001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.lang3;
019
020import java.net.URL;
021import java.net.URLClassLoader;
022import java.util.Arrays;
023import java.util.Objects;
024
025/**
026 * Helps work with {@link ClassLoader}.
027 *
028 * @since 3.10
029 */
030public class ClassLoaderUtils {
031
032    private static final URL[] EMPTY_URL_ARRAY = new URL[] {};
033
034    /**
035     * Gets the system class loader's URLs, if any.
036     *
037     * @return the system class loader's URLs, if any.
038     * @since 3.13.0
039     */
040    public static URL[] getSystemURLs() {
041        return getURLs(ClassLoader.getSystemClassLoader());
042    }
043
044    /**
045     * Gets the current thread's context class loader's URLs, if any.
046     *
047     * @return the current thread's context class loader's URLs, if any.
048     * @since 3.13.0
049     */
050    public static URL[] getThreadURLs() {
051        return getURLs(Thread.currentThread().getContextClassLoader());
052    }
053
054    private static URL[] getURLs(final ClassLoader cl) {
055        return cl instanceof URLClassLoader ? ((URLClassLoader) cl).getURLs() : EMPTY_URL_ARRAY;
056    }
057
058    /**
059     * Converts the given class loader to a String calling {@link #toString(URLClassLoader)}.
060     *
061     * @param classLoader to URLClassLoader to convert.
062     * @return the formatted string.
063     */
064    public static String toString(final ClassLoader classLoader) {
065        if (classLoader instanceof URLClassLoader) {
066            return toString((URLClassLoader) classLoader);
067        }
068        return Objects.toString(classLoader);
069    }
070
071    /**
072     * Converts the given URLClassLoader to a String in the format {@code "URLClassLoader.toString() + [URL1, URL2, ...]"}.
073     *
074     * @param classLoader to URLClassLoader to convert.
075     * @return the formatted string.
076     */
077    public static String toString(final URLClassLoader classLoader) {
078        return classLoader != null ? classLoader + Arrays.toString(classLoader.getURLs()) : "null";
079    }
080}