Source for gnu.java.beans.encoder.PrimitivePersistenceDelegate

   1: /* PrimitivePersistenceDelegate.java
   2:  -- A PersistenceDelegate for primitive data types.
   3:    Copyright (C) 2005 Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11: 
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: package gnu.java.beans.encoder;
  40: 
  41: import java.beans.Encoder;
  42: import java.beans.Expression;
  43: import java.beans.PersistenceDelegate;
  44: 
  45: /**
  46:  * A shared PersistenceDelegate implementation for all primitive types.
  47:  *
  48:  * @author Robert Schuster (robertschuster@fsfe.org)
  49:  */
  50: public class PrimitivePersistenceDelegate extends PersistenceDelegate
  51: {
  52: 
  53:   protected Expression instantiate(Object oldInstance, Encoder out)
  54:   {
  55:     // The implementation relies on the fact that every primitive
  56:     // wrapper class has a constructor accepting a String argument.
  57:     // By using these constructors creating a primitive instance
  58:     // depends on the String class only.
  59:     return new Expression(oldInstance, oldInstance.getClass(), "new",
  60:                           new Object[] { oldInstance.toString() });
  61:   }
  62: 
  63:   protected void initialize(Class type, Object oldInstance, Object newInstance, Encoder out)
  64:   {
  65:     // This is a hack to make serializing primitive arrays work correctly.
  66:     // Instead of modifying an existing primitive instance to make it equal
  67:     // with another instance (which is not possible because primitives are
  68:     // immutable) we create a new instance. This is against the specification
  69:     // of the initialize method but make things work fine.
  70:     out.writeExpression(new Expression(oldInstance, oldInstance.getClass(), "new",
  71:                           new Object[] { oldInstance.toString() }));
  72:   }
  73: 
  74: }