core/src/main/java/com/opensymphony/xwork2/util/ResolverUtil.java - struts - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *  http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */
 package com.opensymphony.xwork2.util;

 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.LogManager;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.lang.annotation.Annotation;
 import java.net.URL;
 import java.net.URLDecoder;
 import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.Set;
 import java.util.jar.JarEntry;
 import java.util.jar.JarInputStream;

 /**
  * <p>ResolverUtil is used to locate classes that are available in the/a class path and meet
  * arbitrary conditions. The two most common conditions are that a class implements/extends
  * another class, or that is it annotated with a specific annotation. However, through the use
  * of the {@link Test} class it is possible to search using arbitrary conditions.</p>
  *
  * <p>A ClassLoader is used to locate all locations (directories and jar files) in the class
  * path that contain classes within certain packages, and then to load those classes and
  * check them. By default the ClassLoader returned by
  *  {@code Thread.currentThread().getContextClassLoader()} is used, but this can be overridden
  * by calling {@link #setClassLoader(ClassLoader)} prior to invoking any of the {@code find()}
  * methods.</p>
  *
  * <p>General searches are initiated by calling the
  * {@link #find(com.opensymphony.xwork2.util.ResolverUtil.Test, String...)} ()} method and supplying
  * a package name and a Test instance. This will cause the named package <b>and all sub-packages</b>
  * to be scanned for classes that meet the test. There are also utility methods for the common
  * use cases of scanning multiple packages for extensions of particular classes, or classes
  * annotated with a specific annotation.</p>
  *
  * <p>The standard usage pattern for the ResolverUtil class is as follows:</p>
  *
  *<pre>
  *ResolverUtil&lt;ActionBean&gt; resolver = new ResolverUtil&lt;ActionBean&gt;();
  *resolver.findImplementation(ActionBean.class, pkg1, pkg2);
  *resolver.find(new CustomTest(), pkg1);
  *resolver.find(new CustomTest(), pkg2);
  *Collection&lt;ActionBean&gt; beans = resolver.getClasses();
  *</pre>
  *
  * <p>This class was copied from Stripes - http://stripes.mc4j.org/confluence/display/stripes/Home</p>
  *
  * @author Tim Fennell
  */
 public class ResolverUtil<T> {
     /** An instance of Log to use for logging in this class. */
     private static final Logger LOG = LogManager.getLogger(ResolverUtil.class);

     /**
      * A simple interface that specifies how to test classes to determine if they
      * are to be included in the results produced by the ResolverUtil.
      */
     public static interface Test {
         /**
          * Will be called repeatedly with candidate classes.
          *
          * @param type class type
          * @return True if a class is to be included in the results, false otherwise.
          */
         boolean matches(Class type);

         boolean matches(URL resource);

         boolean doesMatchClass();
         boolean doesMatchResource();
     }

     public static abstract class ClassTest implements Test {
         public boolean matches(URL resource) {
             throw new UnsupportedOperationException();
         }

         public boolean doesMatchClass() {
             return true;
         }
         public boolean doesMatchResource() {
             return false;
         }
     }

     public static abstract class ResourceTest implements Test {
         public boolean matches(Class cls) {
             throw new UnsupportedOperationException();
         }

         public boolean doesMatchClass() {
             return false;
         }
         public boolean doesMatchResource() {
             return true;
         }
     }

     /**
      * A Test that checks to see if each class is assignable to the provided class. Note
      * that this test will match the parent type itself if it is presented for matching.
      */
     public static class IsA extends ClassTest {
         private Class parent;

         /** Constructs an IsA test using the supplied Class as the parent class/interface.
          * @param parentType the parent type class
          */
         public IsA(Class parentType) { this.parent = parentType; }

         /**
          * @param type class type
          * @return true if type is assignable to the parent type supplied in the constructor.
          */
         public boolean matches(Class type) {
             return type != null && parent.isAssignableFrom(type);
         }

         @Override public String toString() {
             return "is assignable to " + parent.getSimpleName();
         }
     }

     /**
      * A Test that checks to see if each class name ends with the provided suffix.
      */
     public static class NameEndsWith extends ClassTest {
         private String suffix;

         /**
          * Constructs a NameEndsWith test using the supplied suffix.
          * @param suffix suffix
          */
         public NameEndsWith(String suffix) { this.suffix = suffix; }

         /**
          * @param type class type
          * @return true if type name ends with the suffix supplied in the constructor.
          */
         public boolean matches(Class type) {
             return type != null && type.getName().endsWith(suffix);
         }

         @Override public String toString() {
             return "ends with the suffix " + suffix;
         }
     }

     /**
      * A Test that checks to see if each class is annotated with a specific annotation. If it
      * is, then the test returns true, otherwise false.
      */
     public static class AnnotatedWith extends ClassTest {
         private Class<? extends Annotation> annotation;

         /**
          * Constructs an AnnotatedWith test for the specified annotation type.
          *
          * @param annotation annotation
          */
         public AnnotatedWith(Class<? extends Annotation> annotation) { this.annotation = annotation; }

         /**
          * @param type class type
          * @return true if the type is annotated with the class provided to the constructor.
          */
         public boolean matches(Class type) {
             return type != null && type.isAnnotationPresent(annotation);
         }

         @Override public String toString() {
             return "annotated with @" + annotation.getSimpleName();
         }
     }

     public static class NameIs extends ResourceTest {
         private String name;

         public NameIs(String name) { this.name = "/" + name; }

         public boolean matches(URL resource) {
             return (resource.getPath().endsWith(name));
         }

         @Override public String toString() {
             return "named " + name;
         }
     }

     /** The set of matches being accumulated. */
     private Set<Class<? extends T>> classMatches = new HashSet<Class<?extends T>>();

     /** The set of matches being accumulated. */
     private Set<URL> resourceMatches = new HashSet<>();

     /**
      * The ClassLoader to use when looking for classes. If null then the ClassLoader returned
      * by Thread.currentThread().getContextClassLoader() will be used.
      */
     private ClassLoader classloader;

     /**
      * Provides access to the classes discovered so far. If no calls have been made to
      * any of the {@code find()} methods, this set will be empty.
      *
      * @return the set of classes that have been discovered.
      */
     public Set<Class<? extends T>> getClasses() {
         return classMatches;
     }

     public Set<URL> getResources() {
         return resourceMatches;
     }


     /**
      * Returns the classloader that will be used for scanning for classes. If no explicit
      * ClassLoader has been set by the calling, the context class loader will be used.
      *
      * @return the ClassLoader that will be used to scan for classes
      */
     public ClassLoader getClassLoader() {
         return classloader == null ? Thread.currentThread().getContextClassLoader() : classloader;
     }

     /**
      * Sets an explicit ClassLoader that should be used when scanning for classes. If none
      * is set then the context classloader will be used.
      *
      * @param classloader a ClassLoader to use when scanning for classes
      */
     public void setClassLoader(ClassLoader classloader) { this.classloader = classloader; }

     /**
      * Attempts to discover classes that are assignable to the type provided. In the case
      * that an interface is provided this method will collect implementations. In the case
      * of a non-interface class, subclasses will be collected.  Accumulated classes can be
      * accessed by calling {@link #getClasses()}.
      *
      * @param parent the class of interface to find subclasses or implementations of
      * @param packageNames one or more package names to scan (including subpackages) for classes
      */
     public void findImplementations(Class parent, String... packageNames) {
         if (packageNames == null) return;

         Test test = new IsA(parent);
         for (String pkg : packageNames) {
             findInPackage(test, pkg);
         }
     }

     /**
      * Attempts to discover classes who's name ends with the provided suffix. Accumulated classes can be
      * accessed by calling {@link #getClasses()}.
      *
      * @param suffix The class name suffix to match
      * @param packageNames one or more package names to scan (including subpackages) for classes
      */
     public void findSuffix(String suffix, String... packageNames) {
         if (packageNames == null) return;

         Test test = new NameEndsWith(suffix);
         for (String pkg : packageNames) {
             findInPackage(test, pkg);
         }
     }

     /**
      * Attempts to discover classes that are annotated with to the annotation. Accumulated
      * classes can be accessed by calling {@link #getClasses()}.
      *
      * @param annotation the annotation that should be present on matching classes
      * @param packageNames one or more package names to scan (including subpackages) for classes
      */
     public void findAnnotated(Class<? extends Annotation> annotation, String... packageNames) {
         if (packageNames == null) return;

         Test test = new AnnotatedWith(annotation);
         for (String pkg : packageNames) {
             findInPackage(test, pkg);
         }
     }

     public void findNamedResource(String name, String... pathNames) {
         if (pathNames == null) return;

         Test test = new NameIs(name);
         for (String pkg : pathNames) {
             findInPackage(test, pkg);
         }
     }

     /**
      * Attempts to discover classes that pass the test. Accumulated
      * classes can be accessed by calling {@link #getClasses()}.
      *
      * @param test the test to determine matching classes
      * @param packageNames one or more package names to scan (including subpackages) for classes
      */
     public void find(Test test, String... packageNames) {
         if (packageNames == null) return;

         for (String pkg : packageNames) {
             findInPackage(test, pkg);
         }
     }

     /**
      * Scans for classes starting at the package provided and descending into subpackages.
      * Each class is offered up to the Test as it is discovered, and if the Test returns
      * true the class is retained.  Accumulated classes can be fetched by calling
      * {@link #getClasses()}.
      *
      * @param test an instance of {@link Test} that will be used to filter classes
      * @param packageName the name of the package from which to start scanning for
      *        classes, e.g. {@code net.sourceforge.stripes}
      */
     public void findInPackage(Test test, String packageName) {
         packageName = packageName.replace('.', '/');
         ClassLoader loader = getClassLoader();
         Enumeration<URL> urls;

         try {
             urls = loader.getResources(packageName);
         }
         catch (IOException ioe) {
             if (LOG.isWarnEnabled()) {
         	LOG.warn("Could not read package: " + packageName, ioe);
             }
             return;
         }

         while (urls.hasMoreElements()) {
             try {
                 String urlPath = urls.nextElement().getFile();
                 urlPath = URLDecoder.decode(urlPath, "UTF-8");

                 // If it's a file in a directory, trim the stupid file: spec
                 if ( urlPath.startsWith("file:") ) {
                     urlPath = urlPath.substring(5);
                 }

                 // Else it's in a JAR, grab the path to the jar
                 if (urlPath.indexOf('!') > 0) {
                     urlPath = urlPath.substring(0, urlPath.indexOf('!'));
                 }

                 if (LOG.isInfoEnabled()) {
                     LOG.info("Scanning for classes in [" + urlPath + "] matching criteria: " + test);
                 }
                 File file = new File(urlPath);
                 if ( file.isDirectory() ) {
                     loadImplementationsInDirectory(test, packageName, file);
                 }
                 else {
                     loadImplementationsInJar(test, packageName, file);
                 }
             }
             catch (IOException ioe) {
                 if (LOG.isWarnEnabled()) {
                     LOG.warn("could not read entries", ioe);
                 }
             }
         }
     }


     /**
      * Finds matches in a physical directory on a filesystem.  Examines all
      * files within a directory - if the File object is not a directory, and ends with <i>.class</i>
      * the file is loaded and tested to see if it is acceptable according to the Test.  Operates
      * recursively to find classes within a folder structure matching the package structure.
      *
      * @param test a Test used to filter the classes that are discovered
      * @param parent the package name up to this directory in the package hierarchy.  E.g. if
      *        /classes is in the classpath and we wish to examine files in /classes/org/apache then
      *        the values of <i>parent</i> would be <i>org/apache</i>
      * @param location a File object representing a directory
      */
     private void loadImplementationsInDirectory(Test test, String parent, File location) {
         File[] files = location.listFiles();
         StringBuilder builder = null;

         for (File file : files) {
             builder = new StringBuilder(100);
             builder.append(parent).append("/").append(file.getName());
             String packageOrClass = ( parent == null ? file.getName() : builder.toString() );

             if (file.isDirectory()) {
                 loadImplementationsInDirectory(test, packageOrClass, file);
             }
             else if (isTestApplicable(test, file.getName())) {
                 addIfMatching(test, packageOrClass);
             }
         }
     }

     private boolean isTestApplicable(Test test, String path) {
         return test.doesMatchResource() || path.endsWith(".class") && test.doesMatchClass();
     }

     /**
      * Finds matching classes within a jar files that contains a folder structure
      * matching the package structure.  If the File is not a JarFile or does not exist a warning
      * will be logged, but no error will be raised.
      *
      * @param test a Test used to filter the classes that are discovered
      * @param parent the parent package under which classes must be in order to be considered
      * @param jarfile the jar file to be examined for classes
      */
     private void loadImplementationsInJar(Test test, String parent, File jarfile) {

         try {
             JarEntry entry;
             JarInputStream jarStream = new JarInputStream(new FileInputStream(jarfile));

             while ( (entry = jarStream.getNextJarEntry() ) != null) {
                 String name = entry.getName();
                 if (!entry.isDirectory() && name.startsWith(parent) && isTestApplicable(test, name)) {
                     addIfMatching(test, name);
                 }
             }
         }
         catch (IOException ioe) {
             LOG.error("Could not search jar file '" + jarfile + "' for classes matching criteria: " +
                       test + " due to an IOException", ioe);
         }
     }

     /**
      * Add the class designated by the fully qualified class name provided to the set of
      * resolved classes if and only if it is approved by the Test supplied.
      *
      * @param test the test used to determine if the class matches
      * @param fqn the fully qualified name of a class
      */
     protected void addIfMatching(Test test, String fqn) {
         try {
             ClassLoader loader = getClassLoader();
             if (test.doesMatchClass()) {
                 String externalName = fqn.substring(0, fqn.indexOf('.')).replace('/', '.');
                 if (LOG.isDebugEnabled()) {
                     LOG.debug("Checking to see if class " + externalName + " matches criteria [" + test + "]");
                 }

                 Class type = loader.loadClass(externalName);
                 if (test.matches(type) ) {
                     classMatches.add( (Class<T>) type);
                 }
             }
             if (test.doesMatchResource()) {
                 URL url = loader.getResource(fqn);
                 if (url == null) {
                     url = loader.getResource(fqn.substring(1));
                 }
                 if (url != null && test.matches(url)) {
                     resourceMatches.add(url);
                 }
             }
         }
         catch (Throwable t) {
             if (LOG.isWarnEnabled()) {
         	LOG.warn("Could not examine class '" + fqn + "' due to a " +
                      t.getClass().getName() + " with message: " + t.getMessage());
             }
         }
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/
	package com.opensymphony.xwork2.util;

	import org.apache.logging.log4j.Logger;
	import org.apache.logging.log4j.LogManager;

	import java.io.File;
	import java.io.FileInputStream;
	import java.io.IOException;
	import java.lang.annotation.Annotation;
	import java.net.URL;
	import java.net.URLDecoder;
	import java.util.Enumeration;
	import java.util.HashSet;
	import java.util.Set;
	import java.util.jar.JarEntry;
	import java.util.jar.JarInputStream;

	/**
	* <p>ResolverUtil is used to locate classes that are available in the/a class path and meet
	* arbitrary conditions. The two most common conditions are that a class implements/extends
	* another class, or that is it annotated with a specific annotation. However, through the use
	* of the {@link Test} class it is possible to search using arbitrary conditions.</p>
	*
	* <p>A ClassLoader is used to locate all locations (directories and jar files) in the class
	* path that contain classes within certain packages, and then to load those classes and
	* check them. By default the ClassLoader returned by
	* {@code Thread.currentThread().getContextClassLoader()} is used, but this can be overridden
	* by calling {@link #setClassLoader(ClassLoader)} prior to invoking any of the {@code find()}
	* methods.</p>
	*
	* <p>General searches are initiated by calling the
	* {@link #find(com.opensymphony.xwork2.util.ResolverUtil.Test, String...)} ()} method and supplying
	* a package name and a Test instance. This will cause the named package <b>and all sub-packages</b>
	* to be scanned for classes that meet the test. There are also utility methods for the common
	* use cases of scanning multiple packages for extensions of particular classes, or classes
	* annotated with a specific annotation.</p>
	*
	* <p>The standard usage pattern for the ResolverUtil class is as follows:</p>
	*
	*<pre>
	*ResolverUtil<ActionBean> resolver = new ResolverUtil<ActionBean>();
	*resolver.findImplementation(ActionBean.class, pkg1, pkg2);
	*resolver.find(new CustomTest(), pkg1);
	*resolver.find(new CustomTest(), pkg2);
	*Collection<ActionBean> beans = resolver.getClasses();
	*</pre>
	*
	* <p>This class was copied from Stripes - http://stripes.mc4j.org/confluence/display/stripes/Home</p>
	*
	* @author Tim Fennell
	*/
	public class ResolverUtil<T> {
	/** An instance of Log to use for logging in this class. */
	private static final Logger LOG = LogManager.getLogger(ResolverUtil.class);

	/**
	* A simple interface that specifies how to test classes to determine if they
	* are to be included in the results produced by the ResolverUtil.
	*/
	public static interface Test {
	/**
	* Will be called repeatedly with candidate classes.
	*
	* @param type class type
	* @return True if a class is to be included in the results, false otherwise.
	*/
	boolean matches(Class type);

	boolean matches(URL resource);

	boolean doesMatchClass();
	boolean doesMatchResource();
	}

	public static abstract class ClassTest implements Test {
	public boolean matches(URL resource) {
	throw new UnsupportedOperationException();
	}

	public boolean doesMatchClass() {
	return true;
	}
	public boolean doesMatchResource() {
	return false;
	}
	}

	public static abstract class ResourceTest implements Test {
	public boolean matches(Class cls) {
	throw new UnsupportedOperationException();
	}

	public boolean doesMatchClass() {
	return false;
	}
	public boolean doesMatchResource() {
	return true;
	}
	}

	/**
	* A Test that checks to see if each class is assignable to the provided class. Note
	* that this test will match the parent type itself if it is presented for matching.
	*/
	public static class IsA extends ClassTest {
	private Class parent;

	/** Constructs an IsA test using the supplied Class as the parent class/interface.
	* @param parentType the parent type class
	*/
	public IsA(Class parentType) { this.parent = parentType; }

	/**
	* @param type class type
	* @return true if type is assignable to the parent type supplied in the constructor.
	*/
	public boolean matches(Class type) {
	return type != null && parent.isAssignableFrom(type);
	}

	@Override public String toString() {
	return "is assignable to " + parent.getSimpleName();
	}
	}

	/**
	* A Test that checks to see if each class name ends with the provided suffix.
	*/
	public static class NameEndsWith extends ClassTest {
	private String suffix;

	/**
	* Constructs a NameEndsWith test using the supplied suffix.
	* @param suffix suffix
	*/
	public NameEndsWith(String suffix) { this.suffix = suffix; }

	/**
	* @param type class type
	* @return true if type name ends with the suffix supplied in the constructor.
	*/
	public boolean matches(Class type) {
	return type != null && type.getName().endsWith(suffix);
	}

	@Override public String toString() {
	return "ends with the suffix " + suffix;
	}
	}

	/**
	* A Test that checks to see if each class is annotated with a specific annotation. If it
	* is, then the test returns true, otherwise false.
	*/
	public static class AnnotatedWith extends ClassTest {
	private Class<? extends Annotation> annotation;

	/**
	* Constructs an AnnotatedWith test for the specified annotation type.
	*
	* @param annotation annotation
	*/
	public AnnotatedWith(Class<? extends Annotation> annotation) { this.annotation = annotation; }

	/**
	* @param type class type
	* @return true if the type is annotated with the class provided to the constructor.
	*/
	public boolean matches(Class type) {
	return type != null && type.isAnnotationPresent(annotation);
	}

	@Override public String toString() {
	return "annotated with @" + annotation.getSimpleName();
	}
	}

	public static class NameIs extends ResourceTest {
	private String name;

	public NameIs(String name) { this.name = "/" + name; }

	public boolean matches(URL resource) {
	return (resource.getPath().endsWith(name));
	}

	@Override public String toString() {
	return "named " + name;
	}
	}

	/** The set of matches being accumulated. */
	private Set<Class<? extends T>> classMatches = new HashSet<Class<?extends T>>();

	/** The set of matches being accumulated. */
	private Set<URL> resourceMatches = new HashSet<>();

	/**
	* The ClassLoader to use when looking for classes. If null then the ClassLoader returned
	* by Thread.currentThread().getContextClassLoader() will be used.
	*/
	private ClassLoader classloader;

	/**
	* Provides access to the classes discovered so far. If no calls have been made to
	* any of the {@code find()} methods, this set will be empty.
	*
	* @return the set of classes that have been discovered.
	*/
	public Set<Class<? extends T>> getClasses() {
	return classMatches;
	}

	public Set<URL> getResources() {
	return resourceMatches;
	}


	/**
	* Returns the classloader that will be used for scanning for classes. If no explicit
	* ClassLoader has been set by the calling, the context class loader will be used.
	*
	* @return the ClassLoader that will be used to scan for classes
	*/
	public ClassLoader getClassLoader() {
	return classloader == null ? Thread.currentThread().getContextClassLoader() : classloader;
	}

	/**
	* Sets an explicit ClassLoader that should be used when scanning for classes. If none
	* is set then the context classloader will be used.
	*
	* @param classloader a ClassLoader to use when scanning for classes
	*/
	public void setClassLoader(ClassLoader classloader) { this.classloader = classloader; }

	/**
	* Attempts to discover classes that are assignable to the type provided. In the case
	* that an interface is provided this method will collect implementations. In the case
	* of a non-interface class, subclasses will be collected. Accumulated classes can be
	* accessed by calling {@link #getClasses()}.
	*
	* @param parent the class of interface to find subclasses or implementations of
	* @param packageNames one or more package names to scan (including subpackages) for classes
	*/
	public void findImplementations(Class parent, String... packageNames) {
	if (packageNames == null) return;

	Test test = new IsA(parent);
	for (String pkg : packageNames) {
	findInPackage(test, pkg);
	}
	}

	/**
	* Attempts to discover classes who's name ends with the provided suffix. Accumulated classes can be
	* accessed by calling {@link #getClasses()}.
	*
	* @param suffix The class name suffix to match
	* @param packageNames one or more package names to scan (including subpackages) for classes
	*/
	public void findSuffix(String suffix, String... packageNames) {
	if (packageNames == null) return;

	Test test = new NameEndsWith(suffix);
	for (String pkg : packageNames) {
	findInPackage(test, pkg);
	}
	}

	/**
	* Attempts to discover classes that are annotated with to the annotation. Accumulated
	* classes can be accessed by calling {@link #getClasses()}.
	*
	* @param annotation the annotation that should be present on matching classes
	* @param packageNames one or more package names to scan (including subpackages) for classes
	*/
	public void findAnnotated(Class<? extends Annotation> annotation, String... packageNames) {
	if (packageNames == null) return;

	Test test = new AnnotatedWith(annotation);
	for (String pkg : packageNames) {
	findInPackage(test, pkg);
	}
	}

	public void findNamedResource(String name, String... pathNames) {
	if (pathNames == null) return;

	Test test = new NameIs(name);
	for (String pkg : pathNames) {
	findInPackage(test, pkg);
	}
	}

	/**
	* Attempts to discover classes that pass the test. Accumulated
	* classes can be accessed by calling {@link #getClasses()}.
	*
	* @param test the test to determine matching classes
	* @param packageNames one or more package names to scan (including subpackages) for classes
	*/
	public void find(Test test, String... packageNames) {
	if (packageNames == null) return;

	for (String pkg : packageNames) {
	findInPackage(test, pkg);
	}
	}

	/**
	* Scans for classes starting at the package provided and descending into subpackages.
	* Each class is offered up to the Test as it is discovered, and if the Test returns
	* true the class is retained. Accumulated classes can be fetched by calling
	* {@link #getClasses()}.
	*
	* @param test an instance of {@link Test} that will be used to filter classes
	* @param packageName the name of the package from which to start scanning for
	* classes, e.g. {@code net.sourceforge.stripes}
	*/
	public void findInPackage(Test test, String packageName) {
	packageName = packageName.replace('.', '/');
	ClassLoader loader = getClassLoader();
	Enumeration<URL> urls;

	try {
	urls = loader.getResources(packageName);
	}
	catch (IOException ioe) {
	if (LOG.isWarnEnabled()) {
	LOG.warn("Could not read package: " + packageName, ioe);
	}
	return;
	}

	while (urls.hasMoreElements()) {
	try {
	String urlPath = urls.nextElement().getFile();
	urlPath = URLDecoder.decode(urlPath, "UTF-8");

	// If it's a file in a directory, trim the stupid file: spec
	if ( urlPath.startsWith("file:") ) {
	urlPath = urlPath.substring(5);
	}

	// Else it's in a JAR, grab the path to the jar
	if (urlPath.indexOf('!') > 0) {
	urlPath = urlPath.substring(0, urlPath.indexOf('!'));
	}

	if (LOG.isInfoEnabled()) {
	LOG.info("Scanning for classes in [" + urlPath + "] matching criteria: " + test);
	}
	File file = new File(urlPath);
	if ( file.isDirectory() ) {
	loadImplementationsInDirectory(test, packageName, file);
	}
	else {
	loadImplementationsInJar(test, packageName, file);
	}
	}
	catch (IOException ioe) {
	if (LOG.isWarnEnabled()) {
	LOG.warn("could not read entries", ioe);
	}
	}
	}
	}


	/**
	* Finds matches in a physical directory on a filesystem. Examines all
	* files within a directory - if the File object is not a directory, and ends with <i>.class</i>
	* the file is loaded and tested to see if it is acceptable according to the Test. Operates
	* recursively to find classes within a folder structure matching the package structure.
	*
	* @param test a Test used to filter the classes that are discovered
	* @param parent the package name up to this directory in the package hierarchy. E.g. if
	* /classes is in the classpath and we wish to examine files in /classes/org/apache then
	* the values of <i>parent</i> would be <i>org/apache</i>
	* @param location a File object representing a directory
	*/
	private void loadImplementationsInDirectory(Test test, String parent, File location) {
	File[] files = location.listFiles();
	StringBuilder builder = null;

	for (File file : files) {
	builder = new StringBuilder(100);
	builder.append(parent).append("/").append(file.getName());
	String packageOrClass = ( parent == null ? file.getName() : builder.toString() );

	if (file.isDirectory()) {
	loadImplementationsInDirectory(test, packageOrClass, file);
	}
	else if (isTestApplicable(test, file.getName())) {
	addIfMatching(test, packageOrClass);
	}
	}
	}

	private boolean isTestApplicable(Test test, String path) {
	return test.doesMatchResource() \|\| path.endsWith(".class") && test.doesMatchClass();
	}

	/**
	* Finds matching classes within a jar files that contains a folder structure
	* matching the package structure. If the File is not a JarFile or does not exist a warning
	* will be logged, but no error will be raised.
	*
	* @param test a Test used to filter the classes that are discovered
	* @param parent the parent package under which classes must be in order to be considered
	* @param jarfile the jar file to be examined for classes
	*/
	private void loadImplementationsInJar(Test test, String parent, File jarfile) {

	try {
	JarEntry entry;
	JarInputStream jarStream = new JarInputStream(new FileInputStream(jarfile));

	while ( (entry = jarStream.getNextJarEntry() ) != null) {
	String name = entry.getName();
	if (!entry.isDirectory() && name.startsWith(parent) && isTestApplicable(test, name)) {
	addIfMatching(test, name);
	}
	}
	}
	catch (IOException ioe) {
	LOG.error("Could not search jar file '" + jarfile + "' for classes matching criteria: " +
	test + " due to an IOException", ioe);
	}
	}

	/**
	* Add the class designated by the fully qualified class name provided to the set of
	* resolved classes if and only if it is approved by the Test supplied.
	*
	* @param test the test used to determine if the class matches
	* @param fqn the fully qualified name of a class
	*/
	protected void addIfMatching(Test test, String fqn) {
	try {
	ClassLoader loader = getClassLoader();
	if (test.doesMatchClass()) {
	String externalName = fqn.substring(0, fqn.indexOf('.')).replace('/', '.');
	if (LOG.isDebugEnabled()) {
	LOG.debug("Checking to see if class " + externalName + " matches criteria [" + test + "]");
	}

	Class type = loader.loadClass(externalName);
	if (test.matches(type) ) {
	classMatches.add( (Class<T>) type);
	}
	}
	if (test.doesMatchResource()) {
	URL url = loader.getResource(fqn);
	if (url == null) {
	url = loader.getResource(fqn.substring(1));
	}
	if (url != null && test.matches(url)) {
	resourceMatches.add(url);
	}
	}
	}
	catch (Throwable t) {
	if (LOG.isWarnEnabled()) {
	LOG.warn("Could not examine class '" + fqn + "' due to a " +
	t.getClass().getName() + " with message: " + t.getMessage());
	}
	}
	}
	}