001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.camel.util; 018 019 import java.io.File; 020 import java.io.FileInputStream; 021 import java.io.IOException; 022 import java.io.InputStream; 023 import java.lang.annotation.Annotation; 024 import java.lang.reflect.Method; 025 import java.net.URL; 026 import java.net.URLConnection; 027 import java.net.URLDecoder; 028 import java.util.Arrays; 029 import java.util.Enumeration; 030 import java.util.HashSet; 031 import java.util.Set; 032 import java.util.jar.JarEntry; 033 import java.util.jar.JarInputStream; 034 035 import org.apache.commons.logging.Log; 036 import org.apache.commons.logging.LogFactory; 037 038 /** 039 * <p> 040 * ResolverUtil is used to locate classes that are available in the/a class path 041 * and meet arbitrary conditions. The two most common conditions are that a 042 * class implements/extends another class, or that is it annotated with a 043 * specific annotation. However, through the use of the {@link Test} class it is 044 * possible to search using arbitrary conditions. 045 * </p> 046 * <p/> 047 * <p> 048 * A ClassLoader is used to locate all locations (directories and jar files) in 049 * the class path that contain classes within certain packages, and then to load 050 * those classes and check them. By default the ClassLoader returned by 051 * {@code Thread.currentThread().getContextClassLoader()} is used, but this can 052 * be overridden by calling {@link #setClassLoaders(Set)} prior to 053 * invoking any of the {@code find()} methods. 054 * </p> 055 * <p/> 056 * <p> 057 * General searches are initiated by calling the 058 * {@link #find(ResolverUtil.Test, String)} ()} method and supplying a package 059 * name and a Test instance. This will cause the named package <b>and all 060 * sub-packages</b> to be scanned for classes that meet the test. There are 061 * also utility methods for the common use cases of scanning multiple packages 062 * for extensions of particular classes, or classes annotated with a specific 063 * annotation. 064 * </p> 065 * <p/> 066 * <p> 067 * The standard usage pattern for the ResolverUtil class is as follows: 068 * </p> 069 * <p/> 070 * <pre> 071 * resolverUtil<ActionBean> resolver = new ResolverUtil<ActionBean>(); 072 * resolver.findImplementation(ActionBean.class, pkg1, pkg2); 073 * resolver.find(new CustomTest(), pkg1); 074 * resolver.find(new CustomTest(), pkg2); 075 * collection<ActionBean> beans = resolver.getClasses(); 076 * </pre> 077 * 078 * @author Tim Fennell 079 */ 080 public class ResolverUtil<T> { 081 protected static final transient Log LOG = LogFactory.getLog(ResolverUtil.class); 082 083 /** 084 * A simple interface that specifies how to test classes to determine if 085 * they are to be included in the results produced by the ResolverUtil. 086 */ 087 public static interface Test { 088 /** 089 * Will be called repeatedly with candidate classes. Must return True if 090 * a class is to be included in the results, false otherwise. 091 */ 092 boolean matches(Class type); 093 } 094 095 /** 096 * A Test that checks to see if each class is assignable to the provided 097 * class. Note that this test will match the parent type itself if it is 098 * presented for matching. 099 */ 100 public static class IsA implements Test { 101 private Class parent; 102 103 /** 104 * Constructs an IsA test using the supplied Class as the parent 105 * class/interface. 106 */ 107 public IsA(Class parentType) { 108 this.parent = parentType; 109 } 110 111 /** 112 * Returns true if type is assignable to the parent type supplied in the 113 * constructor. 114 */ 115 public boolean matches(Class type) { 116 return type != null && parent.isAssignableFrom(type); 117 } 118 119 @Override 120 public String toString() { 121 return "is assignable to " + parent.getSimpleName(); 122 } 123 } 124 125 /** 126 * A Test that checks to see if each class is annotated with a specific 127 * annotation. If it is, then the test returns true, otherwise false. 128 */ 129 public static class AnnotatedWith implements Test { 130 private Class<? extends Annotation> annotation; 131 private boolean checkMetaAnnotations; 132 133 /** 134 * Constructs an AnnotatedWith test for the specified annotation type. 135 */ 136 public AnnotatedWith(Class<? extends Annotation> annotation) { 137 this(annotation, false); 138 } 139 140 /** 141 * Constructs an AnnotatedWith test for the specified annotation type. 142 */ 143 public AnnotatedWith(Class<? extends Annotation> annotation, boolean checkMetaAnnotations) { 144 this.annotation = annotation; 145 this.checkMetaAnnotations = checkMetaAnnotations; 146 } 147 148 /** 149 * Returns true if the type is annotated with the class provided to the 150 * constructor. 151 */ 152 public boolean matches(Class type) { 153 return type != null && ObjectHelper.hasAnnotation(type, annotation, checkMetaAnnotations); 154 } 155 156 @Override 157 public String toString() { 158 return "annotated with @" + annotation.getSimpleName(); 159 } 160 } 161 162 /** 163 * The set of matches being accumulated. 164 */ 165 private Set<Class<? extends T>> matches = new HashSet<Class<? extends T>>(); 166 167 /** 168 * The ClassLoader to use when looking for classes. If null then the 169 * ClassLoader returned by Thread.currentThread().getContextClassLoader() 170 * will be used. 171 */ 172 private Set<ClassLoader> classLoaders; 173 174 /** 175 * Provides access to the classes discovered so far. If no calls have been 176 * made to any of the {@code find()} methods, this set will be empty. 177 * 178 * @return the set of classes that have been discovered. 179 */ 180 public Set<Class<? extends T>> getClasses() { 181 return matches; 182 } 183 184 185 /** 186 * Returns the classloaders that will be used for scanning for classes. If no 187 * explicit ClassLoader has been set by the calling, the context class 188 * loader will and the one that has loaded this class ResolverUtil be used. 189 * 190 * @return the ClassLoader instances that will be used to scan for classes 191 */ 192 public Set<ClassLoader> getClassLoaders() { 193 if (classLoaders == null) { 194 classLoaders = new HashSet<ClassLoader>(); 195 classLoaders.add(Thread.currentThread().getContextClassLoader()); 196 classLoaders.add(ResolverUtil.class.getClassLoader()); 197 } 198 return classLoaders; 199 } 200 201 /** 202 * Sets the ClassLoader instances that should be used when scanning for 203 * classes. If none is set then the context classloader will be used. 204 * 205 * @param classLoaders a ClassLoader to use when scanning for classes 206 */ 207 public void setClassLoaders(Set<ClassLoader> classLoaders) { 208 this.classLoaders = classLoaders; 209 } 210 211 /** 212 * Attempts to discover classes that are assignable to the type provided. In 213 * the case that an interface is provided this method will collect 214 * implementations. In the case of a non-interface class, subclasses will be 215 * collected. Accumulated classes can be accessed by calling 216 * {@link #getClasses()}. 217 * 218 * @param parent the class of interface to find subclasses or 219 * implementations of 220 * @param packageNames one or more package names to scan (including 221 * subpackages) for classes 222 */ 223 public void findImplementations(Class parent, String... packageNames) { 224 if (packageNames == null) { 225 return; 226 } 227 228 if (LOG.isDebugEnabled()) { 229 LOG.debug("Searching for implementations of " + parent.getName() + " in packages: " + Arrays 230 .asList(packageNames)); 231 } 232 233 Test test = new IsA(parent); 234 for (String pkg : packageNames) { 235 find(test, pkg); 236 } 237 238 if (LOG.isDebugEnabled()) { 239 LOG.debug("Found: " + getClasses()); 240 } 241 } 242 243 /** 244 * Attempts to discover classes that are annotated with to the annotation. 245 * Accumulated classes can be accessed by calling {@link #getClasses()}. 246 * 247 * @param annotation the annotation that should be present on matching 248 * classes 249 * @param packageNames one or more package names to scan (including 250 * subpackages) for classes 251 */ 252 public void findAnnotated(Class<? extends Annotation> annotation, String... packageNames) { 253 if (packageNames == null) { 254 return; 255 } 256 257 if (LOG.isDebugEnabled()) { 258 LOG.debug("Searching for annotations of " + annotation.getName() + " in packages: " + Arrays 259 .asList(packageNames)); 260 } 261 262 Test test = new AnnotatedWith(annotation, true); 263 for (String pkg : packageNames) { 264 find(test, pkg); 265 } 266 267 if (LOG.isDebugEnabled()) { 268 LOG.debug("Found: " + getClasses()); 269 } 270 } 271 272 /** 273 * Scans for classes starting at the package provided and descending into 274 * subpackages. Each class is offered up to the Test as it is discovered, 275 * and if the Test returns true the class is retained. Accumulated classes 276 * can be fetched by calling {@link #getClasses()}. 277 * 278 * @param test an instance of {@link Test} that will be used to filter 279 * classes 280 * @param packageName the name of the package from which to start scanning 281 * for classes, e.g. {@code net.sourceforge.stripes} 282 */ 283 public void find(Test test, String packageName) { 284 packageName = packageName.replace('.', '/'); 285 286 Set<ClassLoader> set = getClassLoaders(); 287 288 ClassLoader osgiClassLoader = getOsgiClassLoader(set); 289 290 if (osgiClassLoader != null) { 291 // if we have an osgi bundle loader use this one only 292 LOG.debug("Using only osgi bundle classloader"); 293 find(test, packageName, osgiClassLoader, true); 294 } else { 295 LOG.debug("Using only regular classloaders"); 296 for (ClassLoader classLoader : set) { 297 if (!isOsgiClassloader(classLoader)) { 298 find(test, packageName, classLoader, false); 299 } 300 } 301 } 302 } 303 304 /** 305 * Gets the osgi classloader if any in the given set 306 */ 307 private static ClassLoader getOsgiClassLoader(Set<ClassLoader> set) { 308 for (ClassLoader loader : set) { 309 if (isOsgiClassloader(loader)) { 310 return loader; 311 } 312 } 313 return null; 314 } 315 316 /** 317 * Is it an osgi classloader 318 */ 319 private static boolean isOsgiClassloader(ClassLoader loader) { 320 try { 321 Method mth = loader.getClass().getMethod("getBundle", new Class[]{}); 322 if (mth != null) { 323 return true; 324 } 325 } catch (NoSuchMethodException e) { 326 // ignore its not an osgi loader 327 } 328 return false; 329 } 330 331 /** 332 * Tries to find the reosurce in the package using the class loader. 333 * <p/> 334 * Will handle both plain URL based classloaders and OSGi bundle loaders. 335 * 336 * @param test what to find 337 * @param packageName the package to search in 338 * @param loader the class loader 339 * @param osgi true if its a osgi bundle loader, false if regular classloader 340 */ 341 protected void find(Test test, String packageName, ClassLoader loader, boolean osgi) { 342 if (LOG.isTraceEnabled()) { 343 LOG.trace("Searching for: " + test + " in package: " + packageName + " using classloader: " 344 + loader.getClass().getName() + " osgi bundle classloader: " + osgi); 345 } 346 347 if (osgi) { 348 try { 349 Method mth = loader.getClass().getMethod("getBundle", new Class[]{}); 350 if (mth != null) { 351 if (LOG.isDebugEnabled()) { 352 LOG.debug("Loading from osgi buindle using classloader: " + loader); 353 } 354 loadImplementationsInBundle(test, packageName, loader, mth); 355 return; 356 } 357 } catch (NoSuchMethodException e) { 358 LOG.warn("It's not an osgi bundle classloader: " + loader); 359 return; 360 } 361 } 362 363 Enumeration<URL> urls; 364 try { 365 urls = getResources(loader, packageName); 366 if (!urls.hasMoreElements()) { 367 LOG.trace("No URLs returned by classloader"); 368 } 369 } catch (IOException ioe) { 370 LOG.warn("Could not read package: " + packageName, ioe); 371 return; 372 } 373 374 while (urls.hasMoreElements()) { 375 URL url = null; 376 try { 377 url = urls.nextElement(); 378 if (LOG.isTraceEnabled()) { 379 LOG.trace("URL from classloader: " + url); 380 } 381 382 String urlPath = url.getFile(); 383 urlPath = URLDecoder.decode(urlPath, "UTF-8"); 384 if (LOG.isTraceEnabled()) { 385 LOG.trace("Decoded urlPath: " + urlPath); 386 } 387 388 // If it's a file in a directory, trim the stupid file: spec 389 if (urlPath.startsWith("file:")) { 390 urlPath = urlPath.substring(5); 391 } 392 393 // osgi bundles should be skipped 394 if (url.toString().startsWith("bundle:") || urlPath.startsWith("bundle:")) { 395 LOG.trace("It's a virtual osgi bundle, skipping"); 396 continue; 397 } 398 399 // Else it's in a JAR, grab the path to the jar 400 if (urlPath.indexOf('!') > 0) { 401 urlPath = urlPath.substring(0, urlPath.indexOf('!')); 402 } 403 404 if (LOG.isTraceEnabled()) { 405 LOG.trace("Scanning for classes in [" + urlPath + "] matching criteria: " + test); 406 } 407 408 File file = new File(urlPath); 409 if (file.isDirectory()) { 410 if (LOG.isDebugEnabled()) { 411 LOG.debug("Loading from directory: " + file); 412 } 413 loadImplementationsInDirectory(test, packageName, file); 414 } else { 415 InputStream stream; 416 if (urlPath.startsWith("http:")) { 417 // load resources using http such as java webstart 418 LOG.debug("The current jar is accessed via http"); 419 URL urlStream = new URL(urlPath); 420 URLConnection con = urlStream.openConnection(); 421 // disable cache mainly to avoid jar file locking on Windows 422 con.setUseCaches(false); 423 stream = con.getInputStream(); 424 } else { 425 stream = new FileInputStream(file); 426 } 427 428 if (LOG.isDebugEnabled()) { 429 LOG.debug("Loading from jar: " + file); 430 } 431 loadImplementationsInJar(test, packageName, stream, urlPath); 432 } 433 } catch (IOException ioe) { 434 LOG.warn("Could not read entries in url: " + url, ioe); 435 } 436 } 437 } 438 439 /** 440 * Strategy to get the resources by the given classloader. 441 * <p/> 442 * Notice that in WebSphere platforms there is a {@link org.apache.camel.util.WebSphereResolverUtil} 443 * to take care of WebSphere's odditiy of resource loading. 444 * 445 * @param loader the classloader 446 * @param packageName the packagename for the package to load 447 * @return URL's for the given package 448 * @throws IOException is thrown by the classloader 449 */ 450 protected Enumeration<URL> getResources(ClassLoader loader, String packageName) throws IOException { 451 if (LOG.isTraceEnabled()) { 452 LOG.trace("Getting resource URL for package: " + packageName + " with classloader: " + loader); 453 } 454 return loader.getResources(packageName); 455 } 456 457 private void loadImplementationsInBundle(Test test, String packageName, ClassLoader loader, Method mth) { 458 // Use an inner class to avoid a NoClassDefFoundError when used in a non-osgi env 459 Set<String> urls = OsgiUtil.getImplementationsInBundle(test, packageName, loader, mth); 460 if (urls != null) { 461 for (String url : urls) { 462 // substring to avoid leading slashes 463 addIfMatching(test, url); 464 } 465 } 466 } 467 468 private static final class OsgiUtil { 469 private OsgiUtil() { 470 // Helper class 471 } 472 static Set<String> getImplementationsInBundle(Test test, String packageName, ClassLoader loader, Method mth) { 473 try { 474 org.osgi.framework.Bundle bundle = (org.osgi.framework.Bundle) mth.invoke(loader); 475 org.osgi.framework.Bundle[] bundles = bundle.getBundleContext().getBundles(); 476 Set<String> urls = new HashSet<String>(); 477 for (org.osgi.framework.Bundle bd : bundles) { 478 if (LOG.isTraceEnabled()) { 479 LOG.trace("Searching in bundle:" + bd); 480 } 481 Enumeration<URL> paths = bd.findEntries("/" + packageName, "*.class", true); 482 while (paths != null && paths.hasMoreElements()) { 483 URL path = paths.nextElement(); 484 urls.add(path.getPath().substring(1)); 485 } 486 } 487 return urls; 488 } catch (Throwable t) { 489 LOG.error("Could not search osgi bundles for classes matching criteria: " + test 490 + "due to an Exception: " + t.getMessage()); 491 return null; 492 } 493 } 494 } 495 496 497 /** 498 * Finds matches in a physical directory on a filesystem. Examines all files 499 * within a directory - if the File object is not a directory, and ends with 500 * <i>.class</i> the file is loaded and tested to see if it is acceptable 501 * according to the Test. Operates recursively to find classes within a 502 * folder structure matching the package structure. 503 * 504 * @param test a Test used to filter the classes that are discovered 505 * @param parent the package name up to this directory in the package 506 * hierarchy. E.g. if /classes is in the classpath and we wish to 507 * examine files in /classes/org/apache then the values of 508 * <i>parent</i> would be <i>org/apache</i> 509 * @param location a File object representing a directory 510 */ 511 private void loadImplementationsInDirectory(Test test, String parent, File location) { 512 File[] files = location.listFiles(); 513 StringBuilder builder = null; 514 515 for (File file : files) { 516 builder = new StringBuilder(100); 517 String name = file.getName(); 518 if (name != null) { 519 name = name.trim(); 520 builder.append(parent).append("/").append(name); 521 String packageOrClass = parent == null ? name : builder.toString(); 522 523 if (file.isDirectory()) { 524 loadImplementationsInDirectory(test, packageOrClass, file); 525 } else if (name.endsWith(".class")) { 526 addIfMatching(test, packageOrClass); 527 } 528 } 529 } 530 } 531 532 /** 533 * Finds matching classes within a jar files that contains a folder 534 * structure matching the package structure. If the File is not a JarFile or 535 * does not exist a warning will be logged, but no error will be raised. 536 * 537 * @param test a Test used to filter the classes that are discovered 538 * @param parent the parent package under which classes must be in order to 539 * be considered 540 * @param jarfile the jar file to be examined for classes 541 * @param stream the inputstream of the jar file to be examined for classes 542 * @param urlPath the url of the jar file to be examined for classes 543 */ 544 private void loadImplementationsInJar(Test test, String parent, InputStream stream, String urlPath) { 545 JarInputStream jarStream = null; 546 try { 547 jarStream = new JarInputStream(stream); 548 549 JarEntry entry; 550 while ((entry = jarStream.getNextJarEntry()) != null) { 551 String name = entry.getName(); 552 if (name != null) { 553 name = name.trim(); 554 if (!entry.isDirectory() && name.startsWith(parent) && name.endsWith(".class")) { 555 addIfMatching(test, name); 556 } 557 } 558 } 559 } catch (IOException ioe) { 560 LOG.error("Could not search jar file '" + urlPath + "' for classes matching criteria: " + test 561 + " due to an IOException: " + ioe.getMessage(), ioe); 562 } finally { 563 ObjectHelper.close(jarStream, urlPath, LOG); 564 } 565 } 566 567 /** 568 * Add the class designated by the fully qualified class name provided to 569 * the set of resolved classes if and only if it is approved by the Test 570 * supplied. 571 * 572 * @param test the test used to determine if the class matches 573 * @param fqn the fully qualified name of a class 574 */ 575 protected void addIfMatching(Test test, String fqn) { 576 try { 577 String externalName = fqn.substring(0, fqn.indexOf('.')).replace('/', '.'); 578 Set<ClassLoader> set = getClassLoaders(); 579 boolean found = false; 580 for (ClassLoader classLoader : set) { 581 if (LOG.isTraceEnabled()) { 582 LOG.trace("Testing for class " + externalName + " matches criteria [" + test + "]"); 583 } 584 try { 585 Class type = classLoader.loadClass(externalName); 586 if (test.matches(type)) { 587 if (LOG.isTraceEnabled()) { 588 LOG.trace("Found class: " + type + " in classloader: " + classLoader); 589 } 590 matches.add((Class<T>)type); 591 } 592 found = true; 593 break; 594 } catch (ClassNotFoundException e) { 595 LOG.debug("Could not find class '" + fqn + "' in classloader: " + classLoader 596 + ". Reason: " + e, e); 597 } catch (NoClassDefFoundError e) { 598 LOG.debug("Could not find the class defintion '" + fqn + "' in classloader: " + classLoader 599 + ". Reason: " + e, e); 600 } 601 } 602 if (!found) { 603 LOG.warn("Could not find class '" + fqn + "' in any classloaders: " + set); 604 } 605 } catch (Throwable t) { 606 LOG.warn("Could not examine class '" + fqn + "' due to a " + t.getClass().getName() 607 + " with message: " + t.getMessage(), t); 608 } 609 } 610 611 }