org.apache.logging.log4j.core.config.plugins.util.ResolverUtil Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.config.plugins.util;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarInputStream;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.status.StatusLogger;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.wiring.BundleWiring;
/**
*
* ResolverUtil is used to locate classes that are available in the/a class path and meet arbitrary conditions. The two
* most common conditions are that a class implements/extends another class, or that is it annotated with a specific
* annotation. However, through the use of the {@link Test} class it is possible to search using arbitrary conditions.
*
*
*
* A ClassLoader is used to locate all locations (directories and jar files) in the class path that contain classes
* within certain packages, and then to load those classes and check them. By default the ClassLoader returned by
* {@code Thread.currentThread().getContextClassLoader()} is used, but this can be overridden by calling
* {@link #setClassLoader(ClassLoader)} prior to invoking any of the {@code find()} methods.
*
*
*
* General searches are initiated by calling the {@link #find(ResolverUtil.Test, String...)} method and supplying a
* package name and a Test instance. This will cause the named package and all sub-packages to be scanned for
* classes that meet the test. There are also utility methods for the common use cases of scanning multiple packages for
* extensions of particular classes, or classes annotated with a specific annotation.
*
*
*
* The standard usage pattern for the ResolverUtil class is as follows:
*
*
*
* ResolverUtil<ActionBean> resolver = new ResolverUtil<ActionBean>();
* resolver.findImplementation(ActionBean.class, pkg1, pkg2);
* resolver.find(new CustomTest(), pkg1);
* resolver.find(new CustomTest(), pkg2);
* Collection<ActionBean> beans = resolver.getClasses();
*
*
*
* This class was copied and modified from Stripes - http://stripes.mc4j.org/confluence/display/stripes/Home
*
*/
public class ResolverUtil {
/** An instance of Log to use for logging in this class. */
private static final Logger LOGGER = StatusLogger.getLogger();
private static final String VFSZIP = "vfszip";
private static final String BUNDLE_RESOURCE = "bundleresource";
/** The set of matches being accumulated. */
private final Set> classMatches = new HashSet<>();
/** The set of matches being accumulated. */
private final Set resourceMatches = new HashSet<>();
/**
* The ClassLoader to use when looking for classes. If null then the ClassLoader returned by
* Thread.currentThread().getContextClassLoader() will be used.
*/
private ClassLoader classloader;
/**
* Provides access to the classes discovered so far. If no calls have been made to any of the {@code find()}
* methods, this set will be empty.
*
* @return the set of classes that have been discovered.
*/
public Set> getClasses() {
return classMatches;
}
/**
* Returns the matching resources.
*
* @return A Set of URIs that match the criteria.
*/
public Set getResources() {
return resourceMatches;
}
/**
* Returns the classloader that will be used for scanning for classes. If no explicit ClassLoader has been set by
* the calling, the context class loader will be used.
*
* @return the ClassLoader that will be used to scan for classes
*/
public ClassLoader getClassLoader() {
return classloader != null ? classloader : (classloader = Loader.getClassLoader(ResolverUtil.class, null));
}
/**
* Sets an explicit ClassLoader that should be used when scanning for classes. If none is set then the context
* classloader will be used.
*
* @param aClassloader
* a ClassLoader to use when scanning for classes
*/
public void setClassLoader(final ClassLoader aClassloader) {
this.classloader = aClassloader;
}
/**
* Attempts to discover classes that pass the test. Accumulated classes can be accessed by calling
* {@link #getClasses()}.
*
* @param test
* the test to determine matching classes
* @param packageNames
* one or more package names to scan (including subpackages) for classes
*/
public void find(final Test test, final String... packageNames) {
if (packageNames == null) {
return;
}
for (final String pkg : packageNames) {
findInPackage(test, pkg);
}
}
/**
* Scans for classes starting at the package provided and descending into subpackages. Each class is offered up to
* the Test as it is discovered, and if the Test returns true the class is retained. Accumulated classes can be
* fetched by calling {@link #getClasses()}.
*
* @param test
* an instance of {@link Test} that will be used to filter classes
* @param packageName
* the name of the package from which to start scanning for classes, e.g. {@code net.sourceforge.stripes}
*/
public void findInPackage(final Test test, String packageName) {
packageName = packageName.replace('.', '/');
final ClassLoader loader = getClassLoader();
Enumeration urls;
try {
urls = loader.getResources(packageName);
} catch (final IOException ioe) {
LOGGER.warn("Could not read package: " + packageName, ioe);
return;
}
while (urls.hasMoreElements()) {
try {
final URL url = urls.nextElement();
final String urlPath = extractPath(url);
LOGGER.info("Scanning for classes in [" + urlPath + "] matching criteria: " + test);
// Check for a jar in a war in JBoss
if (VFSZIP.equals(url.getProtocol())) {
final String path = urlPath.substring(0, urlPath.length() - packageName.length() - 2);
final URL newURL = new URL(url.getProtocol(), url.getHost(), path);
@SuppressWarnings("resource")
final JarInputStream stream = new JarInputStream(newURL.openStream());
try {
loadImplementationsInJar(test, packageName, path, stream);
} finally {
close(stream, newURL);
}
} else if (BUNDLE_RESOURCE.equals(url.getProtocol())) {
loadImplementationsInBundle(test, packageName);
} else {
final File file = new File(urlPath);
if (file.isDirectory()) {
loadImplementationsInDirectory(test, packageName, file);
} else {
loadImplementationsInJar(test, packageName, file);
}
}
} catch (final IOException | URISyntaxException ioe) {
LOGGER.warn("could not read entries", ioe);
}
}
}
String extractPath(final URL url) throws UnsupportedEncodingException, URISyntaxException {
String urlPath = url.getPath(); // same as getFile but without the Query portion
// System.out.println(url.getProtocol() + "->" + urlPath);
// I would be surprised if URL.getPath() ever starts with "jar:" but no harm in checking
if (urlPath.startsWith("jar:")) {
urlPath = urlPath.substring(4);
}
// For jar: URLs, the path part starts with "file:"
if (urlPath.startsWith("file:")) {
urlPath = urlPath.substring(5);
}
// If it was in a JAR, grab the path to the jar
if (urlPath.indexOf('!') > 0) {
urlPath = urlPath.substring(0, urlPath.indexOf('!'));
}
// LOG4J2-445
// Finally, decide whether to URL-decode the file name or not...
final String protocol = url.getProtocol();
final List neverDecode = Arrays.asList(VFSZIP, BUNDLE_RESOURCE);
if (neverDecode.contains(protocol)) {
return urlPath;
}
final String cleanPath = new URI(urlPath).getPath();
if (new File(cleanPath).exists()) {
// if URL-encoded file exists, don't decode it
return cleanPath;
}
return URLDecoder.decode(urlPath, StandardCharsets.UTF_8.name());
}
private void loadImplementationsInBundle(final Test test, final String packageName) {
final BundleWiring wiring = FrameworkUtil.getBundle(ResolverUtil.class).adapt(BundleWiring.class);
final Collection list = wiring.listResources(packageName, "*.class",
BundleWiring.LISTRESOURCES_RECURSE);
for (final String name : list) {
addIfMatching(test, name);
}
}
/**
* Finds matches in a physical directory on a filesystem. Examines all files within a directory - if the File object
* is not a directory, and ends with .class the file is loaded and tested to see if it is acceptable
* according to the Test. Operates recursively to find classes within a folder structure matching the package
* structure.
*
* @param test
* a Test used to filter the classes that are discovered
* @param parent
* the package name up to this directory in the package hierarchy. E.g. if /classes is in the classpath and
* we wish to examine files in /classes/org/apache then the values of parent would be
* org/apache
* @param location
* a File object representing a directory
*/
private void loadImplementationsInDirectory(final Test test, final String parent, final File location) {
final File[] files = location.listFiles();
if (files == null) {
return;
}
StringBuilder builder;
for (final File file : files) {
builder = new StringBuilder();
builder.append(parent).append('/').append(file.getName());
final String packageOrClass = parent == null ? file.getName() : builder.toString();
if (file.isDirectory()) {
loadImplementationsInDirectory(test, packageOrClass, file);
} else if (isTestApplicable(test, file.getName())) {
addIfMatching(test, packageOrClass);
}
}
}
private boolean isTestApplicable(final Test test, final String path) {
return test.doesMatchResource() || path.endsWith(".class") && test.doesMatchClass();
}
/**
* Finds matching classes within a jar files that contains a folder structure matching the package structure. If the
* File is not a JarFile or does not exist a warning will be logged, but no error will be raised.
*
* @param test
* a Test used to filter the classes that are discovered
* @param parent
* the parent package under which classes must be in order to be considered
* @param jarFile
* the jar file to be examined for classes
*/
private void loadImplementationsInJar(final Test test, final String parent, final File jarFile) {
@SuppressWarnings("resource")
JarInputStream jarStream = null;
try {
jarStream = new JarInputStream(new FileInputStream(jarFile));
loadImplementationsInJar(test, parent, jarFile.getPath(), jarStream);
} catch (final FileNotFoundException ex) {
LOGGER.error("Could not search jar file '" + jarFile + "' for classes matching criteria: " + test
+ " file not found", ex);
} catch (final IOException ioe) {
LOGGER.error("Could not search jar file '" + jarFile + "' for classes matching criteria: " + test
+ " due to an IOException", ioe);
} finally {
close(jarStream, jarFile);
}
}
/**
* @param jarStream
* @param source
*/
private void close(final JarInputStream jarStream, final Object source) {
if (jarStream != null) {
try {
jarStream.close();
} catch (final IOException e) {
LOGGER.error("Error closing JAR file stream for {}", source, e);
}
}
}
/**
* Finds matching classes within a jar files that contains a folder structure matching the package structure. If the
* File is not a JarFile or does not exist a warning will be logged, but no error will be raised.
*
* @param test
* a Test used to filter the classes that are discovered
* @param parent
* the parent package under which classes must be in order to be considered
* @param stream
* The jar InputStream
*/
private void loadImplementationsInJar(final Test test, final String parent, final String path,
final JarInputStream stream) {
try {
JarEntry entry;
while ((entry = stream.getNextJarEntry()) != null) {
final String name = entry.getName();
if (!entry.isDirectory() && name.startsWith(parent) && isTestApplicable(test, name)) {
addIfMatching(test, name);
}
}
} catch (final IOException ioe) {
LOGGER.error("Could not search jar file '" + path + "' for classes matching criteria: " + test
+ " due to an IOException", ioe);
}
}
/**
* Add the class designated by the fully qualified class name provided to the set of resolved classes if and only if
* it is approved by the Test supplied.
*
* @param test
* the test used to determine if the class matches
* @param fqn
* the fully qualified name of a class
*/
protected void addIfMatching(final Test test, final String fqn) {
try {
final ClassLoader loader = getClassLoader();
if (test.doesMatchClass()) {
final String externalName = fqn.substring(0, fqn.indexOf('.')).replace('/', '.');
if (LOGGER.isDebugEnabled()) {
LOGGER.debug("Checking to see if class " + externalName + " matches criteria [" + test + ']');
}
final Class type = loader.loadClass(externalName);
if (test.matches(type)) {
classMatches.add(type);
}
}
if (test.doesMatchResource()) {
URL url = loader.getResource(fqn);
if (url == null) {
url = loader.getResource(fqn.substring(1));
}
if (url != null && test.matches(url.toURI())) {
resourceMatches.add(url.toURI());
}
}
} catch (final Throwable t) {
LOGGER.warn("Could not examine class '" + fqn, t);
}
}
/**
* A simple interface that specifies how to test classes to determine if they are to be included in the results
* produced by the ResolverUtil.
*/
public interface Test {
/**
* Will be called repeatedly with candidate classes. Must return True if a class is to be included in the
* results, false otherwise.
*
* @param type
* The Class to match against.
* @return true if the Class matches.
*/
boolean matches(Class type);
/**
* Test for a resource.
*
* @param resource
* The URI to the resource.
* @return true if the resource matches.
*/
boolean matches(URI resource);
boolean doesMatchClass();
boolean doesMatchResource();
}
}