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
|
/* LocalClassLoader.java
* =========================================================================
* This file is part of the GrInvIn project - http://www.grinvin.org
*
* Copyright (C) 2005-2008 Universiteit Gent
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* A copy of the GNU General Public License can be found in the file
* LICENSE.txt provided with the source distribution of this program (see
* the META-INF directory in the source jar). This license can also be
* found on the GNU website at http://www.gnu.org/licenses/gpl.html.
*
* If you did not receive a copy of the GNU General Public License along
* with this program, contact the lead developer, or write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
package org.grinvin.util;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
/**
* Class loader which loads classes from a <i>local classpath</i>, i.e., a
* set of directories on the local file system.<p>
* To load a class two different methods can be used:
* <ul>
* <li>Using {@link #loadClass} which is the standard method to retrieve a
* class with a given name.</li>
* <li>Using {@link #loadClassFromFile} to retrieve a class from a given
* class file.</li>
* </ul>
*/
public class LocalClassLoader extends ClassLoader {
//
private static final Logger LOGGER
= Logger.getLogger ("org.grinvin.util");
// TODO: implement findResources(...)
/**
* List of directories searched when loading the class. I.e., the local class
* path.
*/
private List<File> localClasspath;
/**
* Return the local class path, i.e., the directories
* which are currently used to load classes from.<p>
* Note that this method returns an iterable and not a list. This return
* value is intended to be used in a for each loop:
* <pre>
* for (File dir : myClassLoader().getLocalClasspath()) {
* // do something with dir
* }
* </pre>
*/
public Iterable<File> getLocalClasspath () {
return localClasspath; // TODO: should disallow removes
}
//
/**
* Add a directory to the local class path. No action is taken
* when the directory already belongs to the local class path.
* @throws IllegalArgumentException when {@code dir} is not a directory.
*/
public void addDirectory (File dir) {
if (!dir.isDirectory ())
throw new IllegalArgumentException ("Only directories are allowed");
// TODO: support jars
else if (!localClasspath.contains (dir))
localClasspath.add (dir);
}
/**
* Add a base directory which is derived from the given class name
* which is known to reside in the given file.
*/
public void addDirectory (File file, String name) {
int pos = name.lastIndexOf ('.') + 1;
if (file.getName ().equalsIgnoreCase (name.substring (pos)+".class")) {
File dir = file.getParentFile ();
while (pos > 0) {
name = name.substring (0, pos-1);
pos = name.lastIndexOf ('.') + 1;
if (dir != null && ! dir.getName ().equalsIgnoreCase (name.substring (pos)))
return; // could not guess
dir = dir.getParentFile ();
}
if (dir != null)
addDirectory (dir);
}
}
/** Creates a new instance of LocalClassLoader */
public LocalClassLoader () {
super(LocalClassLoader.class.getClassLoader());
localClasspath = new ArrayList<File> ();
}
protected Class<?> findClass (String name) throws ClassNotFoundException {
byte[] data = loadClassData (name);
return defineClass (name, data, 0, data.length);
}
/**
* Load a class file as binary data.
* @throws ClassNotFoundException when an error occurred while loading the file
*/
private byte[] loadClassFile (File file) throws ClassNotFoundException {
long l = file.length ();
if (l > Integer.MAX_VALUE)
throw new RuntimeException ("Class file \'" + file + "\' is too large");
int len = (int) l;
byte[] result = new byte[len];
try {
InputStream is = new FileInputStream (file);
try {
int offs = 0;
int size = is.read (result, offs, len);
while (size > 0) {
offs += size;
len -= size;
size = is.read (result, offs, len);
}
return result;
} finally {
if (is != null)
is.close ();
}
} catch (IOException ex) {
throw new ClassNotFoundException ("Error reading class file", ex);
}
}
/**
* Load a class as binary data.
* @throws ClassNotFoundException when the class file could not be found
* in the current list of directories or when an input-output
* error occurred while loading the file
*/
private byte[] loadClassData (String name) throws ClassNotFoundException {
String path = name.replace ('.', File.separatorChar);
for (File dir : localClasspath) {
File file = new File (dir,path+".class");
if (file.exists ())
return loadClassFile (file);
}
throw new ClassNotFoundException ("Class '" + name + "' not found in local classpath");
}
protected URL findResource (String name) {
for (File dir : localClasspath) {
File file = new File (dir,name);
if (file.exists ()) {
try {
return file.toURI ().toURL ();
} catch (MalformedURLException ex) {
// presently ignored
}
}
}
return null; // resource not found
}
/**
* Load a class from a given class file. Apart from loading the file,
* the system also tries to guess what is the directory for the base
* package of this file and adds it to the local class path. This should
* enable resolution of other local classes referred to by this class.
*/
public Class<?> loadClassFromFile (File file) throws ClassNotFoundException {
byte[] data = loadClassFile (file);
try {
Class<?> clazz = defineClass (null, data, 0, data.length);
resolveClass (clazz);
addDirectory (file, clazz.getName ());
return clazz;
} catch (LinkageError le) {
LOGGER.warning ("Linkage error:" + le);
throw le;
}
}
}
|
