1 /**
2 * Copyright 2003-2007 Greg Luck
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package net.sf.ehcache.util;
18
19 import net.sf.ehcache.CacheException;
20
21 /**
22 * Keeps all classloading in ehcache consistent.
23 *
24 * @author Greg Luck
25 * @version $Id: ClassLoaderUtil.java 512 2007-07-10 09:18:45Z gregluck $
26 */
27 public final class ClassLoaderUtil {
28
29 /**
30 * Utility class.
31 */
32 private ClassLoaderUtil() {
33 //noop
34 }
35
36 /**
37 * Gets the <code>ClassLoader</code> that all classes in ehcache, and extensions, should
38 * use for classloading. All ClassLoading in ehcache should use this one. This is the only
39 * thing that seems to work for all of the class loading situations found in the wild.
40 * @return the thread context class loader.
41 */
42 public static ClassLoader getStandardClassLoader() {
43 return Thread.currentThread().getContextClassLoader();
44 }
45
46 /**
47 * Gets a fallback <code>ClassLoader</code> that all classes in ehcache, and extensions,
48 * should use for classloading. This is used if the context class loader does not work.
49 * @return the <code>ClassLoaderUtil.class.getClassLoader();</code>
50 */
51 public static ClassLoader getFallbackClassLoader() {
52 return ClassLoaderUtil.class.getClassLoader();
53 }
54
55 /**
56 * Creates a new class instance. Logs errors along the way. Classes are loaded using the
57 * ehcache standard classloader.
58 *
59 * @param className a fully qualified class name
60 * @return null if the instance cannot be loaded
61 */
62 public static Object createNewInstance(String className) throws CacheException {
63 Class clazz;
64 Object newInstance;
65 try {
66 clazz = Class.forName(className, true, getStandardClassLoader());
67 } catch (ClassNotFoundException e) {
68 //try fallback
69 try {
70 clazz = Class.forName(className, true, getFallbackClassLoader());
71 } catch (ClassNotFoundException ex) {
72 throw new CacheException("Unable to load class " + className +
73 ". Initial cause was " + e.getMessage(), e);
74 }
75 }
76
77 try {
78 newInstance = clazz.newInstance();
79 } catch (IllegalAccessException e) {
80 throw new CacheException("Unable to load class " + className +
81 ". Initial cause was " + e.getMessage(), e);
82 } catch (InstantiationException e) {
83 throw new CacheException("Unable to load class " + className +
84 ". Initial cause was " + e.getMessage(), e);
85 }
86 return newInstance;
87 }
88
89
90 }