forked from spring-projects/spring-boot
/
RestartClassLoader.java
229 lines (202 loc) · 6.87 KB
/
RestartClassLoader.java
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
/*
* Copyright 2012-2021 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.boot.devtools.restart.classloader;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.Enumeration;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.boot.devtools.restart.classloader.ClassLoaderFile.Kind;
import org.springframework.core.SmartClassLoader;
import org.springframework.util.Assert;
/**
* Disposable {@link ClassLoader} used to support application restarting. Provides parent
* last loading for the specified URLs.
*
* @author Andy Clement
* @author Phillip Webb
* @since 1.3.0
*/
public class RestartClassLoader extends URLClassLoader implements SmartClassLoader {
private final Log logger;
private final ClassLoaderFileRepository updatedFiles;
/**
* Create a new {@link RestartClassLoader} instance.
* @param parent the parent classloader
* @param urls the urls managed by the classloader
*/
public RestartClassLoader(ClassLoader parent, URL[] urls) {
this(parent, urls, ClassLoaderFileRepository.NONE);
}
/**
* Create a new {@link RestartClassLoader} instance.
* @param parent the parent classloader
* @param updatedFiles any files that have been updated since the JARs referenced in
* URLs were created.
* @param urls the urls managed by the classloader
*/
public RestartClassLoader(ClassLoader parent, URL[] urls, ClassLoaderFileRepository updatedFiles) {
this(parent, urls, updatedFiles, LogFactory.getLog(RestartClassLoader.class));
}
/**
* Create a new {@link RestartClassLoader} instance.
* @param parent the parent classloader
* @param updatedFiles any files that have been updated since the JARs referenced in
* URLs were created.
* @param urls the urls managed by the classloader
* @param logger the logger used for messages
*/
public RestartClassLoader(ClassLoader parent, URL[] urls, ClassLoaderFileRepository updatedFiles, Log logger) {
super(urls, parent);
Assert.notNull(parent, "Parent must not be null");
Assert.notNull(updatedFiles, "UpdatedFiles must not be null");
Assert.notNull(logger, "Logger must not be null");
this.updatedFiles = updatedFiles;
this.logger = logger;
if (logger.isDebugEnabled()) {
logger.debug("Created RestartClassLoader " + toString());
}
}
@Override
public Enumeration<URL> getResources(String name) throws IOException {
// Use the parent since we're shadowing resource and we don't want duplicates
Enumeration<URL> resources = getParent().getResources(name);
ClassLoaderFile file = this.updatedFiles.getFile(name);
if (file != null) {
// Assume that we're replacing just the first item
if (resources.hasMoreElements()) {
resources.nextElement();
}
if (file.getKind() != Kind.DELETED) {
return new CompoundEnumeration<>(createFileUrl(name, file), resources);
}
}
return resources;
}
@Override
public URL getResource(String name) {
ClassLoaderFile file = this.updatedFiles.getFile(name);
if (file != null && file.getKind() == Kind.DELETED) {
return null;
}
URL resource = findResource(name);
if (resource != null) {
return resource;
}
return getParent().getResource(name);
}
@Override
public URL findResource(String name) {
final ClassLoaderFile file = this.updatedFiles.getFile(name);
if (file == null) {
return super.findResource(name);
}
if (file.getKind() == Kind.DELETED) {
return null;
}
return AccessController.doPrivileged((PrivilegedAction<URL>) () -> createFileUrl(name, file));
}
@Override
public Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
String path = name.replace('.', '/').concat(".class");
ClassLoaderFile file = this.updatedFiles.getFile(path);
if (file != null && file.getKind() == Kind.DELETED) {
throw new ClassNotFoundException(name);
}
synchronized (getClassLoadingLock(name)) {
Class<?> loadedClass = findLoadedClass(name);
if (loadedClass == null) {
try {
loadedClass = findClass(name);
}
catch (ClassNotFoundException ex) {
loadedClass = Class.forName(name, false, getParent());
}
}
if (resolve) {
resolveClass(loadedClass);
}
return loadedClass;
}
}
@Override
protected Class<?> findClass(String name) throws ClassNotFoundException {
String path = name.replace('.', '/').concat(".class");
final ClassLoaderFile file = this.updatedFiles.getFile(path);
if (file == null) {
return super.findClass(name);
}
if (file.getKind() == Kind.DELETED) {
throw new ClassNotFoundException(name);
}
return AccessController.doPrivileged((PrivilegedAction<Class<?>>) () -> {
byte[] bytes = file.getContents();
return defineClass(name, bytes, 0, bytes.length);
});
}
@Override
public Class<?> publicDefineClass(String name, byte[] b, ProtectionDomain protectionDomain) {
return defineClass(name, b, 0, b.length, protectionDomain);
}
private URL createFileUrl(String name, ClassLoaderFile file) {
try {
return new URL("reloaded", null, -1, "/" + name, new ClassLoaderFileURLStreamHandler(file));
}
catch (MalformedURLException ex) {
throw new IllegalStateException(ex);
}
}
@Override
protected void finalize() throws Throwable {
if (this.logger.isDebugEnabled()) {
this.logger.debug("Finalized classloader " + toString());
}
super.finalize();
}
@Override
public boolean isClassReloadable(Class<?> classType) {
return (classType.getClassLoader() instanceof RestartClassLoader);
}
/**
* Compound {@link Enumeration} that adds an additional item to the front.
*/
private static class CompoundEnumeration<E> implements Enumeration<E> {
private E firstElement;
private final Enumeration<E> enumeration;
CompoundEnumeration(E firstElement, Enumeration<E> enumeration) {
this.firstElement = firstElement;
this.enumeration = enumeration;
}
@Override
public boolean hasMoreElements() {
return (this.firstElement != null || this.enumeration.hasMoreElements());
}
@Override
public E nextElement() {
if (this.firstElement == null) {
return this.enumeration.nextElement();
}
E element = this.firstElement;
this.firstElement = null;
return element;
}
}
}