Source for gnu.CORBA.gnuValueHolder

   1: /* gnuValueHolder.java --
   2:    Copyright (C) 2005 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.CORBA;
  40: 
  41: import gnu.CORBA.CDR.Vio;
  42: 
  43: import org.omg.CORBA.TypeCode;
  44: import org.omg.CORBA.ValueBaseHolder;
  45: import org.omg.CORBA.portable.BoxedValueHelper;
  46: import org.omg.CORBA.portable.InputStream;
  47: import org.omg.CORBA.portable.OutputStream;
  48: 
  49: import java.io.Serializable;
  50: 
  51: /**
  52:  * Boxed value holder that also remembers the value type and the value helper.
  53:  *
  54:  * @author Audrius Meskauskas, Lithuania (AudriusA@Bioinformatics.org)
  55:  */
  56: public class gnuValueHolder
  57:   extends ValueBaseHolder
  58: {
  59:   /**
  60:    * The type code of the stored value.
  61:    */
  62:   TypeCode type;
  63: 
  64:   /**
  65:    * The helper that could read and write fields of the boxed value.
  66:    */
  67:   transient BoxedValueHelper helper;
  68: 
  69:   /**
  70:    * If true, the helper not available.
  71:    */
  72:   transient boolean helper_NA;
  73: 
  74:   /**
  75:    * Create a new instance for the given value and given type.
  76:    */
  77:   public gnuValueHolder(Serializable value, TypeCode a_type)
  78:   {
  79:     super(value);
  80:     type = a_type;
  81:   }
  82: 
  83:   /**
  84:    * Get the true type, as it was passed in the constructor.
  85:    */
  86:   public TypeCode _type()
  87:   {
  88:     return type;
  89:   }
  90: 
  91:   /**
  92:    * Write content to the output stream. Tries to locate the
  93:    * corresponding helper class.
  94:    */
  95:   public void _write(OutputStream output)
  96:   {
  97:     findHelper();
  98:     if (helper == null)
  99:       super._write(output);
 100:     else
 101:       Vio.write(output, value, helper);
 102:   }
 103: 
 104:   /**
 105:    * Read, trying to locate helper, if possible.
 106:    */
 107:   public void _read(InputStream input)
 108:   {
 109:     findHelper();
 110:     if (helper == null)
 111:       super._read(input);
 112:     else
 113:       value = Vio.read(input, helper);
 114:   }
 115: 
 116:   /**
 117:    * Set the read and write methods.
 118:    */
 119:   void findHelper()
 120:   {
 121:     if (helper != null || helper_NA)
 122:       return;
 123:     try
 124:       {
 125:         Class helperClass =
 126:           ObjectCreator.forName(ObjectCreator.toHelperName(type.id()));
 127: 
 128:         helper = (BoxedValueHelper) helperClass.newInstance();
 129:       }
 130:     catch (Exception ex)
 131:       {
 132:         helper_NA = true;
 133:       }
 134:   }
 135: }