Source for gnu.java.security.prng.PRNGFactory

   1: /* PRNGFactory.java --
   2:    Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc.
   3: 
   4: This file is a 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 of the License, or (at
   9: your option) 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; if not, write to the Free Software
  18: Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19: 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.security.prng;
  40: 
  41: import gnu.java.security.Registry;
  42: 
  43: import java.util.Collections;
  44: import java.util.HashSet;
  45: import java.util.Set;
  46: 
  47: /**
  48:  * A Factory to instantiate pseudo random number generators.
  49:  */
  50: public class PRNGFactory
  51:     implements Registry
  52: {
  53:   /** Trivial constructor to enforce <i>Singleton</i> pattern. */
  54:   protected PRNGFactory()
  55:   {
  56:   }
  57: 
  58:   /**
  59:    * Returns an instance of a padding algorithm given its name.
  60:    *
  61:    * @param prng the case-insensitive name of the PRNG.
  62:    * @return an instance of the pseudo-random number generator.
  63:    * @exception InternalError if the implementation does not pass its self-
  64:    *              test.
  65:    */
  66:   public static final IRandom getInstance(String prng)
  67:   {
  68:     if (prng == null)
  69:       return null;
  70: 
  71:     prng = prng.trim();
  72:     IRandom result = null;
  73:     if (prng.equalsIgnoreCase(MD_PRNG))
  74:       result = new MDGenerator();
  75: 
  76:     return result;
  77:   }
  78: 
  79:   /**
  80:    * Returns a {@link Set} of names of padding algorithms supported by this
  81:    * <i>Factory</i>.
  82:    *
  83:    * @return a {@link Set} of pseudo-random number generator algorithm names
  84:    *         (Strings).
  85:    */
  86:   public static final Set getNames()
  87:   {
  88:     HashSet hs = new HashSet();
  89:     hs.add(MD_PRNG);
  90:     return Collections.unmodifiableSet(hs);
  91:   }
  92: }