TupleSerialMarshalledBinding


1   /*-
2    * See the file LICENSE for redistribution information.
3    *
4    * Copyright (c) 2000,2006 Oracle.  All rights reserved.
5    *
6    * $Id: TupleSerialMarshalledBinding.java,v 1.23 2006/10/30 21:14:08 bostic Exp $
7    */
8   
9   package com.sleepycat.bind.serial;
10  
11  import com.sleepycat.bind.tuple.MarshalledTupleKeyEntity;
12  import com.sleepycat.bind.tuple.TupleInput;
13  import com.sleepycat.bind.tuple.TupleOutput;
14  
15  /**
16   * A concrete <code>TupleSerialBinding</code> that delegates to the
17   * <code>MarshalledTupleKeyEntity</code> interface of the entity class.
18   * 
19   * <p>The {@link MarshalledTupleKeyEntity} interface must be implemented by the
20   * entity class to convert between the key/data entry and entity object.</p>
21   *
22   * <p> The binding is "tricky" in that it uses the entity class for both the
23   * stored data entry and the combined entity object.  To do this, the entity's
24   * key field(s) are transient and are set by the binding after the data object
25   * has been deserialized. This avoids the use of a "data" class completely.
26   * </p>
27   *
28   * @author Mark Hayes
29   * @see MarshalledTupleKeyEntity
30   */
31  public class TupleSerialMarshalledBinding extends TupleSerialBinding {
32  
33      /**
34       * Creates a tuple-serial marshalled binding object.
35       *
36       * @param classCatalog is the catalog to hold shared class information and
37       * for a database should be a {@link StoredClassCatalog}.
38       *
39       * @param baseClass is the base class for serialized objects stored using
40       * this binding -- all objects using this binding must be an instance of
41       * this class.
42       */
43      public TupleSerialMarshalledBinding(ClassCatalog classCatalog,
44                                          Class   baseClass) {
45  
46          this(new SerialBinding(classCatalog, baseClass));
47      }
48  
49      /**
50       * Creates a tuple-serial marshalled binding object.
51       *
52       * @param dataBinding is the binding used for serializing and deserializing
53       * the entity object.
54       */
55      public TupleSerialMarshalledBinding(SerialBinding dataBinding) {
56  
57          super(dataBinding);
58      }
59  
60      // javadoc is inherited
61      public Object   entryToObject(TupleInput tupleInput, Object   javaInput) {
62  
63          /* Creates the entity by combining the stored key and data.
64           * This "tricky" binding returns the stored data as the entity, but
65           * first it sets the transient key fields from the stored key.
66           */
67          MarshalledTupleKeyEntity entity = (MarshalledTupleKeyEntity) javaInput;
68  
69          if (tupleInput != null) { // may be null if not used by key extractor
70              entity.unmarshalPrimaryKey(tupleInput);
71          }
72          return entity;
73      }
74  
75      // javadoc is inherited
76      public void objectToKey(Object   object, TupleOutput output) {
77  
78          /* Creates the stored key from the entity.
79           */
80          MarshalledTupleKeyEntity entity = (MarshalledTupleKeyEntity) object;
81          entity.marshalPrimaryKey(output);
82      }
83  
84      // javadoc is inherited
85      public Object   objectToData(Object   object) {
86  
87          /* Returns the entity as the stored data.  There is nothing to do here
88           * since the entity's key fields are transient.
89           */
90          return object;
91      }
92  }
93
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