RedefineClassHelper.java revision 2618:f1ca22ebd70f 
1/*
2 * Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
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
24import java.io.PrintWriter;
25import java.lang.instrument.*;
26import jdk.test.lib.compiler.InMemoryJavaCompiler;
27
28/*
29 * Helper class to write tests that redefine classes.
30 * When main method is run, it will create a redefineagent.jar that can be used
31 * with the -javaagent option to support redefining classes in jtreg tests.
32 *
33 * See sample test in test/testlibrary_tests/RedefineClassTest.java
34 */
35public class RedefineClassHelper {
36
37    public static Instrumentation instrumentation;
38    public static void premain(String agentArgs, Instrumentation inst) {
39        instrumentation = inst;
40    }
41
42    /**
43     * Redefine a class
44     *
45     * @param clazz Class to redefine
46     * @param javacode String with the new java code for the class to be redefined
47     */
48    public static void redefineClass(Class clazz, String javacode) throws Exception {
49        byte[] bytecode = InMemoryJavaCompiler.compile(clazz.getName(), javacode);
50        redefineClass(clazz, bytecode);
51    }
52
53    /**
54     * Redefine a class
55     *
56     * @param clazz Class to redefine
57     * @param bytecode byte[] with the new class
58     */
59    public static void redefineClass(Class clazz, byte[] bytecode) throws Exception {
60        instrumentation.redefineClasses(new ClassDefinition(clazz, bytecode));
61    }
62
63    /**
64     * Main method to be invoked before test to create the redefineagent.jar
65     */
66    public static void main(String[] args) throws Exception {
67        ClassFileInstaller.main("RedefineClassHelper");
68
69        PrintWriter pw = new PrintWriter("MANIFEST.MF");
70        pw.println("Premain-Class: RedefineClassHelper");
71        pw.println("Can-Redefine-Classes: true");
72        pw.close();
73
74        sun.tools.jar.Main jarTool = new sun.tools.jar.Main(System.out, System.err, "jar");
75        if (!jarTool.run(new String[] { "-cmf", "MANIFEST.MF", "redefineagent.jar", "RedefineClassHelper.class" })) {
76            throw new Exception("jar operation failed");
77        }
78    }
79}
80