (current.getJarEntry(name) != null) {
478:                            try {
479:                                return new LoadServiceResource(new URL(
480:                                        "jar:file:" + entry.substring(4) + "!/"
481:                                                + name), entry + name);
482:                            } catch (MalformedURLException e) {
483:                                throw runtime.newIOErrorFromException(e);
484:                            }
485:                        }
486:                    }
487:
488:                    try {
489:                        JRubyFile current = JRubyFile.create(JRubyFile.create(
490:                                runtime.getCurrentDirectory(), entry)
491:                                .getAbsolutePath(), name);
492:                        if (current.isFile()) {
493:                            try {
494:                                return new LoadServiceResource(current.toURI()
495:                                        .toURL(), current.getPath());
496:                            } catch (MalformedURLException e) {
497:                                throw runtime.newIOErrorFromException(e);
498:                            }
499:                        }
500:                    } catch (SecurityException secEx) {
501:                    }
502:                }
503:
504:                return null;
505:            }
506:
507:            /**
508:             * this method uses the appropriate lookup strategy to find a file.
509:             * It is used by Kernel#require.
510:             *
511:             * @mri rb_find_file
512:             * @param name the file to find, this is a path name
513:             * @return the correct file
514:             */
515:            private LoadServiceResource findFileInClasspath(String name) {
516:                // Look in classpath next (we do not use File as a test since UNC names will match)
517:                // Note: Jar resources must NEVER begin with an '/'. (previous code said "always begin with a /")
518:                ClassLoader classLoader = Thread.currentThread()
519:                        .getContextClassLoader();
520:
521:                for (Iterator pathIter = loadPath.getList().iterator(); pathIter
522:                        .hasNext();) {
523:                    String entry = pathIter.next().toString();
524:
525:                    // if entry starts with a slash, skip it since classloader resources never start with a /
526:                    if (entry.charAt(0) == '/'
527:                            || (entry.length() > 1 && entry.charAt(1) == ':'))
528:                        continue;
529:
530:                    // otherwise, try to load from classpath (Note: Jar resources always uses '/')
531:                    URL loc = classLoader.getResource(entry + "/" + name);
532:
533:                    // Make sure this is not a directory or unavailable in some way
534:                    if (isRequireable(loc)) {
535:                        return new LoadServiceResource(loc, loc.getPath());
536:                    }
537:                }
538:
539:                // if name starts with a / we're done (classloader resources won't load with an initial /)
540:                if (name.charAt(0) == '/'
541:                        || (name.length() > 1 && name.charAt(1) == ':'))
542:                    return null;
543:
544:                // Try to load from classpath without prefix. "A/b.rb" will not load as 
545:                // "./A/b.rb" in a jar file.
546:                URL loc = classLoader.getResource(name);
547:
548:                return isRequireable(loc) ? new LoadServiceResource(loc, loc
549:                        .getPath()) : null;
550:            }
551:
552:            private Library tryLoadExtension(Library library, String file) {
553:                // This code exploits the fact that all .jar files will be found for the JarredScript feature.
554:                // This is where the basic extension mechanism gets fixed
555:                Library oldLibrary = library;
556:
557:                if ((library == null || library instanceof  JarredScript)
558:                        && !file.equalsIgnoreCase("")) {
559:                    // Create package name, by splitting on / and joining all but the last elements with a ".", and downcasing them.
560:                    String[] all = file.split("/");
561:                    StringBuffer finName = new StringBuffer();
562:                    for (int i = 0, j = (all.length - 1); i < j; i++) {
563:                        finName.append(all[i].toLowerCase()).append(".");
564:
565:                    }
566:
567:                    // Make the class name look nice, by splitting on _ and capitalize each segment, then joining
568:                    // the, together without anything separating them, and last put on "Service" at the end.
569:                    String[] last = all[all.length - 1].split("_");
570:                    for (int i = 0, j = last.length; i < j; i++) {
571:                        finName
572:                                .append(
573:                                        Character
574:                                                .toUpperCase(last[i].charAt(0)))
575:                                .append(last[i].substring(1));
576:                    }
577:                    finName.append("Service");
578:
579:                    // We don't want a package name beginning with dots, so we remove them
580:                    String className = finName.toString().replaceAll("^\\.*",
581:                            "");
582:
583:                    // If there is a jar-file with the required name, we add this to the class path.
584:                    if (library instanceof  JarredScript) {
585:                        // It's _really_ expensive to check that the class actually exists in the Jar, so
586:                        // we don't do that now.
587:                        runtime.getJavaSupport()
588:                                .addToClasspath(
589:                                        ((JarredScript) library).getResource()
590:                                                .getURL());
591:                    }
592:
593:                    try {
594:                        Class theClass = runtime.getJavaSupport()
595:                                .loadJavaClass(className);
596:                        library = new ClassExtensionLibrary(theClass);
597:                    } catch (Exception ee) {
598:                        library = null;
599:                        runtime.getGlobalVariables()
600:                                .set("$!", runtime.getNil());
601:                    }
602:                }
603:
604:                // If there was a good library before, we go back to that
605:                if (library == null && oldLibrary != null) {
606:                    library = oldLibrary;
607:                }
608:                return library;
609:            }
610:
611:            /* Directories and unavailable resources are not able to open a stream. */
612:            private boolean isRequireable(URL loc) {
613:                if (loc != null) {
614:                    if (loc.getProtocol().equals("file")
615:                            && new java.io.File(loc.getFile()).isDirectory()) {
616:                        return false;
617:                    }
618:
619:                    try {
620:                        loc.openConnection();
621:                        return true;
622:                    } catch (Exception e) {
623:                    }
624:                }
625:                return false;
626:            }
627:        }
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