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1   /**
2    * Copyright (C) cedarsoft GmbH.
3    *
4    * Licensed under the GNU General Public License version 3 (the "License")
5    * with Classpath Exception; you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at
7    *
8    *         http://www.cedarsoft.org/gpl3ce
9    *         (GPL 3 with Classpath Exception)
10   *
11   * This code is free software; you can redistribute it and/or modify it
12   * under the terms of the GNU General Public License version 3 only, as
13   * published by the Free Software Foundation. cedarsoft GmbH designates this
14   * particular file as subject to the "Classpath" exception as provided
15   * by cedarsoft GmbH in the LICENSE file that accompanied this code.
16   *
17   * This code is distributed in the hope that it will be useful, but WITHOUT
18   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
20   * version 3 for more details (a copy is included in the LICENSE file that
21   * accompanied this code).
22   *
23   * You should have received a copy of the GNU General Public License version
24   * 3 along with this work; if not, write to the Free Software Foundation,
25   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
26   *
27   * Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
28   * or visit www.cedarsoft.com if you need additional information or
29   * have any questions.
30   */
31  
32  package com.cedarsoft.test.io;
33  
34  import com.cedarsoft.UnsupportedVersionException;
35  import com.cedarsoft.Version;
36  import com.cedarsoft.VersionRange;
37  import com.cedarsoft.serialization.stax.AbstractStaxMateSerializer;
38  import com.cedarsoft.test.Money;
39  import org.codehaus.staxmate.out.SMOutputElement;
40  
41  import javax.xml.stream.XMLStreamException;
42  import javax.xml.stream.XMLStreamReader;
43  import java.io.IOException;
44  
45  /**
46   * This is an extended version of money serializer.
47   * <p/>
48   * It represents the next step of the evolution of MoneySerializer.
49   * This is an example for a refactoring that might happen, after the serializer has been
50   * released (and shipped to thousands of customers creating millions of files).
51   * <p/>
52   * Therefore this serializer is able to still read the old format.
53   * Writing is only supported for the latest file.
54   */
55  public class MoneySerializer2 extends AbstractStaxMateSerializer<Money> {
56    public MoneySerializer2() {
57      //This serializer supports an old version, too
58      super( "money", "http://thecompany.com/test/money", new VersionRange( new Version( 1, 0, 0 ), new Version( 1, 0, 1 ) ) );
59    }
60  
61    @Override
62    public void serialize( SMOutputElement serializeTo, Money object ) throws IOException, XMLStreamException {
63      serializeTo.addAttribute( "cents", String.valueOf( object.getCents() ) );
64      //We use an attribute - just because it is possible...
65    }
66  
67  
68    @Override
69    public Money deserialize( XMLStreamReader deserializeFrom, Version formatVersion ) throws IOException, XMLStreamException {
70      //This serializer supports reading of an old format. Therefore we have to switch based on the format version.
71      //This might be solved using the strategy pattern. But in most of the cases the format changes only in small portions.
72      //So it seems easier to add just one if/else.
73      //If a serializer evolves further a switch to the strategy pattern might be done. A simple map holding the strategies should do it.
74  
75  
76      //The common case - current version
77      if ( formatVersion.equals( new Version( 1, 0, 1 ) ) ) {
78        int cents = Integer.parseInt( deserializeFrom.getAttributeValue( null, "cents" ) );
79  
80        //We have to close the tag! Every stax based serializer has to close its tag
81        //getText does this automatically for us. But when only using attributes, we have to close it manually.
82        closeTag( deserializeFrom );
83  
84        return new Money( cents );
85  
86        //The old format that does not use an attribute but text instead
87      } else if ( formatVersion.equals( new Version( 1, 0, 0 ) ) ) {
88        int cents = Integer.parseInt( getText( deserializeFrom ) );
89  
90        //We don't have to close the tag. The getText method does that for us
91        return new Money( cents );
92  
93        //Whoo - something went terribly wrong
94      } else {
95        throw new UnsupportedVersionException( formatVersion, getFormatVersionRange() );
96      }
97    }
98  }