blob: d0ee1686f6a8a8b0008ca084870e46be89f8779f [file] [log] [blame]
/*
* 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.util;
import java.io.InputStream;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.LoaderUtil;
import org.apache.logging.log4j.util.PropertiesUtil;
/**
* Load resources (or images) from various sources.
*/
public final class Loader {
private static final Logger LOGGER = StatusLogger.getLogger();
private static final String TSTR = "Caught Exception while in Loader.getResource. This may be innocuous.";
final static Boolean ignoreTccl =
Boolean.valueOf(PropertiesUtil.getProperties().getStringProperty(LoaderUtil.IGNORE_TCCL_PROPERTY, null));
private Loader() {
}
/**
* Returns the ClassLoader to use.
* @return the ClassLoader.
*/
public static ClassLoader getClassLoader() {
return Loader.getClassLoader(Loader.class, null);
}
// TODO: this method could use some explanation
public static ClassLoader getClassLoader(final Class<?> class1, final Class<?> class2) {
return LoaderUtil.getClassLoader(class1, class2);
}
/**
* Returns the ClassLoader of current thread if possible, or falls back to the system ClassLoader if none is
* available.
*
* @return the TCCL.
* @see org.apache.logging.log4j.util.LoaderUtil#getThreadContextClassLoader()
*/
public static ClassLoader getThreadContextClassLoader() {
return LoaderUtil.getThreadContextClassLoader();
}
/**
* This method will search for {@code resource} in different
* places. The search order is as follows:
*
* <ol>
*
* <li>Search for {@code resource} using the thread context
* class loader under Java2. If that fails, search for
* {@code resource} using the class loader that loaded this
* class ({@code Loader}). Under JDK 1.1, only the the class
* loader that loaded this class ({@code Loader}) is used.</li>
* <li>Try one last time with
* {@code ClassLoader.getSystemResource(resource)}, that is is
* using the system class loader in JDK 1.2 and virtual machine's
* built-in class loader in JDK 1.1.</li>
* </ol>
* @param resource The resource to load.
* @param defaultLoader The default ClassLoader.
* @return A URL to the resource.
*/
public static URL getResource(final String resource, final ClassLoader defaultLoader) {
try {
ClassLoader classLoader = getThreadContextClassLoader();
if (classLoader != null) {
LOGGER.trace("Trying to find [{}] using context class loader {}.", resource, classLoader);
final URL url = classLoader.getResource(resource);
if (url != null) {
return url;
}
}
// We could not find resource. Let us now try with the classloader that loaded this class.
classLoader = Loader.class.getClassLoader();
if (classLoader != null) {
LOGGER.trace("Trying to find [{}] using {} class loader.", resource, classLoader);
final URL url = classLoader.getResource(resource);
if (url != null) {
return url;
}
}
// We could not find resource. Finally try with the default ClassLoader.
if (defaultLoader != null) {
LOGGER.trace("Trying to find [{}] using {} class loader.", resource, defaultLoader);
final URL url = defaultLoader.getResource(resource);
if (url != null) {
return url;
}
}
} catch (final Throwable t) {
//
// can't be InterruptedException or InterruptedIOException
// since not declared, must be error or RuntimeError.
LOGGER.warn(TSTR, t);
}
// Last ditch attempt: get the resource from the class path. It
// may be the case that clazz was loaded by the Extension class
// loader which the parent of the system class loader. Hence the
// code below.
LOGGER.trace("Trying to find [{}] using ClassLoader.getSystemResource().", resource);
return ClassLoader.getSystemResource(resource);
}
/**
* This method will search for {@code resource} in different
* places. The search order is as follows:
*
* <ol>
* <li>Search for {@code resource} using the thread context
* class loader under Java2. If that fails, search for
* {@code resource} using the class loader that loaded this
* class ({@code Loader}). Under JDK 1.1, only the the class
* loader that loaded this class ({@code Loader}) is used.</li>
* <li>Try one last time with
* {@code ClassLoader.getSystemResource(resource)}, that is is
* using the system class loader in JDK 1.2 and virtual machine's
* built-in class loader in JDK 1.1.</li>
* </ol>
* @param resource The resource to load.
* @param defaultLoader The default ClassLoader.
* @return An InputStream to read the resouce.
*/
public static InputStream getResourceAsStream(final String resource, final ClassLoader defaultLoader) {
try {
ClassLoader classLoader = getThreadContextClassLoader();
InputStream is;
if (classLoader != null) {
LOGGER.trace("Trying to find [{}] using context class loader {}.", resource, classLoader);
is = classLoader.getResourceAsStream(resource);
if (is != null) {
return is;
}
}
// We could not find resource. Let us now try with the classloader that loaded this class.
classLoader = Loader.class.getClassLoader();
if (classLoader != null) {
LOGGER.trace("Trying to find [{}] using {} class loader.", resource, classLoader);
is = classLoader.getResourceAsStream(resource);
if (is != null) {
return is;
}
}
// We could not find resource. Finally try with the default ClassLoader.
if (defaultLoader != null) {
LOGGER.trace("Trying to find [{}] using {} class loader.", resource, defaultLoader);
is = defaultLoader.getResourceAsStream(resource);
if (is != null) {
return is;
}
}
} catch (final Throwable t) {
//
// can't be InterruptedException or InterruptedIOException
// since not declared, must be error or RuntimeError.
LOGGER.warn(TSTR, t);
}
// Last ditch attempt: get the resource from the class path. It
// may be the case that clazz was loaded by the Extension class
// loader which the parent of the system class loader. Hence the
// code below.
LOGGER.trace("Trying to find [{}] using ClassLoader.getSystemResource().", resource);
return ClassLoader.getSystemResourceAsStream(resource);
}
/**
* Loads and initializes a named Class using a given ClassLoader.
*
* @param className The class name.
* @param loader The class loader.
* @return The class.
* @throws ClassNotFoundException if the class could not be found.
*/
public static Class<?> initializeClass(final String className, final ClassLoader loader)
throws ClassNotFoundException {
return Class.forName(className, true, loader);
}
/**
* Loads a named Class using a given ClassLoader.
*
* @param className The class name.
* @param loader The class loader.
* @return The class, or null if loader is null.
* @throws ClassNotFoundException if the class could not be found.
*/
public static Class<?> loadClass(final String className, final ClassLoader loader)
throws ClassNotFoundException {
return loader != null ? loader.loadClass(className) : null;
}
/**
* Load a Class in the {@code java.*} namespace by name. Useful for peculiar scenarios typically involving
* Google App Engine.
*
* @param className The class name.
* @return The Class.
* @throws ClassNotFoundException if the Class could not be found.
*/
public static Class<?> loadSystemClass(final String className) throws ClassNotFoundException {
try {
return Class.forName(className, true, ClassLoader.getSystemClassLoader());
} catch (final Throwable t) {
LOGGER.trace("Couldn't use SystemClassLoader. Trying Class.forName({}).", className, t);
return Class.forName(className);
}
}
/**
* Loads and instantiates a Class using the default constructor.
*
* @param className The class name.
* @return new instance of the class.
* @throws ClassNotFoundException if the class isn't available to the usual ClassLoaders
* @throws IllegalAccessException if the class can't be instantiated through a public constructor
* @throws InstantiationException if there was an exception whilst instantiating the class
* @throws InvocationTargetException if there was an exception whilst constructing the class
* @since 2.1
*/
@SuppressWarnings("unchecked")
public static <T> T newInstanceOf(final String className)
throws ClassNotFoundException, IllegalAccessException, InstantiationException, InvocationTargetException {
return newInstanceOf((Class<T>) loadClass(className));
}
/**
* Loads, instantiates, and casts a Class using the default constructor.
*
* @param className The class name.
* @param clazz The class to cast it to.
* @param <T> The type to cast it to.
* @return new instance of the class cast to {@code T}
* @throws ClassNotFoundException if the class isn't available to the usual ClassLoaders
* @throws IllegalAccessException if the class can't be instantiated through a public constructor
* @throws InstantiationException if there was an exception whilst instantiating the class
* @throws InvocationTargetException if there was an exception whilst constructing the class
* @throws ClassCastException if the constructed object isn't type compatible with {@code T}
*/
public static <T> T newCheckedInstanceOf(final String className, final Class<T> clazz)
throws ClassNotFoundException, IllegalAccessException, InvocationTargetException, InstantiationException {
return newInstanceOf(loadClass(className).asSubclass(clazz));
}
/**
* Loads and instantiates a class given by a property name.
*
* @param propertyName The property name to look up a class name for.
* @param clazz The class to cast it to.
* @param <T> The type to cast it to.
* @return new instance of the class given in the property or {@code null} if the property was unset.
* @throws ClassNotFoundException if the class isn't available to the usual ClassLoaders
* @throws IllegalAccessException if the class can't be instantiated through a public constructor
* @throws InstantiationException if there was an exception whilst instantiating the class
* @throws NoSuchMethodException if there isn't a no-args constructor on the class
* @throws InvocationTargetException if there was an exception whilst constructing the class
* @throws ClassCastException if the constructed object isn't type compatible with {@code T}
*/
public static <T> T newCheckedInstanceOfProperty(final String propertyName, final Class<T> clazz)
throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException,
IllegalAccessException {
final String className = PropertiesUtil.getProperties().getStringProperty(propertyName);
ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
try {
Thread.currentThread().setContextClassLoader(getClassLoader());
return LoaderUtil.newCheckedInstanceOfProperty(propertyName, clazz);
} finally {
Thread.currentThread().setContextClassLoader(contextClassLoader);
}
}
/**
* Loads and instantiates a Class using the default constructor.
*
* @param clazz The class.
* @return new instance of the class.
* @throws IllegalAccessException if the class can't be instantiated through a public constructor
* @throws InstantiationException if there was an exception whilst instantiating the class
* @throws InvocationTargetException if there was an exception whilst constructing the class
* @since 2.7
*/
public static <T> T newInstanceOf(final Class<T> clazz)
throws InstantiationException, IllegalAccessException, InvocationTargetException {
try {
return clazz.getConstructor().newInstance();
} catch (final NoSuchMethodException ignored) {
// FIXME: looking at the code for Class.newInstance(), this seems to do the same thing as above
return clazz.newInstance();
}
}
/**
* Determines if a named Class can be loaded or not.
*
* @param className The class name.
* @return {@code true} if the class could be found or {@code false} otherwise.
*/
public static boolean isClassAvailable(final String className) {
ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
try {
Thread.currentThread().setContextClassLoader(getClassLoader());
return LoaderUtil.isClassAvailable(className);
} finally {
Thread.currentThread().setContextClassLoader(contextClassLoader);
}
}
public static boolean isJansiAvailable() {
return isClassAvailable("org.fusesource.jansi.AnsiRenderer");
}
/**
* Loads a class by name. This method respects the {@link #IGNORE_TCCL_PROPERTY} Log4j property. If this property is
* specified and set to anything besides {@code false}, then the default ClassLoader will be used.
*
* @param className The class name.
* @return the Class for the given name.
* @throws ClassNotFoundException if the specified class name could not be found
*/
public static Class<?> loadClass(final String className) throws ClassNotFoundException {
if (ignoreTccl) {
return Class.forName(className);
}
try {
return getClassLoader().loadClass(className);
} catch (final Throwable ignored) {
return Class.forName(className);
}
}
}