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 package org.apache.logging.log4j.util;
18
19 import java.security.AccessController;
20 import java.security.PrivilegedAction;
21
22 /**
23 * <em>Consider this class private.</em> Utility class for ClassLoaders.
24 * @see ClassLoader
25 * @see Thread#getContextClassLoader()
26 */
27 // TODO: migrate any other useful methods from Loader in log4j-core
28 public final class LoaderUtil {
29 private LoaderUtil() {}
30
31 private static final PrivilegedAction<ClassLoader> TCCL_GETTER = new ThreadContextClassLoaderGetter();
32
33 static {
34 final SecurityManager sm = System.getSecurityManager();
35 if (sm != null) {
36 sm.checkPermission(new RuntimePermission("getClassLoader"));
37 }
38 }
39
40 /**
41 * Gets the current Thread ClassLoader. Returns the system ClassLoader if the TCCL is {@code null}.
42 *
43 * @return the current ThreadContextClassLoader.
44 */
45 public static ClassLoader getThreadContextClassLoader() {
46 return System.getSecurityManager() == null
47 ? TCCL_GETTER.run()
48 : AccessController.doPrivileged(TCCL_GETTER);
49 }
50
51 private static class ThreadContextClassLoaderGetter implements PrivilegedAction<ClassLoader> {
52 @Override
53 public ClassLoader run() {
54 final ClassLoader cl = Thread.currentThread().getContextClassLoader();
55 // if the TCCL is null, that means we're using the system CL
56 return cl == null ? ClassLoader.getSystemClassLoader() : cl;
57 }
58 }
59 }