guava/src/com/google/common/reflect/ClassPath.java - platform/external/guava - Git at Google

 /*
  * Copyright (C) 2012 The Guava 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 com.google.common.reflect;

 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.StandardSystemProperty.JAVA_CLASS_PATH;
 import static com.google.common.base.StandardSystemProperty.PATH_SEPARATOR;
 import static java.util.logging.Level.WARNING;

 import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.CharMatcher;
 import com.google.common.base.Predicate;
 import com.google.common.base.Splitter;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Maps;
 import com.google.common.collect.MultimapBuilder;
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 import com.google.common.io.ByteSource;
 import com.google.common.io.CharSource;
 import com.google.common.io.Resources;
 import java.io.File;
 import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.nio.charset.Charset;
 import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.jar.Attributes;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
 import java.util.logging.Logger;
 import org.checkerframework.checker.nullness.qual.Nullable;

 /**
  * Scans the source of a {@link ClassLoader} and finds all loadable classes and resources.
  *
  * <p><b>Warning:</b> Current limitations:
  *
  * <ul>
  *   <li>Looks only for files and JARs in URLs available from {@link URLClassLoader} instances or
  *       the {@linkplain ClassLoader#getSystemClassLoader() system class loader}.
  *   <li>Only understands {@code file:} URLs.
  * </ul>
  *
  * <p>In the case of directory classloaders, symlinks are supported but cycles are not traversed.
  * This guarantees discovery of each <em>unique</em> loadable resource. However, not all possible
  * aliases for resources on cyclic paths will be listed.
  *
  * @author Ben Yu
  * @since 14.0
  */
 @Beta
 public final class ClassPath {
   private static final Logger logger = Logger.getLogger(ClassPath.class.getName());

   private static final Predicate<ClassInfo> IS_TOP_LEVEL =
       new Predicate<ClassInfo>() {
         @Override
         public boolean apply(ClassInfo info) {
           return info.className.indexOf('$') == -1;
         }
       };

   /** Separator for the Class-Path manifest attribute value in jar files. */
   private static final Splitter CLASS_PATH_ATTRIBUTE_SEPARATOR =
       Splitter.on(" ").omitEmptyStrings();

   private static final String CLASS_FILE_NAME_EXTENSION = ".class";

   private final ImmutableSet<ResourceInfo> resources;

   private ClassPath(ImmutableSet<ResourceInfo> resources) {
     this.resources = resources;
   }

   /**
    * Returns a {@code ClassPath} representing all classes and resources loadable from {@code
    * classloader} and its ancestor class loaders.
    *
    * <p><b>Warning:</b> {@code ClassPath} can find classes and resources only from:
    *
    * <ul>
    *   <li>{@link URLClassLoader} instances' {@code file:} URLs
    *   <li>the {@linkplain ClassLoader#getSystemClassLoader() system class loader}. To search the
    *       system class loader even when it is not a {@link URLClassLoader} (as in Java 9), {@code
    *       ClassPath} searches the files from the {@code java.class.path} system property.
    * </ul>
    *
    * @throws IOException if the attempt to read class path resources (jar files or directories)
    *     failed.
    */
   public static ClassPath from(ClassLoader classloader) throws IOException {
     DefaultScanner scanner = new DefaultScanner();
     scanner.scan(classloader);
     return new ClassPath(scanner.getResources());
   }

   /**
    * Returns all resources loadable from the current class path, including the class files of all
    * loadable classes but excluding the "META-INF/MANIFEST.MF" file.
    */
   public ImmutableSet<ResourceInfo> getResources() {
     return resources;
   }

   /**
    * Returns all classes loadable from the current class path.
    *
    * @since 16.0
    */
   public ImmutableSet<ClassInfo> getAllClasses() {
     return FluentIterable.from(resources).filter(ClassInfo.class).toSet();
   }

   /** Returns all top level classes loadable from the current class path. */
   public ImmutableSet<ClassInfo> getTopLevelClasses() {
     return FluentIterable.from(resources).filter(ClassInfo.class).filter(IS_TOP_LEVEL).toSet();
   }

   /** Returns all top level classes whose package name is {@code packageName}. */
   public ImmutableSet<ClassInfo> getTopLevelClasses(String packageName) {
     checkNotNull(packageName);
     ImmutableSet.Builder<ClassInfo> builder = ImmutableSet.builder();
     for (ClassInfo classInfo : getTopLevelClasses()) {
       if (classInfo.getPackageName().equals(packageName)) {
         builder.add(classInfo);
       }
     }
     return builder.build();
   }

   /**
    * Returns all top level classes whose package name is {@code packageName} or starts with {@code
    * packageName} followed by a '.'.
    */
   public ImmutableSet<ClassInfo> getTopLevelClassesRecursive(String packageName) {
     checkNotNull(packageName);
     String packagePrefix = packageName + '.';
     ImmutableSet.Builder<ClassInfo> builder = ImmutableSet.builder();
     for (ClassInfo classInfo : getTopLevelClasses()) {
       if (classInfo.getName().startsWith(packagePrefix)) {
         builder.add(classInfo);
       }
     }
     return builder.build();
   }

   /**
    * Represents a class path resource that can be either a class file or any other resource file
    * loadable from the class path.
    *
    * @since 14.0
    */
   @Beta
   public static class ResourceInfo {
     private final String resourceName;

     final ClassLoader loader;

     static ResourceInfo of(String resourceName, ClassLoader loader) {
       if (resourceName.endsWith(CLASS_FILE_NAME_EXTENSION)) {
         return new ClassInfo(resourceName, loader);
       } else {
         return new ResourceInfo(resourceName, loader);
       }
     }

     ResourceInfo(String resourceName, ClassLoader loader) {
       this.resourceName = checkNotNull(resourceName);
       this.loader = checkNotNull(loader);
     }

     /**
      * Returns the url identifying the resource.
      *
      * <p>See {@link ClassLoader#getResource}
      *
      * @throws NoSuchElementException if the resource cannot be loaded through the class loader,
      *     despite physically existing in the class path.
      */
     public final URL url() {
       URL url = loader.getResource(resourceName);
       if (url == null) {
         throw new NoSuchElementException(resourceName);
       }
       return url;
     }

     /**
      * Returns a {@link ByteSource} view of the resource from which its bytes can be read.
      *
      * @throws NoSuchElementException if the resource cannot be loaded through the class loader,
      *     despite physically existing in the class path.
      * @since 20.0
      */
     public final ByteSource asByteSource() {
       return Resources.asByteSource(url());
     }

     /**
      * Returns a {@link CharSource} view of the resource from which its bytes can be read as
      * characters decoded with the given {@code charset}.
      *
      * @throws NoSuchElementException if the resource cannot be loaded through the class loader,
      *     despite physically existing in the class path.
      * @since 20.0
      */
     public final CharSource asCharSource(Charset charset) {
       return Resources.asCharSource(url(), charset);
     }

     /** Returns the fully qualified name of the resource. Such as "com/mycomp/foo/bar.txt". */
     public final String getResourceName() {
       return resourceName;
     }

     @Override
     public int hashCode() {
       return resourceName.hashCode();
     }

     @Override
     public boolean equals(Object obj) {
       if (obj instanceof ResourceInfo) {
         ResourceInfo that = (ResourceInfo) obj;
         return resourceName.equals(that.resourceName) && loader == that.loader;
       }
       return false;
     }

     // Do not change this arbitrarily. We rely on it for sorting ResourceInfo.
     @Override
     public String toString() {
       return resourceName;
     }
   }

   /**
    * Represents a class that can be loaded through {@link #load}.
    *
    * @since 14.0
    */
   @Beta
   public static final class ClassInfo extends ResourceInfo {
     private final String className;

     ClassInfo(String resourceName, ClassLoader loader) {
       super(resourceName, loader);
       this.className = getClassName(resourceName);
     }

     /**
      * Returns the package name of the class, without attempting to load the class.
      *
      * <p>Behaves identically to {@link Package#getName()} but does not require the class (or
      * package) to be loaded.
      */
     public String getPackageName() {
       return Reflection.getPackageName(className);
     }

     /**
      * Returns the simple name of the underlying class as given in the source code.
      *
      * <p>Behaves identically to {@link Class#getSimpleName()} but does not require the class to be
      * loaded.
      */
     public String getSimpleName() {
       int lastDollarSign = className.lastIndexOf('$');
       if (lastDollarSign != -1) {
         String innerClassName = className.substring(lastDollarSign + 1);
         // local and anonymous classes are prefixed with number (1,2,3...), anonymous classes are
         // entirely numeric whereas local classes have the user supplied name as a suffix
         return CharMatcher.digit().trimLeadingFrom(innerClassName);
       }
       String packageName = getPackageName();
       if (packageName.isEmpty()) {
         return className;
       }

       // Since this is a top level class, its simple name is always the part after package name.
       return className.substring(packageName.length() + 1);
     }

     /**
      * Returns the fully qualified name of the class.
      *
      * <p>Behaves identically to {@link Class#getName()} but does not require the class to be
      * loaded.
      */
     public String getName() {
       return className;
     }

     /**
      * Loads (but doesn't link or initialize) the class.
      *
      * @throws LinkageError when there were errors in loading classes that this class depends on.
      *     For example, {@link NoClassDefFoundError}.
      */
     public Class<?> load() {
       try {
         return loader.loadClass(className);
       } catch (ClassNotFoundException e) {
         // Shouldn't happen, since the class name is read from the class path.
         throw new IllegalStateException(e);
       }
     }

     @Override
     public String toString() {
       return className;
     }
   }

   /**
    * Abstract class that scans through the class path represented by a {@link ClassLoader} and calls
    * {@link #scanDirectory} and {@link #scanJarFile} for directories and jar files on the class path
    * respectively.
    */
   abstract static class Scanner {

     // We only scan each file once independent of the classloader that resource might be associated
     // with.
     private final Set<File> scannedUris = Sets.newHashSet();

     public final void scan(ClassLoader classloader) throws IOException {
       for (Entry<File, ClassLoader> entry : getClassPathEntries(classloader).entrySet()) {
         scan(entry.getKey(), entry.getValue());
       }
     }

     @VisibleForTesting
     final void scan(File file, ClassLoader classloader) throws IOException {
       if (scannedUris.add(file.getCanonicalFile())) {
         scanFrom(file, classloader);
       }
     }

     /** Called when a directory is scanned for resource files. */
     protected abstract void scanDirectory(ClassLoader loader, File directory) throws IOException;

     /** Called when a jar file is scanned for resource entries. */
     protected abstract void scanJarFile(ClassLoader loader, JarFile file) throws IOException;

     private void scanFrom(File file, ClassLoader classloader) throws IOException {
       try {
         if (!file.exists()) {
           return;
         }
       } catch (SecurityException e) {
         logger.warning("Cannot access " + file + ": " + e);
         // TODO(emcmanus): consider whether to log other failure cases too.
         return;
       }
       if (file.isDirectory()) {
         scanDirectory(classloader, file);
       } else {
         scanJar(file, classloader);
       }
     }

     private void scanJar(File file, ClassLoader classloader) throws IOException {
       JarFile jarFile;
       try {
         jarFile = new JarFile(file);
       } catch (IOException e) {
         // Not a jar file
         return;
       }
       try {
         for (File path : getClassPathFromManifest(file, jarFile.getManifest())) {
           scan(path, classloader);
         }
         scanJarFile(classloader, jarFile);
       } finally {
         try {
           jarFile.close();
         } catch (IOException ignored) {
         }
       }
     }

     /**
      * Returns the class path URIs specified by the {@code Class-Path} manifest attribute, according
      * to <a
      * href="http://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#Main_Attributes">JAR
      * File Specification</a>. If {@code manifest} is null, it means the jar file has no manifest,
      * and an empty set will be returned.
      */
     @VisibleForTesting
     static ImmutableSet<File> getClassPathFromManifest(File jarFile, @Nullable Manifest manifest) {
       if (manifest == null) {
         return ImmutableSet.of();
       }
       ImmutableSet.Builder<File> builder = ImmutableSet.builder();
       String classpathAttribute =
           manifest.getMainAttributes().getValue(Attributes.Name.CLASS_PATH.toString());
       if (classpathAttribute != null) {
         for (String path : CLASS_PATH_ATTRIBUTE_SEPARATOR.split(classpathAttribute)) {
           URL url;
           try {
             url = getClassPathEntry(jarFile, path);
           } catch (MalformedURLException e) {
             // Ignore bad entry
             logger.warning("Invalid Class-Path entry: " + path);
             continue;
           }
           if (url.getProtocol().equals("file")) {
             builder.add(toFile(url));
           }
         }
       }
       return builder.build();
     }

     @VisibleForTesting
     static ImmutableMap<File, ClassLoader> getClassPathEntries(ClassLoader classloader) {
       LinkedHashMap<File, ClassLoader> entries = Maps.newLinkedHashMap();
       // Search parent first, since it's the order ClassLoader#loadClass() uses.
       ClassLoader parent = classloader.getParent();
       if (parent != null) {
         entries.putAll(getClassPathEntries(parent));
       }
       for (URL url : getClassLoaderUrls(classloader)) {
         if (url.getProtocol().equals("file")) {
           File file = toFile(url);
           if (!entries.containsKey(file)) {
             entries.put(file, classloader);
           }
         }
       }
       return ImmutableMap.copyOf(entries);
     }

     private static ImmutableList<URL> getClassLoaderUrls(ClassLoader classloader) {
       if (classloader instanceof URLClassLoader) {
         return ImmutableList.copyOf(((URLClassLoader) classloader).getURLs());
       }
       if (classloader.equals(ClassLoader.getSystemClassLoader())) {
         return parseJavaClassPath();
       }
       return ImmutableList.of();
     }

     /**
      * Returns the URLs in the class path specified by the {@code java.class.path} {@linkplain
      * System#getProperty system property}.
      */
     @VisibleForTesting // TODO(b/65488446): Make this a public API.
     static ImmutableList<URL> parseJavaClassPath() {
       ImmutableList.Builder<URL> urls = ImmutableList.builder();
       for (String entry : Splitter.on(PATH_SEPARATOR.value()).split(JAVA_CLASS_PATH.value())) {
         try {
           try {
             urls.add(new File(entry).toURI().toURL());
           } catch (SecurityException e) { // File.toURI checks to see if the file is a directory
             urls.add(new URL("file", null, new File(entry).getAbsolutePath()));
           }
         } catch (MalformedURLException e) {
           logger.log(WARNING, "malformed classpath entry: " + entry, e);
         }
       }
       return urls.build();
     }

     /**
      * Returns the absolute uri of the Class-Path entry value as specified in <a
      * href="http://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#Main_Attributes">JAR
      * File Specification</a>. Even though the specification only talks about relative urls,
      * absolute urls are actually supported too (for example, in Maven surefire plugin).
      */
     @VisibleForTesting
     static URL getClassPathEntry(File jarFile, String path) throws MalformedURLException {
       return new URL(jarFile.toURI().toURL(), path);
     }
   }

   @VisibleForTesting
   static final class DefaultScanner extends Scanner {
     private final SetMultimap<ClassLoader, String> resources =
         MultimapBuilder.hashKeys().linkedHashSetValues().build();

     ImmutableSet<ResourceInfo> getResources() {
       ImmutableSet.Builder<ResourceInfo> builder = ImmutableSet.builder();
       for (Entry<ClassLoader, String> entry : resources.entries()) {
         builder.add(ResourceInfo.of(entry.getValue(), entry.getKey()));
       }
       return builder.build();
     }

     @Override
     protected void scanJarFile(ClassLoader classloader, JarFile file) {
       Enumeration<JarEntry> entries = file.entries();
       while (entries.hasMoreElements()) {
         JarEntry entry = entries.nextElement();
         if (entry.isDirectory() || entry.getName().equals(JarFile.MANIFEST_NAME)) {
           continue;
         }
         resources.get(classloader).add(entry.getName());
       }
     }

     @Override
     protected void scanDirectory(ClassLoader classloader, File directory) throws IOException {
       Set<File> currentPath = new HashSet<>();
       currentPath.add(directory.getCanonicalFile());
       scanDirectory(directory, classloader, "", currentPath);
     }

     /**
      * Recursively scan the given directory, adding resources for each file encountered. Symlinks
      * which have already been traversed in the current tree path will be skipped to eliminate
      * cycles; otherwise symlinks are traversed.
      *
      * @param directory the root of the directory to scan
      * @param classloader the classloader that includes resources found in {@code directory}
      * @param packagePrefix resource path prefix inside {@code classloader} for any files found
      *     under {@code directory}
      * @param currentPath canonical files already visited in the current directory tree path, for
      *     cycle elimination
      */
     private void scanDirectory(
         File directory, ClassLoader classloader, String packagePrefix, Set<File> currentPath)
         throws IOException {
       File[] files = directory.listFiles();
       if (files == null) {
         logger.warning("Cannot read directory " + directory);
         // IO error, just skip the directory
         return;
       }
       for (File f : files) {
         String name = f.getName();
         if (f.isDirectory()) {
           File deref = f.getCanonicalFile();
           if (currentPath.add(deref)) {
             scanDirectory(deref, classloader, packagePrefix + name + "/", currentPath);
             currentPath.remove(deref);
           }
         } else {
           String resourceName = packagePrefix + name;
           if (!resourceName.equals(JarFile.MANIFEST_NAME)) {
             resources.get(classloader).add(resourceName);
           }
         }
       }
     }
   }

   @VisibleForTesting
   static String getClassName(String filename) {
     int classNameEnd = filename.length() - CLASS_FILE_NAME_EXTENSION.length();
     return filename.substring(0, classNameEnd).replace('/', '.');
   }

   // TODO(benyu): Try java.nio.file.Paths#get() when Guava drops JDK 6 support.
   @VisibleForTesting
   static File toFile(URL url) {
     checkArgument(url.getProtocol().equals("file"));
     try {
       return new File(url.toURI()); // Accepts escaped characters like %20.
     } catch (URISyntaxException e) { // URL.toURI() doesn't escape chars.
       return new File(url.getPath()); // Accepts non-escaped chars like space.
     }
   }
 }
	/*
	* Copyright (C) 2012 The Guava 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 com.google.common.reflect;

	import static com.google.common.base.Preconditions.checkArgument;
	import static com.google.common.base.Preconditions.checkNotNull;
	import static com.google.common.base.StandardSystemProperty.JAVA_CLASS_PATH;
	import static com.google.common.base.StandardSystemProperty.PATH_SEPARATOR;
	import static java.util.logging.Level.WARNING;

	import com.google.common.annotations.Beta;
	import com.google.common.annotations.VisibleForTesting;
	import com.google.common.base.CharMatcher;
	import com.google.common.base.Predicate;
	import com.google.common.base.Splitter;
	import com.google.common.collect.FluentIterable;
	import com.google.common.collect.ImmutableList;
	import com.google.common.collect.ImmutableMap;
	import com.google.common.collect.ImmutableSet;
	import com.google.common.collect.Maps;
	import com.google.common.collect.MultimapBuilder;
	import com.google.common.collect.SetMultimap;
	import com.google.common.collect.Sets;
	import com.google.common.io.ByteSource;
	import com.google.common.io.CharSource;
	import com.google.common.io.Resources;
	import java.io.File;
	import java.io.IOException;
	import java.net.MalformedURLException;
	import java.net.URISyntaxException;
	import java.net.URL;
	import java.net.URLClassLoader;
	import java.nio.charset.Charset;
	import java.util.Enumeration;
	import java.util.HashSet;
	import java.util.LinkedHashMap;
	import java.util.Map.Entry;
	import java.util.NoSuchElementException;
	import java.util.Set;
	import java.util.jar.Attributes;
	import java.util.jar.JarEntry;
	import java.util.jar.JarFile;
	import java.util.jar.Manifest;
	import java.util.logging.Logger;
	import org.checkerframework.checker.nullness.qual.Nullable;

	/**
	* Scans the source of a {@link ClassLoader} and finds all loadable classes and resources.
	*
	* <p><b>Warning:</b> Current limitations:
	*
	* <ul>
	* <li>Looks only for files and JARs in URLs available from {@link URLClassLoader} instances or
	* the {@linkplain ClassLoader#getSystemClassLoader() system class loader}.
	* <li>Only understands {@code file:} URLs.
	* </ul>
	*
	* <p>In the case of directory classloaders, symlinks are supported but cycles are not traversed.
	* This guarantees discovery of each <em>unique</em> loadable resource. However, not all possible
	* aliases for resources on cyclic paths will be listed.
	*
	* @author Ben Yu
	* @since 14.0
	*/
	@Beta
	public final class ClassPath {
	private static final Logger logger = Logger.getLogger(ClassPath.class.getName());

	private static final Predicate<ClassInfo> IS_TOP_LEVEL =
	new Predicate<ClassInfo>() {
	@Override
	public boolean apply(ClassInfo info) {
	return info.className.indexOf('$') == -1;
	}
	};

	/** Separator for the Class-Path manifest attribute value in jar files. */
	private static final Splitter CLASS_PATH_ATTRIBUTE_SEPARATOR =
	Splitter.on(" ").omitEmptyStrings();

	private static final String CLASS_FILE_NAME_EXTENSION = ".class";

	private final ImmutableSet<ResourceInfo> resources;

	private ClassPath(ImmutableSet<ResourceInfo> resources) {
	this.resources = resources;
	}

	/**
	* Returns a {@code ClassPath} representing all classes and resources loadable from {@code
	* classloader} and its ancestor class loaders.
	*
	* <p><b>Warning:</b> {@code ClassPath} can find classes and resources only from:
	*
	* <ul>
	* <li>{@link URLClassLoader} instances' {@code file:} URLs
	* <li>the {@linkplain ClassLoader#getSystemClassLoader() system class loader}. To search the
	* system class loader even when it is not a {@link URLClassLoader} (as in Java 9), {@code
	* ClassPath} searches the files from the {@code java.class.path} system property.
	* </ul>
	*
	* @throws IOException if the attempt to read class path resources (jar files or directories)
	* failed.
	*/
	public static ClassPath from(ClassLoader classloader) throws IOException {
	DefaultScanner scanner = new DefaultScanner();
	scanner.scan(classloader);
	return new ClassPath(scanner.getResources());
	}

	/**
	* Returns all resources loadable from the current class path, including the class files of all
	* loadable classes but excluding the "META-INF/MANIFEST.MF" file.
	*/
	public ImmutableSet<ResourceInfo> getResources() {
	return resources;
	}

	/**
	* Returns all classes loadable from the current class path.
	*
	* @since 16.0
	*/
	public ImmutableSet<ClassInfo> getAllClasses() {
	return FluentIterable.from(resources).filter(ClassInfo.class).toSet();
	}

	/** Returns all top level classes loadable from the current class path. */
	public ImmutableSet<ClassInfo> getTopLevelClasses() {
	return FluentIterable.from(resources).filter(ClassInfo.class).filter(IS_TOP_LEVEL).toSet();
	}

	/** Returns all top level classes whose package name is {@code packageName}. */
	public ImmutableSet<ClassInfo> getTopLevelClasses(String packageName) {
	checkNotNull(packageName);
	ImmutableSet.Builder<ClassInfo> builder = ImmutableSet.builder();
	for (ClassInfo classInfo : getTopLevelClasses()) {
	if (classInfo.getPackageName().equals(packageName)) {
	builder.add(classInfo);
	}
	}
	return builder.build();
	}

	/**
	* Returns all top level classes whose package name is {@code packageName} or starts with {@code
	* packageName} followed by a '.'.
	*/
	public ImmutableSet<ClassInfo> getTopLevelClassesRecursive(String packageName) {
	checkNotNull(packageName);
	String packagePrefix = packageName + '.';
	ImmutableSet.Builder<ClassInfo> builder = ImmutableSet.builder();
	for (ClassInfo classInfo : getTopLevelClasses()) {
	if (classInfo.getName().startsWith(packagePrefix)) {
	builder.add(classInfo);
	}
	}
	return builder.build();
	}

	/**
	* Represents a class path resource that can be either a class file or any other resource file
	* loadable from the class path.
	*
	* @since 14.0
	*/
	@Beta
	public static class ResourceInfo {
	private final String resourceName;

	final ClassLoader loader;

	static ResourceInfo of(String resourceName, ClassLoader loader) {
	if (resourceName.endsWith(CLASS_FILE_NAME_EXTENSION)) {
	return new ClassInfo(resourceName, loader);
	} else {
	return new ResourceInfo(resourceName, loader);
	}
	}

	ResourceInfo(String resourceName, ClassLoader loader) {
	this.resourceName = checkNotNull(resourceName);
	this.loader = checkNotNull(loader);
	}

	/**
	* Returns the url identifying the resource.
	*
	* <p>See {@link ClassLoader#getResource}
	*
	* @throws NoSuchElementException if the resource cannot be loaded through the class loader,
	* despite physically existing in the class path.
	*/
	public final URL url() {
	URL url = loader.getResource(resourceName);
	if (url == null) {
	throw new NoSuchElementException(resourceName);
	}
	return url;
	}

	/**
	* Returns a {@link ByteSource} view of the resource from which its bytes can be read.
	*
	* @throws NoSuchElementException if the resource cannot be loaded through the class loader,
	* despite physically existing in the class path.
	* @since 20.0
	*/
	public final ByteSource asByteSource() {
	return Resources.asByteSource(url());
	}

	/**
	* Returns a {@link CharSource} view of the resource from which its bytes can be read as
	* characters decoded with the given {@code charset}.
	*
	* @throws NoSuchElementException if the resource cannot be loaded through the class loader,
	* despite physically existing in the class path.
	* @since 20.0
	*/
	public final CharSource asCharSource(Charset charset) {
	return Resources.asCharSource(url(), charset);
	}

	/** Returns the fully qualified name of the resource. Such as "com/mycomp/foo/bar.txt". */
	public final String getResourceName() {
	return resourceName;
	}

	@Override
	public int hashCode() {
	return resourceName.hashCode();
	}

	@Override
	public boolean equals(Object obj) {
	if (obj instanceof ResourceInfo) {
	ResourceInfo that = (ResourceInfo) obj;
	return resourceName.equals(that.resourceName) && loader == that.loader;
	}
	return false;
	}

	// Do not change this arbitrarily. We rely on it for sorting ResourceInfo.
	@Override
	public String toString() {
	return resourceName;
	}
	}

	/**
	* Represents a class that can be loaded through {@link #load}.
	*
	* @since 14.0
	*/
	@Beta
	public static final class ClassInfo extends ResourceInfo {
	private final String className;

	ClassInfo(String resourceName, ClassLoader loader) {
	super(resourceName, loader);
	this.className = getClassName(resourceName);
	}

	/**
	* Returns the package name of the class, without attempting to load the class.
	*
	* <p>Behaves identically to {@link Package#getName()} but does not require the class (or
	* package) to be loaded.
	*/
	public String getPackageName() {
	return Reflection.getPackageName(className);
	}

	/**
	* Returns the simple name of the underlying class as given in the source code.
	*
	* <p>Behaves identically to {@link Class#getSimpleName()} but does not require the class to be
	* loaded.
	*/
	public String getSimpleName() {
	int lastDollarSign = className.lastIndexOf('$');
	if (lastDollarSign != -1) {
	String innerClassName = className.substring(lastDollarSign + 1);
	// local and anonymous classes are prefixed with number (1,2,3...), anonymous classes are
	// entirely numeric whereas local classes have the user supplied name as a suffix
	return CharMatcher.digit().trimLeadingFrom(innerClassName);
	}
	String packageName = getPackageName();
	if (packageName.isEmpty()) {
	return className;
	}

	// Since this is a top level class, its simple name is always the part after package name.
	return className.substring(packageName.length() + 1);
	}

	/**
	* Returns the fully qualified name of the class.
	*
	* <p>Behaves identically to {@link Class#getName()} but does not require the class to be
	* loaded.
	*/
	public String getName() {
	return className;
	}

	/**
	* Loads (but doesn't link or initialize) the class.
	*
	* @throws LinkageError when there were errors in loading classes that this class depends on.
	* For example, {@link NoClassDefFoundError}.
	*/
	public Class<?> load() {
	try {
	return loader.loadClass(className);
	} catch (ClassNotFoundException e) {
	// Shouldn't happen, since the class name is read from the class path.
	throw new IllegalStateException(e);
	}
	}

	@Override
	public String toString() {
	return className;
	}
	}

	/**
	* Abstract class that scans through the class path represented by a {@link ClassLoader} and calls
	* {@link #scanDirectory} and {@link #scanJarFile} for directories and jar files on the class path
	* respectively.
	*/
	abstract static class Scanner {

	// We only scan each file once independent of the classloader that resource might be associated
	// with.
	private final Set<File> scannedUris = Sets.newHashSet();

	public final void scan(ClassLoader classloader) throws IOException {
	for (Entry<File, ClassLoader> entry : getClassPathEntries(classloader).entrySet()) {
	scan(entry.getKey(), entry.getValue());
	}
	}

	@VisibleForTesting
	final void scan(File file, ClassLoader classloader) throws IOException {
	if (scannedUris.add(file.getCanonicalFile())) {
	scanFrom(file, classloader);
	}
	}

	/** Called when a directory is scanned for resource files. */
	protected abstract void scanDirectory(ClassLoader loader, File directory) throws IOException;

	/** Called when a jar file is scanned for resource entries. */
	protected abstract void scanJarFile(ClassLoader loader, JarFile file) throws IOException;

	private void scanFrom(File file, ClassLoader classloader) throws IOException {
	try {
	if (!file.exists()) {
	return;
	}
	} catch (SecurityException e) {
	logger.warning("Cannot access " + file + ": " + e);
	// TODO(emcmanus): consider whether to log other failure cases too.
	return;
	}
	if (file.isDirectory()) {
	scanDirectory(classloader, file);
	} else {
	scanJar(file, classloader);
	}
	}

	private void scanJar(File file, ClassLoader classloader) throws IOException {
	JarFile jarFile;
	try {
	jarFile = new JarFile(file);
	} catch (IOException e) {
	// Not a jar file
	return;
	}
	try {
	for (File path : getClassPathFromManifest(file, jarFile.getManifest())) {
	scan(path, classloader);
	}
	scanJarFile(classloader, jarFile);
	} finally {
	try {
	jarFile.close();
	} catch (IOException ignored) {
	}
	}
	}

	/**
	* Returns the class path URIs specified by the {@code Class-Path} manifest attribute, according
	* to <a
	* href="http://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#Main_Attributes">JAR
	* File Specification</a>. If {@code manifest} is null, it means the jar file has no manifest,
	* and an empty set will be returned.
	*/
	@VisibleForTesting
	static ImmutableSet<File> getClassPathFromManifest(File jarFile, @Nullable Manifest manifest) {
	if (manifest == null) {
	return ImmutableSet.of();
	}
	ImmutableSet.Builder<File> builder = ImmutableSet.builder();
	String classpathAttribute =
	manifest.getMainAttributes().getValue(Attributes.Name.CLASS_PATH.toString());
	if (classpathAttribute != null) {
	for (String path : CLASS_PATH_ATTRIBUTE_SEPARATOR.split(classpathAttribute)) {
	URL url;
	try {
	url = getClassPathEntry(jarFile, path);
	} catch (MalformedURLException e) {
	// Ignore bad entry
	logger.warning("Invalid Class-Path entry: " + path);
	continue;
	}
	if (url.getProtocol().equals("file")) {
	builder.add(toFile(url));
	}
	}
	}
	return builder.build();
	}

	@VisibleForTesting
	static ImmutableMap<File, ClassLoader> getClassPathEntries(ClassLoader classloader) {
	LinkedHashMap<File, ClassLoader> entries = Maps.newLinkedHashMap();
	// Search parent first, since it's the order ClassLoader#loadClass() uses.
	ClassLoader parent = classloader.getParent();
	if (parent != null) {
	entries.putAll(getClassPathEntries(parent));
	}
	for (URL url : getClassLoaderUrls(classloader)) {
	if (url.getProtocol().equals("file")) {
	File file = toFile(url);
	if (!entries.containsKey(file)) {
	entries.put(file, classloader);
	}
	}
	}
	return ImmutableMap.copyOf(entries);
	}

	private static ImmutableList<URL> getClassLoaderUrls(ClassLoader classloader) {
	if (classloader instanceof URLClassLoader) {
	return ImmutableList.copyOf(((URLClassLoader) classloader).getURLs());
	}
	if (classloader.equals(ClassLoader.getSystemClassLoader())) {
	return parseJavaClassPath();
	}
	return ImmutableList.of();
	}

	/**
	* Returns the URLs in the class path specified by the {@code java.class.path} {@linkplain
	* System#getProperty system property}.
	*/
	@VisibleForTesting // TODO(b/65488446): Make this a public API.
	static ImmutableList<URL> parseJavaClassPath() {
	ImmutableList.Builder<URL> urls = ImmutableList.builder();
	for (String entry : Splitter.on(PATH_SEPARATOR.value()).split(JAVA_CLASS_PATH.value())) {
	try {
	try {
	urls.add(new File(entry).toURI().toURL());
	} catch (SecurityException e) { // File.toURI checks to see if the file is a directory
	urls.add(new URL("file", null, new File(entry).getAbsolutePath()));
	}
	} catch (MalformedURLException e) {
	logger.log(WARNING, "malformed classpath entry: " + entry, e);
	}
	}
	return urls.build();
	}

	/**
	* Returns the absolute uri of the Class-Path entry value as specified in <a
	* href="http://docs.oracle.com/javase/8/docs/technotes/guides/jar/jar.html#Main_Attributes">JAR
	* File Specification</a>. Even though the specification only talks about relative urls,
	* absolute urls are actually supported too (for example, in Maven surefire plugin).
	*/
	@VisibleForTesting
	static URL getClassPathEntry(File jarFile, String path) throws MalformedURLException {
	return new URL(jarFile.toURI().toURL(), path);
	}
	}

	@VisibleForTesting
	static final class DefaultScanner extends Scanner {
	private final SetMultimap<ClassLoader, String> resources =
	MultimapBuilder.hashKeys().linkedHashSetValues().build();

	ImmutableSet<ResourceInfo> getResources() {
	ImmutableSet.Builder<ResourceInfo> builder = ImmutableSet.builder();
	for (Entry<ClassLoader, String> entry : resources.entries()) {
	builder.add(ResourceInfo.of(entry.getValue(), entry.getKey()));
	}
	return builder.build();
	}

	@Override
	protected void scanJarFile(ClassLoader classloader, JarFile file) {
	Enumeration<JarEntry> entries = file.entries();
	while (entries.hasMoreElements()) {
	JarEntry entry = entries.nextElement();
	if (entry.isDirectory() \|\| entry.getName().equals(JarFile.MANIFEST_NAME)) {
	continue;
	}
	resources.get(classloader).add(entry.getName());
	}
	}

	@Override
	protected void scanDirectory(ClassLoader classloader, File directory) throws IOException {
	Set<File> currentPath = new HashSet<>();
	currentPath.add(directory.getCanonicalFile());
	scanDirectory(directory, classloader, "", currentPath);
	}

	/**
	* Recursively scan the given directory, adding resources for each file encountered. Symlinks
	* which have already been traversed in the current tree path will be skipped to eliminate
	* cycles; otherwise symlinks are traversed.
	*
	* @param directory the root of the directory to scan
	* @param classloader the classloader that includes resources found in {@code directory}
	* @param packagePrefix resource path prefix inside {@code classloader} for any files found
	* under {@code directory}
	* @param currentPath canonical files already visited in the current directory tree path, for
	* cycle elimination
	*/
	private void scanDirectory(
	File directory, ClassLoader classloader, String packagePrefix, Set<File> currentPath)
	throws IOException {
	File[] files = directory.listFiles();
	if (files == null) {
	logger.warning("Cannot read directory " + directory);
	// IO error, just skip the directory
	return;
	}
	for (File f : files) {
	String name = f.getName();
	if (f.isDirectory()) {
	File deref = f.getCanonicalFile();
	if (currentPath.add(deref)) {
	scanDirectory(deref, classloader, packagePrefix + name + "/", currentPath);
	currentPath.remove(deref);
	}
	} else {
	String resourceName = packagePrefix + name;
	if (!resourceName.equals(JarFile.MANIFEST_NAME)) {
	resources.get(classloader).add(resourceName);
	}
	}
	}
	}
	}

	@VisibleForTesting
	static String getClassName(String filename) {
	int classNameEnd = filename.length() - CLASS_FILE_NAME_EXTENSION.length();
	return filename.substring(0, classNameEnd).replace('/', '.');
	}

	// TODO(benyu): Try java.nio.file.Paths#get() when Guava drops JDK 6 support.
	@VisibleForTesting
	static File toFile(URL url) {
	checkArgument(url.getProtocol().equals("file"));
	try {
	return new File(url.toURI()); // Accepts escaped characters like %20.
	} catch (URISyntaxException e) { // URL.toURI() doesn't escape chars.
	return new File(url.getPath()); // Accepts non-escaped chars like space.
	}
	}
	}