ClassPathLoader.java revision 608:7e06bf1dcb09 
1/*
2 * Copyright (c) 2000, 2004, 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25package sun.rmi.rmic.iiop;
26
27import java.io.*;
28import sun.tools.java.ClassPath ;
29import sun.tools.java.ClassFile ;
30
31/**
32 * A ClassLoader that will ultimately use a given sun.tools.java.ClassPath to
33 * find the desired file.  This works for any JAR files specified in the given
34 * ClassPath as well -- reusing all of that wonderful sun.tools.java code.
35 *
36 *@author Everett Anderson
37 */
38public class ClassPathLoader extends ClassLoader
39{
40    private ClassPath classPath;
41
42    public ClassPathLoader(ClassPath classPath) {
43        this.classPath = classPath;
44    }
45
46    // Called by the super class
47    protected Class findClass(String name) throws ClassNotFoundException
48    {
49        byte[] b = loadClassData(name);
50        return defineClass(name, b, 0, b.length);
51    }
52
53    /**
54     * Load the class with the given fully qualified name from the ClassPath.
55     */
56    private byte[] loadClassData(String className)
57        throws ClassNotFoundException
58    {
59        // Build the file name and subdirectory from the
60        // class name
61        String filename = className.replace('.', File.separatorChar)
62                          + ".class";
63
64        // Have ClassPath find the file for us, and wrap it in a
65        // ClassFile.  Note:  This is where it looks inside jar files that
66        // are specified in the path.
67        ClassFile classFile = classPath.getFile(filename);
68
69        if (classFile != null) {
70
71            // Provide the most specific reason for failure in addition
72            // to ClassNotFound
73            Exception reportedError = null;
74            byte data[] = null;
75
76            try {
77                // ClassFile is beautiful because it shields us from
78                // knowing if it's a separate file or an entry in a
79                // jar file.
80                DataInputStream input
81                    = new DataInputStream(classFile.getInputStream());
82
83                // Can't rely on input available() since it will be
84                // something unusual if it's a jar file!  May need
85                // to worry about a possible problem if someone
86                // makes a jar file entry with a size greater than
87                // max int.
88                data = new byte[(int)classFile.length()];
89
90                try {
91                    input.readFully(data);
92                } catch (IOException ex) {
93                    // Something actually went wrong reading the file.  This
94                    // is a real error so save it to report it.
95                    data = null;
96                    reportedError = ex;
97                } finally {
98                    // Just don't care if there's an exception on close!
99                    // I hate that close can throw an IOException!
100                    try { input.close(); } catch (IOException ex) {}
101                }
102            } catch (IOException ex) {
103                // Couldn't get the input stream for the file.  This is
104                // probably also a real error.
105                reportedError = ex;
106            }
107
108            if (data == null)
109                throw new ClassNotFoundException(className, reportedError);
110
111            return data;
112        }
113
114        // Couldn't find the file in the class path.
115        throw new ClassNotFoundException(className);
116    }
117}
118