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Java > Open Source Codes > com > sleepycat > bind > tuple > TupleTupleMarshalledBinding


1 /*-
2  * See the file LICENSE for redistribution information.
3  *
4  * Copyright (c) 2000,2006 Oracle. All rights reserved.
5  *
6  * $Id: TupleTupleMarshalledBinding.java,v 1.22 2006/10/30 21:14:09 bostic Exp $
7  */
8
9 package com.sleepycat.bind.tuple;
10
11 import com.sleepycat.util.RuntimeExceptionWrapper;
12
13 /**
14  * A concrete <code>TupleTupleBinding</code> that delegates to the
15  * <code>MarshalledTupleEntry</code> and
16  * <code>MarshalledTupleKeyEntity</code> interfaces of the entity class.
17  *
18  * <p>This class calls the methods of the {@link MarshalledTupleEntry}
19  * interface to convert between the data entry and entity object. It calls the
20  * methods of the {@link MarshalledTupleKeyEntity} interface to convert between
21  * the key entry and the entity object. These two interfaces must both be
22  * implemented by the entity class.</p>
23  *
24  * @author Mark Hayes
25  */
26 public class TupleTupleMarshalledBinding extends TupleTupleBinding {
27
28     private Class JavaDoc cls;
29
30     /**
31      * Creates a tuple-tuple marshalled binding object.
32      *
33      * <p>The given class is used to instantiate entity objects using
34      * {@link Class#forName}, and therefore must be a public class and have a
35      * public no-arguments constructor. It must also implement the {@link
36      * MarshalledTupleEntry} and {@link MarshalledTupleKeyEntity}
37      * interfaces.</p>
38      *
39      * @param cls is the class of the entity objects.
40      */
41     public TupleTupleMarshalledBinding(Class JavaDoc cls) {
42
43         this.cls = cls;
44
45         // The entity class will be used to instantiate the entity object.
46 //
47 if (!MarshalledTupleKeyEntity.class.isAssignableFrom(cls)) {
48             throw new IllegalArgumentException JavaDoc(cls.toString() +
49                         " does not implement MarshalledTupleKeyEntity");
50         }
51         if (!MarshalledTupleEntry.class.isAssignableFrom(cls)) {
52             throw new IllegalArgumentException JavaDoc(cls.toString() +
53                         " does not implement MarshalledTupleEntry");
54         }
55     }
56
57     // javadoc is inherited
58 public Object JavaDoc entryToObject(TupleInput keyInput, TupleInput dataInput) {
59
60         // This "tricky" binding returns the stored data as the entity, but
61 // first it sets the transient key fields from the stored key.
62 MarshalledTupleEntry obj;
63         try {
64             obj = (MarshalledTupleEntry) cls.newInstance();
65         } catch (IllegalAccessException JavaDoc e) {
66             throw new RuntimeExceptionWrapper(e);
67         } catch (InstantiationException JavaDoc e) {
68             throw new RuntimeExceptionWrapper(e);
69         }
70         if (dataInput != null) { // may be null if used by key extractor
71 obj.unmarshalEntry(dataInput);
72         }
73         MarshalledTupleKeyEntity entity = (MarshalledTupleKeyEntity) obj;
74         if (keyInput != null) { // may be null if used by key extractor
75 entity.unmarshalPrimaryKey(keyInput);
76         }
77         return entity;
78     }
79
80     // javadoc is inherited
81 public void objectToKey(Object JavaDoc object, TupleOutput output) {
82
83         MarshalledTupleKeyEntity entity = (MarshalledTupleKeyEntity) object;
84         entity.marshalPrimaryKey(output);
85     }
86
87     // javadoc is inherited
88 public void objectToData(Object JavaDoc object, TupleOutput output) {
89
90         MarshalledTupleEntry entity = (MarshalledTupleEntry) object;
91         entity.marshalEntry(output);
92     }
93 }
94
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