1 /*
2 * Copyright (c) 2018 by SAP AG, Walldorf, Germany.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 package test;
26
27 import java.io.IOException;
28 import java.io.InputStream;
29 import java.net.URL;
30 import java.security.SecureClassLoader;
31 import java.util.Arrays;
32 import java.util.HashSet;
33
34 /**
35 * This is a class loader which can load the same classes as another class loader.
36 * <p>
37 * This is mainly useful for tests when you want to load a class, but do it with a class
38 * loader you can dispose. The clone loader just asks the loader to be cloned to get
39 * the bytecodes, but defines the class itself.
40 * <p>
41 * Additionally you can specify a set of classes the loader should not be able to load.
42 */
43 public class IAE_Loader2 extends SecureClassLoader {
44
45 /**
46 * The class loaded to clone.
47 */
48 private final ClassLoader toClone;
49
50 /**
51 * The strings we cannot load.
52 */
53 private final HashSet<String> notLoadable;
54
55 /**
56 * The strings we just delegate.
57 */
58 private final HashSet<String> simpleDelegate;
59
60 /**
61 * Creates a class loader which can load the same classes as the loader which
62 * loaded the <code>IAE_Loader2</code> class itself.
63 * <p>
64 * Only the classes which are loadable by the 'parent' loader are delegated to that
65 * loader (to make it possible mix classes).
66 *
67 * @param name the name of the class loader.
68 * @param parent the parent loader which is first asked to load a class.
69 * @param toClone the class loader to mimic. The clone class loader will be able to
70 * load the same classes as the 'toClone' loader.
71 * @param notLoadable The classes we should not be able to load via this loader.
72 * @param simpleDelegate The names of the classes for which we simply delegate.
73 */
74 public IAE_Loader2(String name, ClassLoader parent, ClassLoader toClone, String[] notLoadable,
75 String[] simpleDelegate) {
76 super(name, parent);
77
78 this.toClone = toClone;
79 this.notLoadable = new HashSet<>(Arrays.asList(notLoadable));
80 this.simpleDelegate = new HashSet<>(Arrays.asList(simpleDelegate));
81 }
82
83 /**
84 * @see java.lang.ClassLoader#findClass(java.lang.String)
85 */
86 @Override
87 protected Class<?> findClass(String name) throws ClassNotFoundException {
88 if (notLoadable.contains(name)) {
89 throw new ClassNotFoundException("The clone class loader explicitely " +
90 "didn't found the class");
91 }
92
93 if (simpleDelegate.contains(name)) {
94 return toClone.loadClass(name);
95 }
96
97 // We just ask the wrapper class loader to find the resource for us
98 URL res = toClone.getResource(name.replace('.', '/') + ".class");
99
100 if (res == null) {
101 throw new ClassNotFoundException(name);
102 }
103
104 try {
105 InputStream is = res.openStream();
106 byte[] code = readStreamIntoBuffer(is, 8192);
107 is.close();
108 return defineClass(name, code, 0, code.length);
109 } catch (IOException e) {
110 throw new ClassNotFoundException(name, e);
111 }
112 }
113
114 /**
115 * Reads all data of a stream into a byte array. The method allocates as
116 * much memory as necessary to put the whole data into that byte
117 * array. The data is read in chunks of <code>chunkSize</code>
118 * chunks.<br><br>
119 * <b>Implementation Note: </b> The data is read in chunks of
120 * <code>chunkSize</code> bytes. The data is copied to the result
121 * array. The memory consumption at the end of the reading is
122 * <code>2 x [size of resulting array] + chunkSize</code>.
123 *
124 * @param is the stream to read the data from
125 * @param chunkSize the size of the chunks the data should be read in
126 * @return the <b>whole</b> data of the stream read into an byte array
127 * @throws IllegalArgumentException if chunkSize <= 0
128 * @throws NullPointerException if is == null
129 * @throws IOException thrown if the provided stream encounters IO problems
130 */
131 public static byte[] readStreamIntoBuffer(InputStream is, int chunkSize)
132 throws IOException {
133
134 // Check preconditions.
135 if (chunkSize <= 0) {
136 throw new IllegalArgumentException("chunkSize <= 0");
137 }
138 else if (is == null) {
139 throw new NullPointerException("is is null");
140 }
141
142 // Temporary buffer for read operations and result buffer.
143 byte[] tempBuffer = new byte[chunkSize];
144 byte[] buffer = new byte[0];
145
146 int bytesRead = 0; // bytes actual read
147 int oldSize = 0; // size of the resulting buffer
148
149 while ((bytesRead = is.read(tempBuffer)) > 0) {
150
151 // Temporary reference to the buffer for the copy operation.
152 byte[] oldBuffer = buffer;
153
154 // Create a new buffer with the size needed and copy data.
155 buffer = new byte[oldSize + bytesRead];
156 System.arraycopy(oldBuffer, 0, buffer, 0, oldBuffer.length);
157
158 // Copy the new data.
159 System.arraycopy(tempBuffer, 0, buffer, oldSize, bytesRead);
160 oldSize += bytesRead;
161 }
162
163 return buffer;
164 }
165 }