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.log4j.chainsaw.plugins;
18
19 import org.apache.log4j.chainsaw.prefs.SettingsManager;
20
21 import java.io.File;
22 import java.net.URL;
23 import java.net.URLClassLoader;
24 import java.util.ArrayList;
25 import java.util.List;
26
27 /**
28 * A factory class to create a Classloader that can refenerence jars/classes/resources
29 * within a users plugin directory.
30 * <p>
31 * Currently a work in progress to see if this allows external jars required by
32 * some 3rd party vendors for things like the JMSReceiver.
33 *
34 * @author psmith
35 */
36 public class PluginClassLoaderFactory {
37 private final ClassLoader pluginClassLoader;
38
39 private static final PluginClassLoaderFactory instance = new PluginClassLoaderFactory();
40
41 private PluginClassLoaderFactory() {
42 this.pluginClassLoader = PluginClassLoaderFactory.create(new File(SettingsManager.getInstance().getSettingsDirectory() + File.separator + "plugins"));
43
44 }
45
46 public static PluginClassLoaderFactory getInstance() {
47 return instance;
48 }
49
50 public ClassLoader getClassLoader() {
51 return this.pluginClassLoader;
52 }
53
54 /**
55 * Creates a Classloader that will be able to access any of the classes found
56 * in any .JAR file contained within the specified directory path, PLUS
57 * the actual Plugin directory itself, so it acts like the WEB-INF/classes directory,
58 * any class file in the directory will be accessible
59 *
60 * @param pluginDirectory
61 * @return
62 * @throws IllegalArgumentException if the pluginDirectory is null, does not exist, or cannot be read
63 * @throws RuntimeException if turning a File into a URL failed, which would be very unexpected
64 */
65 private static final ClassLoader create(File pluginDirectory) {
66 if (pluginDirectory == null || !pluginDirectory.exists() || !pluginDirectory.canRead()) {
67 return PluginClassLoaderFactory.class.getClassLoader();
68 }
69
70 String[] strings = pluginDirectory.list((dir, name) -> name.toUpperCase().endsWith(".JAR"));
71
72
73 List<URL> list = new ArrayList<>();
74 // add the plugin directory as a resource loading path
75 try {
76 list.add(pluginDirectory.toURI().toURL());
77 } catch (Exception e) {
78 throw new RuntimeException(e.getMessage());
79 }
80 if (strings != null) {
81 for (String name : strings) {
82 File file = new File(pluginDirectory, name);
83 try {
84 list.add(file.toURI().toURL());
85 System.out.println("Added " + file.getAbsolutePath()
86 + " to Plugin class loader list");
87 } catch (Exception e) {
88 System.err.println("Failed to retrieve the URL for file: "
89 + file.getAbsolutePath());
90 throw new RuntimeException(e.getMessage());
91 }
92 }
93 }
94 ClassLoader parent = PluginClassLoaderFactory.class.getClassLoader();
95 URL[] urls = (URL[]) list.toArray(new URL[list.size()]);
96 return new URLClassLoader(urls, parent);
97 }
98
99 }