1 package org.apache.bcel.util;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 import java.lang.reflect.*;
58
59 /***
60 * Java interpreter replacement, i.e., wrapper that uses its own ClassLoader
61 * to modify/generate classes as they're requested. You can take this as a template
62 * for your own applications.<br>
63 * Call this wrapper with
64 * <pre>java org.apache.bcel.util.JavaWrapper <real.class.name> [arguments]</pre>
65 * <p>
66 * To use your own class loader you can set the "bcel.classloader" system property
67 * which defaults to "org.apache.bcel.util.ClassLoader", e.g., with
68 * <pre>java org.apache.bcel.util.JavaWrapper -Dbcel.classloader=foo.MyLoader <real.class.name> [arguments]</pre>
69 * </p>
70 *
71 * @version $Id: JavaWrapper.java,v 1.1.1.1 2001/10/29 20:00:30 jvanzyl Exp $
72 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
73 * @see ClassLoader
74 */
75 public class JavaWrapper {
76 private java.lang.ClassLoader loader;
77
78 private static java.lang.ClassLoader getClassLoader() {
79 String s = System.getProperty("bcel.classloader");
80
81 if((s == null) || "".equals(s))
82 s = "org.apache.bcel.util.ClassLoader";
83
84 try {
85 return (java.lang.ClassLoader)Class.forName(s).newInstance();
86 } catch(Exception e) {
87 throw new RuntimeException(e.toString());
88 }
89 }
90
91 public JavaWrapper(java.lang.ClassLoader loader) {
92 this.loader = loader;
93 }
94
95 public JavaWrapper() {
96 this(getClassLoader());
97 }
98
99 /*** Runs the main method of the given class with the arguments passed in argv
100 *
101 * @param class_name the fully qualified class name
102 * @param argv the arguments just as you would pass them directly
103 */
104 public void runMain(String class_name, String[] argv) throws ClassNotFoundException
105 {
106 Class cl = loader.loadClass(class_name);
107 Method method = null;
108
109 try {
110 method = cl.getMethod("main", new Class[] { argv.getClass() });
111
112 /* Method main is sane ?
113 */
114 int m = method.getModifiers();
115 Class r = method.getReturnType();
116
117 if(!(Modifier.isPublic(m) && Modifier.isStatic(m)) ||
118 Modifier.isAbstract(m) || (r != Void.TYPE))
119 throw new NoSuchMethodException();
120 } catch(NoSuchMethodException no) {
121 System.out.println("In class " + class_name +
122 ": public static void main(String[] argv) is not defined");
123 return;
124 }
125
126 try {
127 method.invoke(null, new Object[] { argv });
128 } catch(Exception ex) {
129 ex.printStackTrace();
130 }
131 }
132
133 /*** Default main method used as wrapper, expects the fully qualified class name
134 * of the real class as the first argument.
135 */
136 public static void main(String[] argv) throws Exception {
137 /* Expects class name as first argument, other arguments are by-passed.
138 */
139 if(argv.length == 0) {
140 System.out.println("Missing class name.");
141 return;
142 }
143
144 String class_name = argv[0];
145 String[] new_argv = new String[argv.length - 1];
146 System.arraycopy(argv, 1, new_argv, 0, new_argv.length);
147
148 JavaWrapper wrapper = new JavaWrapper();
149 wrapper.runMain(class_name, new_argv);
150 }
151 }
152
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