KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > hsqldb > types > JavaObject


1 /* Copyright (c) 2001-2005, The HSQL Development Group
2  * All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are met:
6  *
7  * Redistributions of source code must retain the above copyright notice, this
8  * list of conditions and the following disclaimer.
9  *
10  * Redistributions in binary form must reproduce the above copyright notice,
11  * this list of conditions and the following disclaimer in the documentation
12  * and/or other materials provided with the distribution.
13  *
14  * Neither the name of the HSQL Development Group nor the names of its
15  * contributors may be used to endorse or promote products derived from this
16  * software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
22  * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
26  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30
31
32 package org.hsqldb.types;
33
34 import java.io.Serializable JavaDoc;
35
36 import org.hsqldb.HsqlException;
37 import org.hsqldb.Trace;
38 import org.hsqldb.lib.InOutUtil;
39
40 /**
41  * Represents of an instance of an OTHER field value. <p>
42  *
43  * Prior to 1.7.0 there were problems storing Objects of normal column types
44  * in columns of the type OTHER. In 1.7.0 changes were made to allow this,
45  * but as all the conversion took place inside the engine, it introduced a
46  * requirement for all classes for objects stored in OTHER columns to be
47  * available on the runtime class path of the engine. <p>
48  *
49  * In 1.7.2, the introduction of real preprared statement support allows us
50  * revert to the pre 1.7.0 behaviour without the artificial limitations. <p>
51  *
52  * The classes for stored objects need not be available to open and operate
53  * the database in general. The classes need to be available only if a
54  * conversion from one of these objects to another type is performed inside
55  * the engine while operating the database.
56  *
57  * The current limitation is that in SQL statements, values of type String
58  * (CHARACTER and related SQL types) cannot be stored in columns of type
59  * OTHER. This limitation does not exist for String values assigned to
60  * PreparedStatement variables.
61  *
62  * @author fredt@users
63  * @version 1.7.2
64  * @since 1.7.2
65  */
66 public class JavaObject {
67
68     private byte[] data;
69
70     /**
71      * Constructor used inside the engine when an already serialized
72      * Object is read from a file (.log, .script, .data or text table source).
73      */
74     public JavaObject(byte[] data) {
75         this.data = data;
76     }
77
78     /**
79      * Constructor used inside the engine to convert an Object into an
80      * object of type OTHER.
81      * Used also with JDBC setParameter().
82      * If parameter serialize is true, the Object is serialized for storage.
83      */
84     public JavaObject(Serializable JavaDoc o) throws HsqlException {
85
86         try {
87             data = InOutUtil.serialize(o);
88         } catch (Exception JavaDoc e) {
89             throw Trace.error(Trace.SERIALIZATION_FAILURE, e.getMessage());
90         }
91     }
92
93     public byte[] getBytes() {
94         return data;
95     }
96
97     public int getBytesLength() {
98         return data.length;
99     }
100
101     /**
102      * This method is called from classes implementing the JDBC
103      * interfaces. Inside the engine it is used for conversion from a value of
104      * type OTHER to another type. It will throw if the OTHER is an instance
105      * of a classe that is not available.
106      */
107     public Serializable JavaDoc getObject() throws HsqlException {
108
109         try {
110             return InOutUtil.deserialize(data);
111         } catch (Exception JavaDoc e) {
112             throw Trace.error(Trace.SERIALIZATION_FAILURE, e.getMessage());
113         }
114     }
115
116     /**
117      * Returns String repsentation of this object.
118      *
119      * @return a String represntation of this object.
120      */
121     public String JavaDoc toString() {
122         return super.toString();
123     }
124 }
125
Popular Tags