1 package org.apache.maven.shared.transfer.project;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import org.codehaus.plexus.classworlds.realm.ClassRealm;
23 import org.slf4j.Logger;
24 import org.slf4j.LoggerFactory;
25
26 /**
27 * This util class will import the Aether library available from the installed Maven distribution. It will do nothing if
28 * it is called from outside of a ClassRealm.
29 *
30 * @since 0.11.1
31 * @author Gabriel Belingueres <a href="mailto:belingueres@gmail.com">belingueres@gmail.com</a>
32 */
33 public class MavenAetherUtils
34 {
35
36 private static final Logger LOGGER = LoggerFactory.getLogger( MavenAetherUtils.class );
37
38 private static final String NO_SUCH_REALM_EXCEPTION = "org.codehaus.plexus.classworlds.realm.NoSuchRealmException";
39
40 /**
41 * Import the core Aether library from the maven distribution.
42 */
43 public static void importAetherLibrary()
44 {
45 ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
46 if ( isClassRealm( classLoader ) )
47 {
48 importAether( classLoader );
49 }
50 }
51
52 /**
53 * Imports aether-util library from the user's Maven distribution.
54 * <p>
55 * PRECONDITION: the classLoader parameter is an instance of ClassRealm.
56 * </p>
57 *
58 * @param classLoader the Classloader which needs to access aether-util.
59 */
60 private static void importAether( ClassLoader classLoader )
61 {
62 ClassRealm classRealm = (ClassRealm) classLoader;
63 try
64 {
65 classRealm.importFrom( "plexus.core", "org.eclipse.aether.util" );
66 }
67 catch ( Exception e )
68 {
69 if ( NO_SUCH_REALM_EXCEPTION.equals( e.getClass().getCanonicalName() ) )
70 {
71 LOGGER.info( "'plexus.core' ClassRealm could not be found. "
72 + "Ignore this message if you are using the library outside of a Maven execution.", e );
73 }
74 else
75 {
76 // another exception
77 LOGGER.error( "Unexpected exception when importing Aether library to the '{}' ClassRealm", classLoader,
78 e );
79 }
80 }
81 }
82
83 /**
84 * Using reflection, check if the Classloader is actually an instance of a ClassRealm.
85 *
86 * @param classLoader the Classloader to test.
87 * @return true if it an instance of ClassRealm; false otherwise.
88 */
89 private static boolean isClassRealm( ClassLoader classLoader )
90 {
91 for ( Class<?> clazz = classLoader.getClass(); clazz != null; clazz = clazz.getSuperclass() )
92 {
93 if ( "org.codehaus.plexus.classworlds.realm.ClassRealm".equals( clazz.getCanonicalName() ) )
94 {
95 return true;
96 }
97 }
98 return false;
99 }
100 }