Source for gnu.java.rmi.server.CombinedClassLoader

   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:    */
  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:    */
  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:    */
 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:    */
 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: }