/*
    * Copyright 2002-2014 the original author or authors.
    *
    * Licensed 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 org.springframework.core.io.support;
  
  import java.io.File;
  import java.io.IOException;
  import java.lang.reflect.InvocationHandler;
  import java.lang.reflect.Method;
  import java.net.JarURLConnection;
  import java.net.MalformedURLException;
  import java.net.URISyntaxException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.net.URLConnection;
  import java.util.Collections;
  import java.util.Enumeration;
  import java.util.LinkedHashSet;
  import java.util.Set;
  import java.util.jar.JarEntry;
  import java.util.jar.JarFile;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.springframework.core.io.DefaultResourceLoader;
  import org.springframework.core.io.FileSystemResource;
  import org.springframework.core.io.Resource;
  import org.springframework.core.io.ResourceLoader;
  import org.springframework.core.io.UrlResource;
  import org.springframework.core.io.VfsResource;
  import org.springframework.util.AntPathMatcher;
  import org.springframework.util.Assert;
  import org.springframework.util.ClassUtils;
  import org.springframework.util.PathMatcher;
  import org.springframework.util.ReflectionUtils;
  import org.springframework.util.ResourceUtils;
  import org.springframework.util.StringUtils;
  
  /**
   * A {@link ResourcePatternResolver} implementation that is able to resolve a
   * specified resource location path into one or more matching Resources.
   * The source path may be a simple path which has a one-to-one mapping to a
   * target {@link org.springframework.core.io.Resource}, or alternatively
   * may contain the special "{@code classpath*:}" prefix and/or
   * internal Ant-style regular expressions (matched using Spring's
   * {@link org.springframework.util.AntPathMatcher} utility).
   * Both of the latter are effectively wildcards.
   *
   * <p><b>No Wildcards:</b>
   *
   * <p>In the simple case, if the specified location path does not start with the
   * {@code "classpath*:}" prefix, and does not contain a PathMatcher pattern,
   * this resolver will simply return a single resource via a
   * {@code getResource()} call on the underlying {@code ResourceLoader}.
   * Examples are real URLs such as "{@code file:C:/context.xml}", pseudo-URLs
   * such as "{@code classpath:/context.xml}", and simple unprefixed paths
   * such as "{@code /WEB-INF/context.xml}". The latter will resolve in a
   * fashion specific to the underlying {@code ResourceLoader} (e.g.
   * {@code ServletContextResource} for a {@code WebApplicationContext}).
   *
   * <p><b>Ant-style Patterns:</b>
   *
   * <p>When the path location contains an Ant-style pattern, e.g.:
   * <pre class="code">
   * /WEB-INF/*-context.xml
   * com/mycompany/**&#47;applicationContext.xml
   * file:C:/some/path/*-context.xml
   * classpath:com/mycompany/**&#47;applicationContext.xml</pre>
   * the resolver follows a more complex but defined procedure to try to resolve
   * the wildcard. It produces a {@code Resource} for the path up to the last
   * non-wildcard segment and obtains a {@code URL} from it. If this URL is
   * not a "{@code jar:}" URL or container-specific variant (e.g.
   * "{@code zip:}" in WebLogic, "{@code wsjar}" in WebSphere", etc.),
   * then a {@code java.io.File} is obtained from it, and used to resolve the
   * wildcard by walking the filesystem. In the case of a jar URL, the resolver
   * either gets a {@code java.net.JarURLConnection} from it, or manually parses
   * the jar URL, and then traverses the contents of the jar file, to resolve the
   * wildcards.
   *
   * <p><b>Implications on portability:</b>
   *
   * <p>If the specified path is already a file URL (either explicitly, or
   * implicitly because the base {@code ResourceLoader} is a filesystem one,
   * then wildcarding is guaranteed to work in a completely portable fashion.
   *
  * <p>If the specified path is a classpath location, then the resolver must
  * obtain the last non-wildcard path segment URL via a
  * {@code Classloader.getResource()} call. Since this is just a
  * node of the path (not the file at the end) it is actually undefined
  * (in the ClassLoader Javadocs) exactly what sort of a URL is returned in
  * this case. In practice, it is usually a {@code java.io.File} representing
  * the directory, where the classpath resource resolves to a filesystem
  * location, or a jar URL of some sort, where the classpath resource resolves
  * to a jar location. Still, there is a portability concern on this operation.
  *
  * <p>If a jar URL is obtained for the last non-wildcard segment, the resolver
  * must be able to get a {@code java.net.JarURLConnection} from it, or
  * manually parse the jar URL, to be able to walk the contents of the jar,
  * and resolve the wildcard. This will work in most environments, but will
  * fail in others, and it is strongly recommended that the wildcard
  * resolution of resources coming from jars be thoroughly tested in your
  * specific environment before you rely on it.
  *
  * <p><b>{@code classpath*:} Prefix:</b>
  *
  * <p>There is special support for retrieving multiple class path resources with
  * the same name, via the "{@code classpath*:}" prefix. For example,
  * "{@code classpath*:META-INF/beans.xml}" will find all "beans.xml"
  * files in the class path, be it in "classes" directories or in JAR files.
  * This is particularly useful for autodetecting config files of the same name
  * at the same location within each jar file. Internally, this happens via a
  * {@code ClassLoader.getResources()} call, and is completely portable.
  *
  * <p>The "classpath*:" prefix can also be combined with a PathMatcher pattern in
  * the rest of the location path, for example "classpath*:META-INF/*-beans.xml".
  * In this case, the resolution strategy is fairly simple: a
  * {@code ClassLoader.getResources()} call is used on the last non-wildcard
  * path segment to get all the matching resources in the class loader hierarchy,
  * and then off each resource the same PathMatcher resolution strategy described
  * above is used for the wildcard subpath.
  *
  * <p><b>Other notes:</b>
  *
  * <p><b>WARNING:</b> Note that "{@code classpath*:}" when combined with
  * Ant-style patterns will only work reliably with at least one root directory
  * before the pattern starts, unless the actual target files reside in the file
  * system. This means that a pattern like "{@code classpath*:*.xml}" will
  * <i>not</i> retrieve files from the root of jar files but rather only from the
  * root of expanded directories. This originates from a limitation in the JDK's
  * {@code ClassLoader.getResources()} method which only returns file system
  * locations for a passed-in empty String (indicating potential roots to search).
  *
  * <p><b>WARNING:</b> Ant-style patterns with "classpath:" resources are not
  * guaranteed to find matching resources if the root package to search is available
  * in multiple class path locations. This is because a resource such as
  * <pre class="code">
  *     com/mycompany/package1/service-context.xml
  * </pre>
  * may be in only one location, but when a path such as
  * <pre class="code">
  *     classpath:com/mycompany/**&#47;service-context.xml
  * </pre>
  * is used to try to resolve it, the resolver will work off the (first) URL
  * returned by {@code getResource("com/mycompany");}. If this base package
  * node exists in multiple classloader locations, the actual end resource may
  * not be underneath. Therefore, preferably, use "{@code classpath*:}" with the same
  * Ant-style pattern in such a case, which will search <i>all</i> class path
  * locations that contain the root package.
  *
  * @author Juergen Hoeller
  * @author Colin Sampaleanu
  * @author Marius Bogoevici
  * @author Costin Leau
  * @since 1.0.2
  * @see #CLASSPATH_ALL_URL_PREFIX
  * @see org.springframework.util.AntPathMatcher
  * @see org.springframework.core.io.ResourceLoader#getResource(String)
  * @see ClassLoader#getResources(String)
  */
 public class PathMatchingResourcePatternResolver implements ResourcePatternResolver {
 
 	private static final Log logger = LogFactory.getLog(PathMatchingResourcePatternResolver.class);
 
 	private static Method equinoxResolveMethod;
 
 	static {
 		try {
 			// Detect Equinox OSGi (e.g. on WebSphere 6.1)
 			Class<?> fileLocatorClass = ClassUtils.forName("org.eclipse.core.runtime.FileLocator",
 					PathMatchingResourcePatternResolver.class.getClassLoader());
 			equinoxResolveMethod = fileLocatorClass.getMethod("resolve", URL.class);
 			logger.debug("Found Equinox FileLocator for OSGi bundle URL resolution");
 		}
 		catch (Throwable ex) {
 			equinoxResolveMethod = null;
 		}
 	}
 
 
 	private final ResourceLoader resourceLoader;
 
 	private PathMatcher pathMatcher = new AntPathMatcher();
 
 
 	/**
 	 * Create a new PathMatchingResourcePatternResolver with a DefaultResourceLoader.
 	 * <p>ClassLoader access will happen via the thread context class loader.
 	 * @see org.springframework.core.io.DefaultResourceLoader
 	 */
 	public PathMatchingResourcePatternResolver() {
 		this.resourceLoader = new DefaultResourceLoader();
 	}
 
 	/**
 	 * Create a new PathMatchingResourcePatternResolver.
 	 * <p>ClassLoader access will happen via the thread context class loader.
 	 * @param resourceLoader the ResourceLoader to load root directories and
 	 * actual resources with
 	 */
 	public PathMatchingResourcePatternResolver(ResourceLoader resourceLoader) {
 		Assert.notNull(resourceLoader, "ResourceLoader must not be null");
 		this.resourceLoader = resourceLoader;
 	}
 
 	/**
 	 * Create a new PathMatchingResourcePatternResolver with a DefaultResourceLoader.
 	 * @param classLoader the ClassLoader to load classpath resources with,
 	 * or {@code null} for using the thread context class loader
 	 * at the time of actual resource access
 	 * @see org.springframework.core.io.DefaultResourceLoader
 	 */
 	public PathMatchingResourcePatternResolver(ClassLoader classLoader) {
 		this.resourceLoader = new DefaultResourceLoader(classLoader);
 	}
 
 
 	/**
 	 * Return the ResourceLoader that this pattern resolver works with.
 	 */
 	public ResourceLoader getResourceLoader() {
 		return this.resourceLoader;
 	}
 
 	@Override
 	public ClassLoader getClassLoader() {
 		return getResourceLoader().getClassLoader();
 	}
 
 	/**
 	 * Set the PathMatcher implementation to use for this
 	 * resource pattern resolver. Default is AntPathMatcher.
 	 * @see org.springframework.util.AntPathMatcher
 	 */
 	public void setPathMatcher(PathMatcher pathMatcher) {
 		Assert.notNull(pathMatcher, "PathMatcher must not be null");
 		this.pathMatcher = pathMatcher;
 	}
 
 	/**
 	 * Return the PathMatcher that this resource pattern resolver uses.
 	 */
 	public PathMatcher getPathMatcher() {
 		return this.pathMatcher;
 	}
 
 
 	@Override
 	public Resource getResource(String location) {
 		return getResourceLoader().getResource(location);
 	}
 
 	@Override
 	public Resource[] getResources(String locationPattern) throws IOException {
 		Assert.notNull(locationPattern, "Location pattern must not be null");
 		if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
 			// a class path resource (multiple resources for same name possible)
 			if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
 				// a class path resource pattern
 				return findPathMatchingResources(locationPattern);
 			}
 			else {
 				// all class path resources with the given name
 				return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
 			}
 		}
 		else {
 			// Only look for a pattern after a prefix here
 			// (to not get fooled by a pattern symbol in a strange prefix).
 			int prefixEnd = locationPattern.indexOf(":") + 1;
 			if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
 				// a file pattern
 				return findPathMatchingResources(locationPattern);
 			}
 			else {
 				// a single resource with the given name
 				return new Resource[] {getResourceLoader().getResource(locationPattern)};
 			}
 		}
 	}
 
 	/**
 	 * Find all class location resources with the given location via the ClassLoader.
 	 * Delegates to {@link #doFindAllClassPathResources(String)}.
 	 * @param location the absolute path within the classpath
 	 * @return the result as Resource array
 	 * @throws IOException in case of I/O errors
 	 * @see java.lang.ClassLoader#getResources
 	 * @see #convertClassLoaderURL
 	 */
 	protected Resource[] findAllClassPathResources(String location) throws IOException {
 		String path = location;
 		if (path.startsWith("/")) {
 			path = path.substring(1);
 		}
 		Set<Resource> result = doFindAllClassPathResources(path);
 		return result.toArray(new Resource[result.size()]);
 	}
 
 	/**
 	 * Find all class location resources with the given path via the ClassLoader.
 	 * Called by {@link #findAllClassPathResources(String)}.
 	 * @param path the absolute path within the classpath (never a leading slash)
 	 * @return a mutable Set of matching Resource instances
 	 */
 	protected Set<Resource> doFindAllClassPathResources(String path) throws IOException {
 		Set<Resource> result = new LinkedHashSet<Resource>(16);
 		ClassLoader cl = getClassLoader();
 		Enumeration<URL> resourceUrls = (cl != null ? cl.getResources(path) : ClassLoader.getSystemResources(path));
 		while (resourceUrls.hasMoreElements()) {
 			URL url = resourceUrls.nextElement();
 			result.add(convertClassLoaderURL(url));
 		}
 		if ("".equals(path)) {
 			// The above result is likely to be incomplete, i.e. only containing file system references.
 			// We need to have pointers to each of the jar files on the classpath as well...
 			addAllClassLoaderJarRoots(cl, result);
 		}
 		return result;
 	}
 
 	/**
 	 * Convert the given URL as returned from the ClassLoader into a {@link Resource}.
 	 * <p>The default implementation simply creates a {@link UrlResource} instance.
 	 * @param url a URL as returned from the ClassLoader
 	 * @return the corresponding Resource object
 	 * @see java.lang.ClassLoader#getResources
 	 * @see org.springframework.core.io.Resource
 	 */
 	protected Resource convertClassLoaderURL(URL url) {
 		return new UrlResource(url);
 	}
 
 	/**
 	 * Search all {@link URLClassLoader} URLs for jar file references and add them to the
 	 * given set of resources in the form of pointers to the root of the jar file content.
 	 * @param classLoader the ClassLoader to search (including its ancestors)
 	 * @param result the set of resources to add jar roots to
 	 */
 	protected void addAllClassLoaderJarRoots(ClassLoader classLoader, Set<Resource> result) {
 		if (classLoader instanceof URLClassLoader) {
 			try {
 				for (URL url : ((URLClassLoader) classLoader).getURLs()) {
 					if (ResourceUtils.isJarFileURL(url)) {
 						try {
 							UrlResource jarResource = new UrlResource(
 									ResourceUtils.JAR_URL_PREFIX + url.toString() + ResourceUtils.JAR_URL_SEPARATOR);
 							if (jarResource.exists()) {
 								result.add(jarResource);
 							}
 						}
 						catch (MalformedURLException ex) {
 							if (logger.isDebugEnabled()) {
 								logger.debug("Cannot search for matching files underneath [" + url +
 										"] because it cannot be converted to a valid 'jar:' URL: " + ex.getMessage());
 							}
 						}
 					}
 				}
 			}
 			catch (Exception ex) {
 				if (logger.isDebugEnabled()) {
 					logger.debug("Cannot introspect jar files since ClassLoader [" + classLoader +
 							"] does not support 'getURLs()': " + ex);
 				}
 			}
 		}
 		if (classLoader != null) {
 			try {
 				addAllClassLoaderJarRoots(classLoader.getParent(), result);
 			}
 			catch (Exception ex) {
 				if (logger.isDebugEnabled()) {
 					logger.debug("Cannot introspect jar files in parent ClassLoader since [" + classLoader +
 							"] does not support 'getParent()': " + ex);
 				}
 			}
 		}
 	}
 
 	/**
 	 * Find all resources that match the given location pattern via the
 	 * Ant-style PathMatcher. Supports resources in jar files and zip files
 	 * and in the file system.
 	 * @param locationPattern the location pattern to match
 	 * @return the result as Resource array
 	 * @throws IOException in case of I/O errors
 	 * @see #doFindPathMatchingJarResources
 	 * @see #doFindPathMatchingFileResources
 	 * @see org.springframework.util.PathMatcher
 	 */
 	protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
 		String rootDirPath = determineRootDir(locationPattern);
 		String subPattern = locationPattern.substring(rootDirPath.length());
 		Resource[] rootDirResources = getResources(rootDirPath);
 		Set<Resource> result = new LinkedHashSet<Resource>(16);
 		for (Resource rootDirResource : rootDirResources) {
 			rootDirResource = resolveRootDirResource(rootDirResource);
 			if (rootDirResource.getURL().getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
 				result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirResource, subPattern, getPathMatcher()));
 			}
 			else if (isJarResource(rootDirResource)) {
 				result.addAll(doFindPathMatchingJarResources(rootDirResource, subPattern));
 			}
 			else {
 				result.addAll(doFindPathMatchingFileResources(rootDirResource, subPattern));
 			}
 		}
 		if (logger.isDebugEnabled()) {
 			logger.debug("Resolved location pattern [" + locationPattern + "] to resources " + result);
 		}
 		return result.toArray(new Resource[result.size()]);
 	}
 
 	/**
 	 * Determine the root directory for the given location.
 	 * <p>Used for determining the starting point for file matching,
 	 * resolving the root directory location to a {@code java.io.File}
 	 * and passing it into {@code retrieveMatchingFiles}, with the
 	 * remainder of the location as pattern.
 	 * <p>Will return "/WEB-INF/" for the pattern "/WEB-INF/*.xml",
 	 * for example.
 	 * @param location the location to check
 	 * @return the part of the location that denotes the root directory
 	 * @see #retrieveMatchingFiles
 	 */
 	protected String determineRootDir(String location) {
 		int prefixEnd = location.indexOf(":") + 1;
 		int rootDirEnd = location.length();
 		while (rootDirEnd > prefixEnd && getPathMatcher().isPattern(location.substring(prefixEnd, rootDirEnd))) {
 			rootDirEnd = location.lastIndexOf('/', rootDirEnd - 2) + 1;
 		}
 		if (rootDirEnd == 0) {
 			rootDirEnd = prefixEnd;
 		}
 		return location.substring(0, rootDirEnd);
 	}
 
 	/**
 	 * Resolve the specified resource for path matching.
 	 * <p>The default implementation detects an Equinox OSGi "bundleresource:"
 	 * / "bundleentry:" URL and resolves it into a standard jar file URL that
 	 * can be traversed using Spring's standard jar file traversal algorithm.
 	 * @param original the resource to resolve
 	 * @return the resolved resource (may be identical to the passed-in resource)
 	 * @throws IOException in case of resolution failure
 	 */
 	protected Resource resolveRootDirResource(Resource original) throws IOException {
 		if (equinoxResolveMethod != null) {
 			URL url = original.getURL();
 			if (url.getProtocol().startsWith("bundle")) {
 				return new UrlResource((URL) ReflectionUtils.invokeMethod(equinoxResolveMethod, null, url));
 			}
 		}
 		return original;
 	}
 
 	/**
 	 * Return whether the given resource handle indicates a jar resource
 	 * that the {@code doFindPathMatchingJarResources} method can handle.
 	 * <p>The default implementation checks against the URL protocols
 	 * "jar", "zip" and "wsjar" (the latter are used by BEA WebLogic Server
 	 * and IBM WebSphere, respectively, but can be treated like jar files).
 	 * @param resource the resource handle to check
 	 * (usually the root directory to start path matching from)
 	 * @see #doFindPathMatchingJarResources
 	 * @see org.springframework.util.ResourceUtils#isJarURL
 	 */
 	protected boolean isJarResource(Resource resource) throws IOException {
 		return ResourceUtils.isJarURL(resource.getURL());
 	}
 
 	/**
 	 * Find all resources in jar files that match the given location pattern
 	 * via the Ant-style PathMatcher.
 	 * @param rootDirResource the root directory as Resource
 	 * @param subPattern the sub pattern to match (below the root directory)
 	 * @return a mutable Set of matching Resource instances
 	 * @throws IOException in case of I/O errors
 	 * @see java.net.JarURLConnection
 	 * @see org.springframework.util.PathMatcher
 	 */
 	protected Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource, String subPattern)
 			throws IOException {
 
 		URLConnection con = rootDirResource.getURL().openConnection();
 		JarFile jarFile;
 		String jarFileUrl;
 		String rootEntryPath;
 		boolean newJarFile = false;
 
 		if (con instanceof JarURLConnection) {
 			// Should usually be the case for traditional JAR files.
 			JarURLConnection jarCon = (JarURLConnection) con;
 			ResourceUtils.useCachesIfNecessary(jarCon);
 			jarFile = jarCon.getJarFile();
 			jarFileUrl = jarCon.getJarFileURL().toExternalForm();
 			JarEntry jarEntry = jarCon.getJarEntry();
 			rootEntryPath = (jarEntry != null ? jarEntry.getName() : "");
 		}
 		else {
 			// No JarURLConnection -> need to resort to URL file parsing.
 			// We'll assume URLs of the format "jar:path!/entry", with the protocol
 			// being arbitrary as long as following the entry format.
 			// We'll also handle paths with and without leading "file:" prefix.
 			String urlFile = rootDirResource.getURL().getFile();
 			int separatorIndex = urlFile.indexOf(ResourceUtils.JAR_URL_SEPARATOR);
 			if (separatorIndex != -1) {
 				jarFileUrl = urlFile.substring(0, separatorIndex);
 				rootEntryPath = urlFile.substring(separatorIndex + ResourceUtils.JAR_URL_SEPARATOR.length());
 				jarFile = getJarFile(jarFileUrl);
 			}
 			else {
 				jarFile = new JarFile(urlFile);
 				jarFileUrl = urlFile;
 				rootEntryPath = "";
 			}
 			newJarFile = true;
 		}
 
 		try {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Looking for matching resources in jar file [" + jarFileUrl + "]");
 			}
 			if (!"".equals(rootEntryPath) && !rootEntryPath.endsWith("/")) {
 				// Root entry path must end with slash to allow for proper matching.
 				// The Sun JRE does not return a slash here, but BEA JRockit does.
 				rootEntryPath = rootEntryPath + "/";
 			}
 			Set<Resource> result = new LinkedHashSet<Resource>(8);
 			for (Enumeration<JarEntry> entries = jarFile.entries(); entries.hasMoreElements();) {
 				JarEntry entry = entries.nextElement();
 				String entryPath = entry.getName();
 				if (entryPath.startsWith(rootEntryPath)) {
 					String relativePath = entryPath.substring(rootEntryPath.length());
 					if (getPathMatcher().match(subPattern, relativePath)) {
 						result.add(rootDirResource.createRelative(relativePath));
 					}
 				}
 			}
 			return result;
 		}
 		finally {
 			// Close jar file, but only if freshly obtained -
 			// not from JarURLConnection, which might cache the file reference.
 			if (newJarFile) {
 				jarFile.close();
 			}
 		}
 	}
 
 	/**
 	 * Resolve the given jar file URL into a JarFile object.
 	 */
 	protected JarFile getJarFile(String jarFileUrl) throws IOException {
 		if (jarFileUrl.startsWith(ResourceUtils.FILE_URL_PREFIX)) {
 			try {
 				return new JarFile(ResourceUtils.toURI(jarFileUrl).getSchemeSpecificPart());
 			}
 			catch (URISyntaxException ex) {
 				// Fallback for URLs that are not valid URIs (should hardly ever happen).
 				return new JarFile(jarFileUrl.substring(ResourceUtils.FILE_URL_PREFIX.length()));
 			}
 		}
 		else {
 			return new JarFile(jarFileUrl);
 		}
 	}
 
 	/**
 	 * Find all resources in the file system that match the given location pattern
 	 * via the Ant-style PathMatcher.
 	 * @param rootDirResource the root directory as Resource
 	 * @param subPattern the sub pattern to match (below the root directory)
 	 * @return a mutable Set of matching Resource instances
 	 * @throws IOException in case of I/O errors
 	 * @see #retrieveMatchingFiles
 	 * @see org.springframework.util.PathMatcher
 	 */
 	protected Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource, String subPattern)
 			throws IOException {
 
 		File rootDir;
 		try {
 			rootDir = rootDirResource.getFile().getAbsoluteFile();
 		}
 		catch (IOException ex) {
 			if (logger.isWarnEnabled()) {
 				logger.warn("Cannot search for matching files underneath " + rootDirResource +
 						" because it does not correspond to a directory in the file system", ex);
 			}
 			return Collections.emptySet();
 		}
 		return doFindMatchingFileSystemResources(rootDir, subPattern);
 	}
 
 	/**
 	 * Find all resources in the file system that match the given location pattern
 	 * via the Ant-style PathMatcher.
 	 * @param rootDir the root directory in the file system
 	 * @param subPattern the sub pattern to match (below the root directory)
 	 * @return a mutable Set of matching Resource instances
 	 * @throws IOException in case of I/O errors
 	 * @see #retrieveMatchingFiles
 	 * @see org.springframework.util.PathMatcher
 	 */
 	protected Set<Resource> doFindMatchingFileSystemResources(File rootDir, String subPattern) throws IOException {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Looking for matching resources in directory tree [" + rootDir.getPath() + "]");
 		}
 		Set<File> matchingFiles = retrieveMatchingFiles(rootDir, subPattern);
 		Set<Resource> result = new LinkedHashSet<Resource>(matchingFiles.size());
 		for (File file : matchingFiles) {
 			result.add(new FileSystemResource(file));
 		}
 		return result;
 	}
 
 	/**
 	 * Retrieve files that match the given path pattern,
 	 * checking the given directory and its subdirectories.
 	 * @param rootDir the directory to start from
 	 * @param pattern the pattern to match against,
 	 * relative to the root directory
 	 * @return a mutable Set of matching Resource instances
 	 * @throws IOException if directory contents could not be retrieved
 	 */
 	protected Set<File> retrieveMatchingFiles(File rootDir, String pattern) throws IOException {
 		if (!rootDir.exists()) {
 			// Silently skip non-existing directories.
 			if (logger.isDebugEnabled()) {
 				logger.debug("Skipping [" + rootDir.getAbsolutePath() + "] because it does not exist");
 			}
 			return Collections.emptySet();
 		}
 		if (!rootDir.isDirectory()) {
 			// Complain louder if it exists but is no directory.
 			if (logger.isWarnEnabled()) {
 				logger.warn("Skipping [" + rootDir.getAbsolutePath() + "] because it does not denote a directory");
 			}
 			return Collections.emptySet();
 		}
 		if (!rootDir.canRead()) {
 			if (logger.isWarnEnabled()) {
 				logger.warn("Cannot search for matching files underneath directory [" + rootDir.getAbsolutePath() +
 						"] because the application is not allowed to read the directory");
 			}
 			return Collections.emptySet();
 		}
 		String fullPattern = StringUtils.replace(rootDir.getAbsolutePath(), File.separator, "/");
 		if (!pattern.startsWith("/")) {
 			fullPattern += "/";
 		}
 		fullPattern = fullPattern + StringUtils.replace(pattern, File.separator, "/");
 		Set<File> result = new LinkedHashSet<File>(8);
 		doRetrieveMatchingFiles(fullPattern, rootDir, result);
 		return result;
 	}
 
 	/**
 	 * Recursively retrieve files that match the given pattern,
 	 * adding them to the given result list.
 	 * @param fullPattern the pattern to match against,
 	 * with prepended root directory path
 	 * @param dir the current directory
 	 * @param result the Set of matching File instances to add to
 	 * @throws IOException if directory contents could not be retrieved
 	 */
 	protected void doRetrieveMatchingFiles(String fullPattern, File dir, Set<File> result) throws IOException {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Searching directory [" + dir.getAbsolutePath() +
 					"] for files matching pattern [" + fullPattern + "]");
 		}
 		File[] dirContents = dir.listFiles();
 		if (dirContents == null) {
 			if (logger.isWarnEnabled()) {
 				logger.warn("Could not retrieve contents of directory [" + dir.getAbsolutePath() + "]");
 			}
 			return;
 		}
 		for (File content : dirContents) {
 			String currPath = StringUtils.replace(content.getAbsolutePath(), File.separator, "/");
 			if (content.isDirectory() && getPathMatcher().matchStart(fullPattern, currPath + "/")) {
 				if (!content.canRead()) {
 					if (logger.isDebugEnabled()) {
 						logger.debug("Skipping subdirectory [" + dir.getAbsolutePath() +
 								"] because the application is not allowed to read the directory");
 					}
 				}
 				else {
 					doRetrieveMatchingFiles(fullPattern, content, result);
 				}
 			}
 			if (getPathMatcher().match(fullPattern, currPath)) {
 				result.add(content);
 			}
 		}
 	}
 
 
 	/**
 	 * Inner delegate class, avoiding a hard JBoss VFS API dependency at runtime.
 	 */
 	private static class VfsResourceMatchingDelegate {
 
 		public static Set<Resource> findMatchingResources(
 				Resource rootResource, String locationPattern, PathMatcher pathMatcher) throws IOException {
 			Object root = VfsPatternUtils.findRoot(rootResource.getURL());
 			PatternVirtualFileVisitor visitor =
 					new PatternVirtualFileVisitor(VfsPatternUtils.getPath(root), locationPattern, pathMatcher);
 			VfsPatternUtils.visit(root, visitor);
 			return visitor.getResources();
 		}
 	}
 
 
 	/**
 	 * VFS visitor for path matching purposes.
 	 */
 	@SuppressWarnings("unused")
 	private static class PatternVirtualFileVisitor implements InvocationHandler {
 
 		private final String subPattern;
 
 		private final PathMatcher pathMatcher;
 
 		private final String rootPath;
 
 		private final Set<Resource> resources = new LinkedHashSet<Resource>();
 
 		public PatternVirtualFileVisitor(String rootPath, String subPattern, PathMatcher pathMatcher) {
 			this.subPattern = subPattern;
 			this.pathMatcher = pathMatcher;
 			this.rootPath = (rootPath.length() == 0 || rootPath.endsWith("/") ? rootPath : rootPath + "/");
 		}
 
 		@Override
 		public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
 			String methodName = method.getName();
 			if (Object.class.equals(method.getDeclaringClass())) {
 				if (methodName.equals("equals")) {
 					// Only consider equal when proxies are identical.
 					return (proxy == args[0]);
 				}
 				else if (methodName.equals("hashCode")) {
 					return System.identityHashCode(proxy);
 				}
 			}
 			else if ("getAttributes".equals(methodName)) {
 				return getAttributes();
 			}
 			else if ("visit".equals(methodName)) {
 				visit(args[0]);
 				return null;
 			}
 			else if ("toString".equals(methodName)) {
 				return toString();
 			}
 
 			throw new IllegalStateException("Unexpected method invocation: " + method);
 		}
 
 		public void visit(Object vfsResource) {
 			if (this.pathMatcher.match(this.subPattern,
 					VfsPatternUtils.getPath(vfsResource).substring(this.rootPath.length()))) {
 				this.resources.add(new VfsResource(vfsResource));
 			}
 		}
 
 		public Object getAttributes() {
 			return VfsPatternUtils.getVisitorAttribute();
 		}
 
 		public Set<Resource> getResources() {
 			return this.resources;
 		}
 
 		public int size() {
 			return this.resources.size();
 		}
 
 		@Override
 		public String toString() {
 			return "sub-pattern: " + this.subPattern + ", resources: " + this.resources;
 		}
 	}
 
 }