Source for gnu.java.net.loader.URLStreamHandlerCache

   1: /* URLStreamHandlerCache.java -- a cache for URLStreamHandlers
   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.net.loader;
  40: 
  41: import java.net.URLStreamHandler;
  42: import java.net.URLStreamHandlerFactory;
  43: import java.util.HashMap;
  44: 
  45: /**
  46:  */
  47: public class URLStreamHandlerCache
  48: {
  49:   /**
  50:    * A cache to store mappings between handler factory and its
  51:    * private protocol handler cache (also a HashMap), so we can avoid
  52:    * creating handlers each time the same protocol comes.
  53:    */
  54:   private HashMap<URLStreamHandlerFactory, HashMap<String, URLStreamHandler>> factoryCache
  55:     = new HashMap<URLStreamHandlerFactory, HashMap<String, URLStreamHandler>>(5);
  56: 
  57:   public URLStreamHandlerCache()
  58:   {
  59:   }
  60: 
  61:   public synchronized void add(URLStreamHandlerFactory factory)
  62:   {
  63:     // Since we only support three protocols so far, 5 is enough
  64:     // for cache initial size.
  65:     if (factory != null && factoryCache.get(factory) == null)
  66:       factoryCache.put(factory, new HashMap<String, URLStreamHandler>(5));
  67:   }
  68: 
  69:   public synchronized URLStreamHandler get(URLStreamHandlerFactory factory,
  70:                                            String protocol)
  71:   {
  72:     if (factory == null)
  73:       return null;
  74:     // Check if there're handler for the same protocol in cache.
  75:     HashMap<String, URLStreamHandler> cache = factoryCache.get(factory);
  76:     URLStreamHandler handler = cache.get(protocol);
  77:     if (handler == null)
  78:       {
  79:         // Add it to cache.
  80:         handler = factory.createURLStreamHandler(protocol);
  81:         cache.put(protocol, handler);
  82:       }
  83:     return handler;
  84:   }
  85: }