spring2.5开始的新特性：packagesToScan路径解析分析

1. <property name="packagesToScan" value="com.xxx.entity" />， 会解析成"classpath*:com/xxx/entity**/*.class"，这个路径可以找出com/xxx/entity根目录下的类文件

2. <property name="packagesToScan" value="com.xxx.entity.*" />， 会解析成"classpath*:com/xxx/entity/***/*.class"，这个路径可以找出com/xxx/entity根目录下一级子目录中的类文件，如com/xxx/entity/son/Hi.class ，而不能找出com/xxx/entity目录下的类文件。

3. <property name="packagesToScan" value="com.xxx.entity." />(注意最后的点) ， 会转换成"classpath*:com/xxx/entity/**/*.class"，这个路径可以找出com/xxx/entity根目录下及其子孙目录下所有的类文件. 一般来讲，这些就是我们要的文件。

上面是网友得出的结论，尚未有时间验证。

自己大致了解了一下.看了它的源码我们可以看到。

前缀默认为："classpath*:"

后缀默认为："/**/*.class"

PathMatchingResourcePatternResolver类中

if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {

把location去掉了前缀："classpath*:"

关键是中间的解析

ClassUtil类中：

public static String convertClassNameToResourcePath(String className) {
		Assert.notNull(className, "Class name must not be null");
		return className.replace('.', '/');
}

我们可以看到它把.解析成了/

第一种则为：

com/tudou/entity/**/*.class

第二种则为：

com/tudou/entity/*/**/*.class

第三种则为：

com/tudou/entity//**/*.class

接下来就是判断了：

package com.tudou.t2;
/**
 * 测试spring源码内packageToScan的方法
 * @author tudou
 *
 */
public class packageToScans {
	public static void main(String[] args) {
		String path1="classpath*:com/tudou/entity/**/*.class";
		String path2="classpath*:com/tudou/entity/*/**/*.class";
		String path3="classpath*:com/tudou/entity//**/*.class";
		String s1=determineRootDir(path1);
		String s2=determineRootDir(path2);
		String s3=determineRootDir(path3);
		//打印得成s1,s2,s3的值均为：classpath*:下面截取可以得到它的完整包名+类名
		
		String subPattern1 = path1.substring(s1.length());
		String subPattern2 = path1.substring(s2.length());
		String subPattern3 = path1.substring(s3.length());
		System.out.println(subPattern1);
		System.out.println(subPattern2);
		System.out.println(subPattern3);
	}
	
	protected static String determineRootDir(String location) {
		int prefixEnd = location.indexOf(":") + 1;
		int rootDirEnd = location.length();
		while (rootDirEnd > prefixEnd) {
			rootDirEnd = location.lastIndexOf('/', rootDirEnd - 2) + 1;
		}
		if (rootDirEnd == 0) {
			rootDirEnd = prefixEnd;
		}
		return location.substring(0, rootDirEnd);
	}
}

再往后：

我们可以看到它会去jar,zip,路径里面去判断不同的路径。可谓是相当全面了！当然我们只管看路径寻找我们的类即可即可。

取绝对路径。

spring源码如下：

private static final String RESOURCE_PATTERN = "/**/*.class";
其中：String CLASSPATH_ALL_URL_PREFIX = "classpath*:";


protected void scanPackages(AnnotationConfiguration config) {if (this.packagesToScan != null) {try {for (String pkg : this.packagesToScan) {String pattern = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +ClassUtils.convertClassNameToResourcePath(pkg) + RESOURCE_PATTERN;Resource[]
 resources = this.resourcePatternResolver.getResources(pattern);MetadataReaderFactory readerFactory = new CachingMetadataReaderFactory(this.resourcePatternResolver);for (Resource resource : resources) {if (resource.isReadable()) {MetadataReader reader = readerFactory.getMetadataReader(resource);String
 className = reader.getClassMetadata().getClassName();if (matchesFilter(reader, readerFactory)) {config.addAnnotatedClass(this.resourcePatternResolver.getClassLoader().loadClass(className));}}}}}catch (IOException ex) {throw new MappingException("Failed to
 scan classpath for unlisted classes", ex);}catch (ClassNotFoundException ex) {throw new MappingException("Failed to load annotated classes from classpath", ex);}}}



public static String convertClassNameToResourcePath(String className) {
		Assert.notNull(className, "Class name must not be null");
		return className.replace('.', '/');
	}

ResourcePatternResolver类中主要代码：
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.URISyntaxException;
import java.net.URL;
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.PathMatcher;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ResourceUtils;
import org.springframework.util.StringUtils;


public class PathMatchingResourcePatternResolver implements ResourcePatternResolver {

	private static final Log logger = LogFactory.getLog(PathMatchingResourcePatternResolver.class);

	private static Method equinoxResolveMethod;

	static {
		// Detect Equinox OSGi (e.g. on WebSphere 6.1)
		try {
			Class<?> fileLocatorClass = PathMatchingResourcePatternResolver.class.getClassLoader().loadClass(
					"org.eclipse.core.runtime.FileLocator");
			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 with a DefaultResourceLoader.
	 * @param classLoader the ClassLoader to load classpath resources with,
	 * or <code>null</code> 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);
	}

	/**
	 * 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;
	}

	/**
	 * Return the ResourceLoader that this pattern resolver works with.
	 */
	public ResourceLoader getResourceLoader() {
		return this.resourceLoader;
	}

	/**
	 * Return the ClassLoader that this pattern resolver works with
	 * (never <code>null</code>).
	 */
	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;
	}


	public Resource getResource(String location) {
		return getResourceLoader().getResource(location);
	}

	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.
	 * @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);
		}
		Enumeration<URL> resourceUrls = getClassLoader().getResources(path);
		Set<Resource> result = new LinkedHashSet<Resource>(16);
		while (resourceUrls.hasMoreElements()) {
			URL url = resourceUrls.nextElement();
			result.add(convertClassLoaderURL(url));
		}
		return result.toArray(new Resource[result.size()]);
	}

	/**
	 * Convert the given URL as returned from the ClassLoader into a Resource object.
	 * <p>The default implementation simply creates a 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);
	}

	/**
	 * 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 (isJarResource(rootDirResource)) {
				result.addAll(doFindPathMatchingJarResources(rootDirResource, subPattern));
			}
			else if (rootDirResource.getURL().getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
				result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirResource, subPattern, getPathMatcher()));
			}
			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</code>
	 * and passing it into <code>retrieveMatchingFiles</code>, 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</code> 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 the 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;
			jarCon.setUseCaches(false);
			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 the 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 the 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 the Set of matching File 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.
	 */
	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 + "/");
		}

		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;
		}

		@SuppressWarnings("unused")
		public int size() {
			return this.resources.size();
		}

		public String toString() {
			StringBuilder sb = new StringBuilder();
			sb.append("sub-pattern: ").append(this.subPattern);
			sb.append(", resources: ").append(this.resources);
			return sb.toString();
		}
	}

}





CachingMetadataReaderFactory类核心代码：

package org.springframework.core.type.classreading;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.Map;

import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;

/**
 * Caching implementation of the {@link MetadataReaderFactory} interface,
 * caching {@link MetadataReader} per Spring {@link Resource} handle
 * (i.e. per ".class" file).
 *
 * @author Juergen Hoeller
 * @author Costin Leau
 * @since 2.5
 */
public class CachingMetadataReaderFactory extends SimpleMetadataReaderFactory {

	/** Default maximum number of entries for the MetadataReader cache: 256 */
	public static final int DEFAULT_CACHE_LIMIT = 256;


	private volatile int cacheLimit = DEFAULT_CACHE_LIMIT;

	private final Map<Resource, MetadataReader> classReaderCache =
			new LinkedHashMap<Resource, MetadataReader>(DEFAULT_CACHE_LIMIT, 0.75f, true) {
				@Override
				protected boolean removeEldestEntry(Map.Entry<Resource, MetadataReader> eldest) {
					return size() > getCacheLimit();
				}
			};


	/**
	 * Create a new CachingMetadataReaderFactory for the default class loader.
	 */
	public CachingMetadataReaderFactory() {
		super();
	}

	/**
	 * Create a new CachingMetadataReaderFactory for the given resource loader.
	 * @param resourceLoader the Spring ResourceLoader to use
	 * (also determines the ClassLoader to use)
	 */
	public CachingMetadataReaderFactory(ResourceLoader resourceLoader) {
		super(resourceLoader);
	}

	/**
	 * Create a new CachingMetadataReaderFactory for the given class loader.
	 * @param classLoader the ClassLoader to use
	 */
	public CachingMetadataReaderFactory(ClassLoader classLoader) {
		super(classLoader);
	}


	/**
	 * Specify the maximum number of entries for the MetadataReader cache.
	 * Default is 256.
	 */
	public void setCacheLimit(int cacheLimit) {
		this.cacheLimit = cacheLimit;
	}

	/**
	 * Return the maximum number of entries for the MetadataReader cache.
	 */
	public int getCacheLimit() {
		return this.cacheLimit;
	}


	@Override
	public MetadataReader getMetadataReader(Resource resource) throws IOException {
		if (getCacheLimit() <= 0) {
			return super.getMetadataReader(resource);
		}
		synchronized (this.classReaderCache) {
			MetadataReader metadataReader = this.classReaderCache.get(resource);
			if (metadataReader == null) {
				metadataReader = super.getMetadataReader(resource);
				this.classReaderCache.put(resource, metadataReader);
			}
			return metadataReader;
		}
	}

}