1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/******************************************************************************
* Copyright (c) 2006, 2010 VMware Inc., Oracle Inc.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Apache License v2.0 which accompanies this distribution.
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html and the Apache License v2.0
* is available at http://www.opensource.org/licenses/apache2.0.php.
* You may elect to redistribute this code under either of these licenses.
*
* Contributors:
* VMware Inc.
* Oracle Inc.
*****************************************************************************/
package org.eclipse.gemini.blueprint.util;
import org.apache.commons.logging.Log;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleReference;
import org.springframework.util.Assert;
import java.io.IOException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Enumeration;
import java.util.NoSuchElementException;
/**
* ClassLoader backed by an OSGi bundle. Provides the ability to use a separate
* class loader as fall back.
*
* Contains facilities for tracing class loading behaviour so that issues can be
* easily resolved.
*
* For debugging please see {@link DebugUtils}.
*
* @author Adrian Colyer
* @author Andy Piper
* @author Costin Leau
*/
public class BundleDelegatingClassLoader extends ClassLoader implements BundleReference {
private static final Enumeration<URL> EMPTY_RESOURCES = new Enumeration<URL>() {
public boolean hasMoreElements() {
return false;
}
public URL nextElement() {
throw new NoSuchElementException();
}
};
/**
* Transparently enumerates across two enumerations.
*/
private static class CombinedEnumeration<T> implements Enumeration<T> {
private final Enumeration<T> e1;
private final Enumeration<T> e2;
public CombinedEnumeration(Enumeration<T> e1, Enumeration<T> e2) {
this.e1 = e1;
this.e2 = e2;
}
public boolean hasMoreElements() {
return e1.hasMoreElements() || e2.hasMoreElements();
}
public T nextElement() {
if (e1.hasMoreElements()) {
return e1.nextElement();
}
if (e2.hasMoreElements()) {
return e2.nextElement();
}
throw new NoSuchElementException();
}
}
/** use degradable logger */
private static final Log log = LogUtils.createLogger(BundleDelegatingClassLoader.class);
private final ClassLoader bridge;
private final Bundle backingBundle;
/**
* Factory method for creating a class loader over the given bundle.
*
* @param aBundle bundle to use for class loading and resource acquisition
* @return class loader adapter over the given bundle
*/
public static BundleDelegatingClassLoader createBundleClassLoaderFor(Bundle aBundle) {
return createBundleClassLoaderFor(aBundle, null);
}
/**
* Factory method for creating a class loader over the given bundle and with
* a given class loader as fall-back. In case the bundle cannot find a class
* or locate a resource, the given class loader will be used as fall back.
*
* @param bundle bundle used for class loading and resource acquisition
* @param bridge class loader used as fall back in case the bundle cannot
* load a class or find a resource. Can be <code>null</code>
* @return class loader adapter over the given bundle and class loader
*/
public static BundleDelegatingClassLoader createBundleClassLoaderFor(final Bundle bundle, final ClassLoader bridge) {
return AccessController.doPrivileged(new PrivilegedAction<BundleDelegatingClassLoader>() {
public BundleDelegatingClassLoader run() {
return new BundleDelegatingClassLoader(bundle, bridge);
}
});
}
/**
* Private constructor.
*
* Constructs a new <code>BundleDelegatingClassLoader</code> instance.
*
* @param bundle
* @param bridgeLoader
*/
protected BundleDelegatingClassLoader(Bundle bundle, ClassLoader bridgeLoader) {
super(null);
Assert.notNull(bundle, "bundle should be non-null");
this.backingBundle = bundle;
this.bridge = bridgeLoader;
}
protected Class<?> findClass(String name) throws ClassNotFoundException {
try {
return this.backingBundle.loadClass(name);
}
catch (ClassNotFoundException cnfe) {
DebugUtils.debugClassLoading(backingBundle, name, null);
throw new ClassNotFoundException(name + " not found from bundle [" + backingBundle.getSymbolicName() + "]",
cnfe);
}
catch (NoClassDefFoundError ncdfe) {
// This is almost always an error
// This is caused by a dependent class failure,
// so make sure we search for the right one.
String cname = ncdfe.getMessage().replace('/', '.');
DebugUtils.debugClassLoading(backingBundle, cname, name);
NoClassDefFoundError e = new NoClassDefFoundError(name + " not found from bundle ["
+ OsgiStringUtils.nullSafeNameAndSymName(backingBundle) + "]");
e.initCause(ncdfe);
throw e;
}
}
protected URL findResource(String name) {
boolean trace = log.isTraceEnabled();
if (trace)
log.trace("Looking for resource " + name);
URL url = this.backingBundle.getResource(name);
if (trace && url != null)
log.trace("Found resource " + name + " at " + url);
return url;
}
@SuppressWarnings("unchecked")
protected Enumeration<URL> findResources(String name) throws IOException {
boolean trace = log.isTraceEnabled();
if (trace)
log.trace("Looking for resources " + name);
Enumeration<URL> enm = this.backingBundle.getResources(name);
if (trace && enm != null && enm.hasMoreElements())
log.trace("Found resource " + name + " at " + this.backingBundle.getLocation());
return enm;
}
@Override
public Enumeration<URL> getResources(String name) throws IOException {
@SuppressWarnings("unchecked")
Enumeration<URL> resources = this.backingBundle.getResources(name);
if (this.bridge != null) {
Enumeration<URL> bridgeResources = this.bridge.getResources(name);
if (resources == null) {
resources = bridgeResources;
} else if (bridgeResources != null){
resources = new CombinedEnumeration<URL>(resources, bridgeResources);
}
}
// Classloader contract: Never return null but rather an empty enumeration.
return resources != null ? resources : EMPTY_RESOURCES;
}
public URL getResource(String name) {
URL resource = findResource(name);
if (bridge != null && resource == null) {
resource = bridge.getResource(name);
}
return resource;
}
protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
Class<?> clazz = null;
try {
clazz = findClass(name);
}
catch (ClassNotFoundException cnfe) {
if (bridge != null)
clazz = bridge.loadClass(name);
else
throw cnfe;
}
if (resolve) {
resolveClass(clazz);
}
return clazz;
}
public String toString() {
return "BundleDelegatingClassLoader for [" + OsgiStringUtils.nullSafeNameAndSymName(backingBundle) + "]";
}
/**
* Returns the bundle to which this class loader delegates calls to.
*
* @return the backing bundle
*/
@Override
public Bundle getBundle() {
return backingBundle;
}
}
|
