1 /* CombinedClassLoader.java -- Multiple class loader support for proxy.
2    Copyright (C) 2006 Free Software Foundation, Inc.
3 
4 This file is part of GNU Classpath.
5 
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
9 any later version.
10 
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 General Public License for more details.
15 
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING.  If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301 USA.
20 
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library.  Thus, the terms and
23 conditions of the GNU General Public License cover the whole
24 combination.
25 
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module.  An independent module is a module which is not derived from
33 or based on this library.  If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so.  If you do not wish to do so, delete this
36 exception statement from your version. */
37 
38 
39 package gnu.java.rmi.server;
40 
41 import java.io.IOException;
42 import java.net.URL;
43 import java.util.Collection;
44 import java.util.Enumeration;
45 import java.util.Iterator;
46 import java.util.ArrayList;
47 
48 /**
49  * This class supports the multiple class loaders to load the resources. It is
50  * used for constructing proxy classes that implement interfaces, loaded by
51  * the several different class loaders.
52  *
53  * @author Audrius Meskauskas (AudriusA@Bioinformatics.org)
54  */
55 public class CombinedClassLoader extends ClassLoader
56 {
57   /**
58    * The class loader array.
59    */
60   ClassLoader[] loaders;
61 
62   /**
63    * Create a new combined class loader that uses the given collection of
64    * loaders to load the classes and resources. The loader order is equal to
65    * the order, returned by the collection interator. The duplicate loaders
66    * are discarded and the system class loader is added as the last loader.
67    *
68    * @param a_loaders the loadery collection (may contain duplicate instances
69    * that will be discarded.
70    */
CombinedClassLoader(Collection a_loaders)71   public CombinedClassLoader(Collection a_loaders)
72   {
73     ArrayList sLoaders = new ArrayList(a_loaders.size());
74 
75     Iterator iter = a_loaders.iterator();
76     Object cl;
77     while (iter.hasNext())
78       {
79         cl = iter.next();
80         if (cl!=null && !sLoaders.contains(cl))
81           sLoaders.add(cl);
82       }
83 
84     loaders = new ClassLoader[sLoaders.size()];
85 
86     for (int i = 0; i < loaders.length; i++)
87       loaders[i] = (ClassLoader) sLoaders.get(i);
88   }
89 
90   /**
91    * Find the class with the given name.
92    */
findClass(String name)93   protected Class findClass(String name) throws ClassNotFoundException
94   {
95     for (int i = 0; i < loaders.length; i++)
96       {
97         try
98           {
99             return loaders[i].loadClass(name);
100           }
101         catch (ClassNotFoundException e)
102           {
103             // try another.
104           }
105       }
106     return super.findClass(name);
107   }
108 
109   /**
110    * Find resource with the given name.
111    */
findResource(String name)112   protected URL findResource(String name)
113   {
114     for (int i = 0; i < loaders.length; i++)
115       {
116         URL resource = loaders[i].getResource(name);
117         if (resource != null)
118           return resource;
119       }
120     return super.findResource(name);
121   }
122 
123   /**
124    * Find resources with the given name.
125    */
findResources(String name)126   protected Enumeration findResources(String name) throws IOException
127   {
128     for (int i = 0; i < loaders.length; i++)
129       {
130         Enumeration resource = loaders[i].getResources(name);
131         if (resource != null)
132           return resource;
133       }
134     return super.findResources(name);  }
135 }
136