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.logging.log4j.core.config.plugins;
018    
019    import org.apache.logging.log4j.Logger;
020    import org.apache.logging.log4j.core.helpers.Loader;
021    import org.apache.logging.log4j.status.StatusLogger;
022    import org.osgi.framework.FrameworkUtil;
023    import org.osgi.framework.wiring.BundleWiring;
024    
025    import java.io.File;
026    import java.io.FileInputStream;
027    import java.io.FileNotFoundException;
028    import java.io.IOException;
029    import java.lang.annotation.Annotation;
030    import java.net.URI;
031    import java.net.URL;
032    import java.net.URLDecoder;
033    import java.util.Collection;
034    import java.util.Enumeration;
035    import java.util.HashSet;
036    import java.util.Set;
037    import java.util.jar.JarEntry;
038    import java.util.jar.JarInputStream;
039    
040    /**
041     * <p>ResolverUtil is used to locate classes that are available in the/a class path and meet
042     * arbitrary conditions. The two most common conditions are that a class implements/extends
043     * another class, or that is it annotated with a specific annotation. However, through the use
044     * of the {@link Test} class it is possible to search using arbitrary conditions.</p>
045     *
046     * <p>A ClassLoader is used to locate all locations (directories and jar files) in the class
047     * path that contain classes within certain packages, and then to load those classes and
048     * check them. By default the ClassLoader returned by
049     *  {@code Thread.currentThread().getContextClassLoader()} is used, but this can be overridden
050     * by calling {@link #setClassLoader(ClassLoader)} prior to invoking any of the {@code find()}
051     * methods.</p>
052     *
053     * <p>General searches are initiated by calling the
054     * {@link #find(ResolverUtil.Test, String...)} method and supplying
055     * a package name and a Test instance. This will cause the named package <b>and all sub-packages</b>
056     * to be scanned for classes that meet the test. There are also utility methods for the common
057     * use cases of scanning multiple packages for extensions of particular classes, or classes
058     * annotated with a specific annotation.</p>
059     *
060     * <p>The standard usage pattern for the ResolverUtil class is as follows:</p>
061     *
062     *<pre>
063     *ResolverUtil&lt;ActionBean&gt; resolver = new ResolverUtil&lt;ActionBean&gt;();
064     *resolver.findImplementation(ActionBean.class, pkg1, pkg2);
065     *resolver.find(new CustomTest(), pkg1);
066     *resolver.find(new CustomTest(), pkg2);
067     *Collection&lt;ActionBean&gt; beans = resolver.getClasses();
068     *</pre>
069     *
070     * <p>This class was copied from Stripes - http://stripes.mc4j.org/confluence/display/stripes/Home
071     * </p>
072     *
073     * @author Tim Fennell
074     * @param <T> The type of the Class that can be returned.
075     */
076    public class ResolverUtil<T> {
077        /** An instance of Log to use for logging in this class. */
078        private static final Logger LOG = StatusLogger.getLogger();
079    
080        private static final String VFSZIP = "vfszip";
081    
082        private static final String BUNDLE_RESOURCE = "bundleresource";
083    
084        /** The set of matches being accumulated. */
085        private Set<Class<? extends T>> classMatches = new HashSet<Class<?extends T>>();
086    
087        /** The set of matches being accumulated. */
088        private Set<URI> resourceMatches = new HashSet<URI>();
089    
090        /**
091         * The ClassLoader to use when looking for classes. If null then the ClassLoader returned
092         * by Thread.currentThread().getContextClassLoader() will be used.
093         */
094        private ClassLoader classloader;
095    
096        /**
097         * Provides access to the classes discovered so far. If no calls have been made to
098         * any of the {@code find()} methods, this set will be empty.
099         *
100         * @return the set of classes that have been discovered.
101         */
102        public Set<Class<? extends T>> getClasses() {
103            return classMatches;
104        }
105    
106        /**
107         * Returns the matching resources.
108         * @return A Set of URIs that match the criteria.
109         */
110        public Set<URI> getResources() {
111            return resourceMatches;
112        }
113    
114    
115        /**
116         * Returns the classloader that will be used for scanning for classes. If no explicit
117         * ClassLoader has been set by the calling, the context class loader will be used.
118         *
119         * @return the ClassLoader that will be used to scan for classes
120         */
121        public ClassLoader getClassLoader() {
122            return classloader != null ? classloader : (classloader = Loader.getClassLoader(ResolverUtil.class, null));
123        }
124    
125        /**
126         * Sets an explicit ClassLoader that should be used when scanning for classes. If none
127         * is set then the context classloader will be used.
128         *
129         * @param classloader a ClassLoader to use when scanning for classes
130         */
131        public void setClassLoader(ClassLoader classloader) { this.classloader = classloader; }
132    
133        /**
134         * Attempts to discover classes that are assignable to the type provided. In the case
135         * that an interface is provided this method will collect implementations. In the case
136         * of a non-interface class, subclasses will be collected.  Accumulated classes can be
137         * accessed by calling {@link #getClasses()}.
138         *
139         * @param parent the class of interface to find subclasses or implementations of
140         * @param packageNames one or more package names to scan (including subpackages) for classes
141         */
142        public void findImplementations(Class parent, String... packageNames) {
143            if (packageNames == null) {
144                return;
145            }
146    
147            Test test = new IsA(parent);
148            for (String pkg : packageNames) {
149                findInPackage(test, pkg);
150            }
151        }
152    
153        /**
154         * Attempts to discover classes who's name ends with the provided suffix. Accumulated classes can be
155         * accessed by calling {@link #getClasses()}.
156         *
157         * @param suffix The class name suffix to match
158         * @param packageNames one or more package names to scan (including subpackages) for classes
159         */
160        public void findSuffix(String suffix, String... packageNames) {
161            if (packageNames == null) {
162                return;
163            }
164    
165            Test test = new NameEndsWith(suffix);
166            for (String pkg : packageNames) {
167                findInPackage(test, pkg);
168            }
169        }
170    
171        /**
172         * Attempts to discover classes that are annotated with to the annotation. Accumulated
173         * classes can be accessed by calling {@link #getClasses()}.
174         *
175         * @param annotation the annotation that should be present on matching classes
176         * @param packageNames one or more package names to scan (including subpackages) for classes
177         */
178        public void findAnnotated(Class<? extends Annotation> annotation, String... packageNames) {
179            if (packageNames == null) {
180                return;
181            }
182    
183            Test test = new AnnotatedWith(annotation);
184            for (String pkg : packageNames) {
185                findInPackage(test, pkg);
186            }
187        }
188    
189        public void findNamedResource(String name, String... pathNames) {
190            if (pathNames == null) {
191                return;
192            }
193    
194            Test test = new NameIs(name);
195            for (String pkg : pathNames) {
196                findInPackage(test, pkg);
197            }
198        }
199    
200        /**
201         * Attempts to discover classes that pass the test. Accumulated
202         * classes can be accessed by calling {@link #getClasses()}.
203         *
204         * @param test the test to determine matching classes
205         * @param packageNames one or more package names to scan (including subpackages) for classes
206         */
207        public void find(Test test, String... packageNames) {
208            if (packageNames == null) {
209                return;
210            }
211    
212            for (String pkg : packageNames) {
213                findInPackage(test, pkg);
214            }
215        }
216    
217        /**
218         * Scans for classes starting at the package provided and descending into subpackages.
219         * Each class is offered up to the Test as it is discovered, and if the Test returns
220         * true the class is retained.  Accumulated classes can be fetched by calling
221         * {@link #getClasses()}.
222         *
223         * @param test an instance of {@link Test} that will be used to filter classes
224         * @param packageName the name of the package from which to start scanning for
225         *        classes, e.g. {@code net.sourceforge.stripes}
226         */
227        public void findInPackage(Test test, String packageName) {
228            packageName = packageName.replace('.', '/');
229            ClassLoader loader = getClassLoader();
230            Enumeration<URL> urls;
231    
232            try {
233                urls = loader.getResources(packageName);
234            } catch (IOException ioe) {
235                LOG.warn("Could not read package: " + packageName, ioe);
236                return;
237            }
238    
239            while (urls.hasMoreElements()) {
240                try {
241                    URL url = urls.nextElement();
242                    String urlPath = url.getFile();
243                    urlPath = URLDecoder.decode(urlPath, "UTF-8");
244    
245                    // If it's a file in a directory, trim the stupid file: spec
246                    if (urlPath.startsWith("file:")) {
247                        urlPath = urlPath.substring(5);
248                    }
249    
250                    // Else it's in a JAR, grab the path to the jar
251                    if (urlPath.indexOf('!') > 0) {
252                        urlPath = urlPath.substring(0, urlPath.indexOf('!'));
253                    }
254    
255                    LOG.info("Scanning for classes in [" + urlPath + "] matching criteria: " + test);
256                    // Check for a jar in a war in JBoss
257                    if (VFSZIP.equals(url.getProtocol())) {
258                        String path = urlPath.substring(0, urlPath.length() - packageName.length() - 2);
259                        URL newURL = new URL(url.getProtocol(), url.getHost(), path);
260                        JarInputStream stream = new JarInputStream(newURL.openStream());
261                        loadImplementationsInJar(test, packageName, path, stream);
262                    } else if (BUNDLE_RESOURCE.equals(url.getProtocol())) {
263                        loadImplementationsInBundle(test, packageName);
264                    } else {
265                        File file = new File(urlPath);
266                        if (file.isDirectory()) {
267                            loadImplementationsInDirectory(test, packageName, file);
268                        } else {
269                            loadImplementationsInJar(test, packageName, file);
270                        }
271                    }
272                } catch (IOException ioe) {
273                    LOG.warn("could not read entries", ioe);
274                }
275            }
276        }
277    
278        private void loadImplementationsInBundle(Test test, String packageName) {
279            BundleWiring wiring = (BundleWiring)FrameworkUtil.getBundle(ResolverUtil.class).adapt(BundleWiring.class);
280            Collection<String> list = wiring.listResources(packageName, "*.class", BundleWiring.LISTRESOURCES_RECURSE);
281            for (String name : list) {
282                addIfMatching(test, name);
283            }
284        }
285    
286    
287        /**
288         * Finds matches in a physical directory on a filesystem.  Examines all
289         * files within a directory - if the File object is not a directory, and ends with <i>.class</i>
290         * the file is loaded and tested to see if it is acceptable according to the Test.  Operates
291         * recursively to find classes within a folder structure matching the package structure.
292         *
293         * @param test a Test used to filter the classes that are discovered
294         * @param parent the package name up to this directory in the package hierarchy.  E.g. if
295         *        /classes is in the classpath and we wish to examine files in /classes/org/apache then
296         *        the values of <i>parent</i> would be <i>org/apache</i>
297         * @param location a File object representing a directory
298         */
299        private void loadImplementationsInDirectory(Test test, String parent, File location) {
300            File[] files = location.listFiles();
301            StringBuilder builder;
302    
303            for (File file : files) {
304                builder = new StringBuilder();
305                builder.append(parent).append("/").append(file.getName());
306                String packageOrClass = parent == null ? file.getName() : builder.toString();
307    
308                if (file.isDirectory()) {
309                    loadImplementationsInDirectory(test, packageOrClass, file);
310                } else if (isTestApplicable(test, file.getName())) {
311                    addIfMatching(test, packageOrClass);
312                }
313            }
314        }
315    
316        private boolean isTestApplicable(Test test, String path) {
317            return test.doesMatchResource() || path.endsWith(".class") && test.doesMatchClass();
318        }
319    
320        /**
321         * Finds matching classes within a jar files that contains a folder structure
322         * matching the package structure.  If the File is not a JarFile or does not exist a warning
323         * will be logged, but no error will be raised.
324         *
325         * @param test a Test used to filter the classes that are discovered
326         * @param parent the parent package under which classes must be in order to be considered
327         * @param jarfile the jar file to be examined for classes
328         */
329        private void loadImplementationsInJar(Test test, String parent, File jarfile) {
330            JarInputStream jarStream;
331            try {
332                jarStream = new JarInputStream(new FileInputStream(jarfile));
333                loadImplementationsInJar(test, parent, jarfile.getPath(), jarStream);
334            } catch (FileNotFoundException ex) {
335                LOG.error("Could not search jar file '" + jarfile + "' for classes matching criteria: " +
336                    test + " file not found");
337            } catch (IOException ioe) {
338                LOG.error("Could not search jar file '" + jarfile + "' for classes matching criteria: " +
339                    test + " due to an IOException", ioe);
340            }
341        }
342    
343        /**
344         * Finds matching classes within a jar files that contains a folder structure
345         * matching the package structure.  If the File is not a JarFile or does not exist a warning
346         * will be logged, but no error will be raised.
347         *
348         * @param test a Test used to filter the classes that are discovered
349         * @param parent the parent package under which classes must be in order to be considered
350         * @param stream The jar InputStream
351         */
352        private void loadImplementationsInJar(Test test, String parent, String path, JarInputStream stream) {
353    
354            try {
355                JarEntry entry;
356    
357                while ((entry = stream.getNextJarEntry()) != null) {
358                    String name = entry.getName();
359                    if (!entry.isDirectory() && name.startsWith(parent) && isTestApplicable(test, name)) {
360                        addIfMatching(test, name);
361                    }
362                }
363            } catch (IOException ioe) {
364                LOG.error("Could not search jar file '" + path + "' for classes matching criteria: " +
365                    test + " due to an IOException", ioe);
366            }
367        }
368    
369        /**
370         * Add the class designated by the fully qualified class name provided to the set of
371         * resolved classes if and only if it is approved by the Test supplied.
372         *
373         * @param test the test used to determine if the class matches
374         * @param fqn the fully qualified name of a class
375         */
376        protected void addIfMatching(Test test, String fqn) {
377            try {
378                ClassLoader loader = getClassLoader();
379                if (test.doesMatchClass()) {
380                    String externalName = fqn.substring(0, fqn.indexOf('.')).replace('/', '.');
381                    if (LOG.isDebugEnabled()) {
382                        LOG.debug("Checking to see if class " + externalName + " matches criteria [" + test + "]");
383                    }
384    
385                    Class type = loader.loadClass(externalName);
386                    if (test.matches(type)) {
387                        classMatches.add(type);
388                    }
389                }
390                if (test.doesMatchResource()) {
391                    URL url = loader.getResource(fqn);
392                    if (url == null) {
393                        url = loader.getResource(fqn.substring(1));
394                    }
395                    if (url != null && test.matches(url.toURI())) {
396                        resourceMatches.add(url.toURI());
397                    }
398                }
399            } catch (Throwable t) {
400                LOG.warn("Could not examine class '" + fqn + "' due to a " +
401                    t.getClass().getName() + " with message: " + t.getMessage());
402            }
403        }
404    
405        /**
406         * A simple interface that specifies how to test classes to determine if they
407         * are to be included in the results produced by the ResolverUtil.
408         */
409        public interface Test {
410            /**
411             * Will be called repeatedly with candidate classes. Must return True if a class
412             * is to be included in the results, false otherwise.
413             * @param type The Class to match against.
414             * @return true if the Class matches.
415             */
416            boolean matches(Class type);
417    
418            /**
419             * Test for a resource.
420             * @param resource The URI to the resource.
421             * @return true if the resource matches.
422             */
423            boolean matches(URI resource);
424    
425            boolean doesMatchClass();
426            boolean doesMatchResource();
427        }
428    
429        /**
430         * Test against a Class.
431         */
432        public abstract static class ClassTest implements Test {
433            public boolean matches(URI resource) {
434                throw new UnsupportedOperationException();
435            }
436    
437            public boolean doesMatchClass() {
438                return true;
439            }
440            public boolean doesMatchResource() {
441                return false;
442            }
443        }
444    
445        /**
446         * Test against a resource.
447         */
448        public abstract static class ResourceTest implements Test {
449            public boolean matches(Class cls) {
450                throw new UnsupportedOperationException();
451            }
452    
453            public boolean doesMatchClass() {
454                return false;
455            }
456            public boolean doesMatchResource() {
457                return true;
458            }
459        }
460    
461        /**
462         * A Test that checks to see if each class is assignable to the provided class. Note
463         * that this test will match the parent type itself if it is presented for matching.
464         */
465        public static class IsA extends ClassTest {
466            private final Class parent;
467    
468            /**
469             * Constructs an IsA test using the supplied Class as the parent class/interface.
470             * @param parentType The parent class to check for.
471             */
472            public IsA(Class parentType) { this.parent = parentType; }
473    
474            /**
475             * Returns true if type is assignable to the parent type supplied in the constructor.
476             * @param type The Class to check.
477             * @return true if the Class matches.
478             */
479            public boolean matches(Class type) {
480                return type != null && parent.isAssignableFrom(type);
481            }
482    
483            @Override
484            public String toString() {
485                return "is assignable to " + parent.getSimpleName();
486            }
487        }
488    
489        /**
490         * A Test that checks to see if each class name ends with the provided suffix.
491         */
492        public static class NameEndsWith extends ClassTest {
493            private final String suffix;
494    
495            /**
496             * Constructs a NameEndsWith test using the supplied suffix.
497             * @param suffix the String suffix to check for.
498             */
499            public NameEndsWith(String suffix) { this.suffix = suffix; }
500    
501            /**
502             * Returns true if type name ends with the suffix supplied in the constructor.
503             * @param type The Class to check.
504             * @return true if the Class matches.
505             */
506            public boolean matches(Class type) {
507                return type != null && type.getName().endsWith(suffix);
508            }
509    
510            @Override
511            public String toString() {
512                return "ends with the suffix " + suffix;
513            }
514        }
515    
516        /**
517         * A Test that checks to see if each class is annotated with a specific annotation. If it
518         * is, then the test returns true, otherwise false.
519         */
520        public static class AnnotatedWith extends ClassTest {
521            private final Class<? extends Annotation> annotation;
522    
523            /**
524             * Constructs an AnnotatedWith test for the specified annotation type.
525             * @param annotation The annotation to check for.
526             */
527            public AnnotatedWith(Class<? extends Annotation> annotation) {
528                this.annotation = annotation;
529            }
530    
531            /**
532             * Returns true if the type is annotated with the class provided to the constructor.
533             * @param type the Class to match against.
534             * @return true if the Classes match.
535             */
536            public boolean matches(Class type) {
537                return type != null && type.isAnnotationPresent(annotation);
538            }
539    
540            @Override
541            public String toString() {
542                return "annotated with @" + annotation.getSimpleName();
543            }
544        }
545    
546        /**
547         * A Test that checks to see if the class name matches.
548         */
549        public static class NameIs extends ResourceTest {
550            private final String name;
551    
552            public NameIs(String name) { this.name = "/" + name; }
553    
554            public boolean matches(URI resource) {
555                return resource.getPath().endsWith(name);
556            }
557    
558            @Override public String toString() {
559                return "named " + name;
560            }
561        }
562    }