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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.lang3;
19  
20  import java.net.URL;
21  import java.net.URLClassLoader;
22  import java.util.Arrays;
23  import java.util.Objects;
24  
25  /**
26   * Helps work with {@link ClassLoader}.
27   *
28   * @since 3.10
29   */
30  public class ClassLoaderUtils {
31  
32      private static final URL[] EMPTY_URL_ARRAY = {};
33  
34      /**
35       * Gets the system class loader's URLs, if any.
36       *
37       * @return the system class loader's URLs, if any.
38       * @since 3.13.0
39       */
40      public static URL[] getSystemURLs() {
41          return getURLs(ClassLoader.getSystemClassLoader());
42      }
43  
44      /**
45       * Gets the current thread's context class loader's URLs, if any.
46       *
47       * @return the current thread's context class loader's URLs, if any.
48       * @since 3.13.0
49       */
50      public static URL[] getThreadURLs() {
51          return getURLs(Thread.currentThread().getContextClassLoader());
52      }
53  
54      private static URL[] getURLs(final ClassLoader cl) {
55          return cl instanceof URLClassLoader ? ((URLClassLoader) cl).getURLs() : EMPTY_URL_ARRAY;
56      }
57  
58      /**
59       * Converts the given class loader to a String calling {@link #toString(URLClassLoader)}.
60       *
61       * @param classLoader to URLClassLoader to convert.
62       * @return the formatted string.
63       */
64      public static String toString(final ClassLoader classLoader) {
65          if (classLoader instanceof URLClassLoader) {
66              return toString((URLClassLoader) classLoader);
67          }
68          return Objects.toString(classLoader);
69      }
70  
71      /**
72       * Converts the given URLClassLoader to a String in the format {@code "URLClassLoader.toString() + [URL1, URL2, ...]"}.
73       *
74       * @param classLoader to URLClassLoader to convert.
75       * @return the formatted string.
76       */
77      public static String toString(final URLClassLoader classLoader) {
78          return classLoader != null ? classLoader + Arrays.toString(classLoader.getURLs()) : "null";
79      }
80  
81      /**
82       * Make private in 4.0.
83       *
84       * @deprecated TODO Make private in 4.0.
85       */
86      @Deprecated
87      public ClassLoaderUtils() {
88          // empty
89      }
90  }