com.google.gwt.thirdparty.guava.common.reflect.ClassPath Maven / Gradle / Ivy
/*
* 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.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Splitter;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.Maps;
import com.google.common.collect.Ordering;
import com.google.common.collect.Sets;
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.Map;
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 javax.annotation.Nullable;
/**
* Scans the source of a {@link ClassLoader} and finds all loadable classes and resources.
*
* @author Ben Yu
* @since 14.0
*/
@Beta
public final class ClassPath {
private static final Logger logger = Logger.getLogger(ClassPath.class.getName());
/** 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 resources;
private ClassPath(ImmutableSet resources) {
this.resources = resources;
}
/**
* Returns a {@code ClassPath} representing all classes and resources loadable from {@code
* classloader} and its parent class loaders.
*
* Currently only {@link URLClassLoader} and only {@code file://} urls are supported.
*
* @throws IOException if the attempt to read class path resources (jar files or directories)
* failed.
*/
public static ClassPath from(ClassLoader classloader) throws IOException {
Scanner scanner = new Scanner();
for (Map.Entry entry : getClassPathEntries(classloader).entrySet()) {
scanner.scan(entry.getKey(), entry.getValue());
}
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 getResources() {
return resources;
}
/** Returns all top level classes loadable from the current class path. */
public ImmutableSet getTopLevelClasses() {
return FluentIterable.from(resources).filter(ClassInfo.class).toSet();
}
/** Returns all top level classes whose package name is {@code packageName}. */
public ImmutableSet getTopLevelClasses(String packageName) {
checkNotNull(packageName);
ImmutableSet.Builder 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 getTopLevelClassesRecursive(String packageName) {
checkNotNull(packageName);
String packagePrefix = packageName + '.';
ImmutableSet.Builder 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) && !resourceName.contains("$")) {
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. */
public final URL url() {
return checkNotNull(loader.getResource(resourceName),
"Failed to load resource: %s", resourceName);
}
/** 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. */
public String getPackageName() {
return Reflection.getPackageName(className);
}
/** Returns the simple name of the underlying class as given in the source code. */
public String getSimpleName() {
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. */
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;
}
}
@VisibleForTesting static ImmutableMap getClassPathEntries(
ClassLoader classloader) {
LinkedHashMap 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));
}
if (classloader instanceof URLClassLoader) {
URLClassLoader urlClassLoader = (URLClassLoader) classloader;
for (URL entry : urlClassLoader.getURLs()) {
URI uri;
try {
uri = entry.toURI();
} catch (URISyntaxException e) {
throw new IllegalArgumentException(e);
}
if (!entries.containsKey(uri)) {
entries.put(uri, classloader);
}
}
}
return ImmutableMap.copyOf(entries);
}
@VisibleForTesting static final class Scanner {
private final ImmutableSortedSet.Builder resources =
new ImmutableSortedSet.Builder(Ordering.usingToString());
private final Set scannedUris = Sets.newHashSet();
ImmutableSortedSet getResources() {
return resources.build();
}
void scan(URI uri, ClassLoader classloader) throws IOException {
if (uri.getScheme().equals("file") && scannedUris.add(uri)) {
scanFrom(new File(uri), classloader);
}
}
@VisibleForTesting void scanFrom(File file, ClassLoader classloader)
throws IOException {
if (!file.exists()) {
return;
}
if (file.isDirectory()) {
scanDirectory(file, classloader);
} else {
scanJar(file, classloader);
}
}
private void scanDirectory(File directory, ClassLoader classloader) throws IOException {
scanDirectory(directory, classloader, "", ImmutableSet.of());
}
private void scanDirectory(
File directory, ClassLoader classloader, String packagePrefix,
ImmutableSet ancestors) throws IOException {
File canonical = directory.getCanonicalFile();
if (ancestors.contains(canonical)) {
// A cycle in the filesystem, for example due to a symbolic link.
return;
}
File[] files = directory.listFiles();
if (files == null) {
logger.warning("Cannot read directory " + directory);
// IO error, just skip the directory
return;
}
ImmutableSet newAncestors = ImmutableSet.builder()
.addAll(ancestors)
.add(canonical)
.build();
for (File f : files) {
String name = f.getName();
if (f.isDirectory()) {
scanDirectory(f, classloader, packagePrefix + name + "/", newAncestors);
} else {
String resourceName = packagePrefix + name;
if (!resourceName.equals(JarFile.MANIFEST_NAME)) {
resources.add(ResourceInfo.of(resourceName, 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 (URI uri : getClassPathFromManifest(file, jarFile.getManifest())) {
scan(uri, classloader);
}
Enumeration entries = jarFile.entries();
while (entries.hasMoreElements()) {
JarEntry entry = entries.nextElement();
if (entry.isDirectory() || entry.getName().equals(JarFile.MANIFEST_NAME)) {
continue;
}
resources.add(ResourceInfo.of(entry.getName(), classloader));
}
} finally {
try {
jarFile.close();
} catch (IOException ignored) {}
}
}
/**
* Returns the class path URIs specified by the {@code Class-Path} manifest attribute, according
* to
* JAR File Specification. If {@code manifest} is null, it means the jar file has no
* manifest, and an empty set will be returned.
*/
@VisibleForTesting static ImmutableSet getClassPathFromManifest(
File jarFile, @Nullable Manifest manifest) {
if (manifest == null) {
return ImmutableSet.of();
}
ImmutableSet.Builder 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)) {
URI uri;
try {
uri = getClassPathEntry(jarFile, path);
} catch (URISyntaxException e) {
// Ignore bad entry
logger.warning("Invalid Class-Path entry: " + path);
continue;
}
builder.add(uri);
}
}
return builder.build();
}
/**
* Returns the absolute uri of the Class-Path entry value as specified in
*
* JAR File Specification. Even though the specification only talks about relative urls,
* absolute urls are actually supported too (for example, in Maven surefire plugin).
*/
@VisibleForTesting static URI getClassPathEntry(File jarFile, String path)
throws URISyntaxException {
URI uri = new URI(path);
if (uri.isAbsolute()) {
return uri;
} else {
return new File(jarFile.getParentFile(), path.replace('/', File.separatorChar)).toURI();
}
}
}
@VisibleForTesting static String getClassName(String filename) {
int classNameEnd = filename.length() - CLASS_FILE_NAME_EXTENSION.length();
return filename.substring(0, classNameEnd).replace('/', '.');
}
}