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}