    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;
    023
    024/**
    025 * Helps work with {@link ClassLoader}.
    026 *
    027 * @since 3.10
    028 */
    029public class ClassLoaderUtils {
    030
    031    private static final URL[] EMPTY_URL_ARRAY = new URL[] {};
    032
    033    /**
    034     * Gets the system class loader's URLs, if any.
    035     *
    036     * @return the system class loader's URLs, if any.
    037     * @since 3.13.0
    038     */
    039    public static URL[] getSystemURLs() {
    040        return getURLs(ClassLoader.getSystemClassLoader());
    041    }
    042
    043    /**
    044     * Gets the current thread's context class loader's URLs, if any.
    045     *
    046     * @return the current thread's context class loader's URLs, if any.
    047     * @since 3.13.0
    048     */
    049    public static URL[] getThreadURLs() {
    050        return getURLs(Thread.currentThread().getContextClassLoader());
    051    }
    052
    053    private static URL[] getURLs(final ClassLoader cl) {
    054        return cl instanceof URLClassLoader ? ((URLClassLoader) cl).getURLs() : EMPTY_URL_ARRAY;
    055    }
    056
    057    /**
    058     * Converts the given class loader to a String calling {@link #toString(URLClassLoader)}.
    059     *
    060     * @param classLoader to URLClassLoader to convert.
    061     * @return the formatted string.
    062     */
    063    public static String toString(final ClassLoader classLoader) {
    064        if (classLoader instanceof URLClassLoader) {
    065            return toString((URLClassLoader) classLoader);
    066        }
    067        return classLoader.toString();
    068    }
    069
    070    /**
    071     * Converts the given URLClassLoader to a String in the format {@code "URLClassLoader.toString() + [URL1, URL2, ...]"}.
    072     *
    073     * @param classLoader to URLClassLoader to convert.
    074     * @return the formatted string.
    075     */
    076    public static String toString(final URLClassLoader classLoader) {
    077        return classLoader + Arrays.toString(classLoader.getURLs());
    078    }
    079}