1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Creating Tuple Key Bindings</title>
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
<link rel="start" href="index.html" title="Berkeley DB Collections Tutorial" />
<link rel="up" href="Tuple.html" title="Chapter 5. Using Tuples" />
<link rel="prev" href="tupleswithkeycreators.html" title="Using Tuples with Key Creators" />
<link rel="next" href="tuple-serialentitybindings.html" title="Creating Tuple-Serial Entity Bindings" />
</head>
<body>
<div xmlns="" class="navheader">
<div class="libver">
<p>Library Version 12.1.6.1</p>
</div>
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">
Creating Tuple Key Bindings
</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="tupleswithkeycreators.html">Prev</a> </td>
<th width="60%" align="center">Chapter 5.
Using Tuples
</th>
<td width="20%" align="right"> <a accesskey="n" href="tuple-serialentitybindings.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="tuplekeybindings"></a>
Creating Tuple Key Bindings
</h2>
</div>
</div>
</div>
<p>
Serial bindings were used in prior examples as key bindings, and
keys were stored as serialized objects. In this example, a tuple
binding is used for each key since keys will be stored as tuples.
Because keys are no longer stored as serialized objects, the
<code class="classname">PartKey</code>, <code class="classname">SupplierKey</code> and <code class="classname">ShipmentKey</code> classes
no longer implement the
<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/io/Serializable.html" target="_top">Serializable</a>
interface (this is the only change to these classes and is not
shown below).
</p>
<p>
For the <code class="classname">Part</code> key, <code class="classname">Supplier</code> key,
and <code class="classname">Shipment</code> key, the
<code class="classname">SampleViews</code> class was changed in this example to create a
custom
<a class="ulink" href="../../java/com/sleepycat/bind/tuple/TupleBinding.html" target="_top">TupleBinding</a>
instead of a
<a class="ulink" href="../../java/com/sleepycat/bind/serial/SerialBinding.html" target="_top">SerialBinding</a>.
The custom tuple key binding classes are defined further below.
</p>
<a id="tuple_sampleviews"></a>
<pre class="programlisting"><strong class="userinput"><code>import com.sleepycat.bind.tuple.TupleBinding;
...</code></strong>
public class SampleViews
{
...
public SampleViews(SampleDatabase db)
{
...
ClassCatalog catalog = db.getClassCatalog();
<strong class="userinput"><code> EntryBinding partKeyBinding =
new PartKeyBinding();
EntityBinding partDataBinding =
new PartBinding(catalog, PartData.class);
EntryBinding supplierKeyBinding =
new SupplierKeyBinding();
EntityBinding supplierDataBinding =
new SupplierBinding(catalog, SupplierData.class);
EntryBinding shipmentKeyBinding =
new ShipmentKeyBinding();
EntityBinding shipmentDataBinding =
new ShipmentBinding(catalog, ShipmentData.class);
EntryBinding cityKeyBinding =
TupleBinding.getPrimitiveBinding(String.class);</code></strong>
...
}
} </pre>
<p>
For the City key, however, a custom binding class is not needed
because the key class is a primitive Java type,
<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/lang/String.html" target="_top">String</a>.
For any primitive Java type, a tuple binding may be created using the
<a class="ulink" href="../../java/com/sleepycat/bind/tuple/TupleBinding.html#getPrimitiveBinding(java.lang.Class)" target="_top">TupleBinding.getPrimitiveBinding</a>
static method.
</p>
<p>
The custom key binding classes, <code class="classname">PartKeyBinding</code>,
<code class="classname">SupplierKeyBinding</code> and <code class="classname">ShipmentKeyBinding</code>, are
defined by extending the
<a class="ulink" href="../../java/com/sleepycat/bind/tuple/TupleBinding.html" target="_top">TupleBinding</a>
class. The
<a class="ulink" href="../../java/com/sleepycat/bind/tuple/TupleBinding.html" target="_top">TupleBinding</a>
abstract class implements the
<a class="ulink" href="../../java/com/sleepycat/bind/EntryBinding.html" target="_top">EntryBinding</a>
interface, and is used for one-to-one bindings between tuples and
objects. Each binding class implements two methods for converting
between tuples and objects. Tuple fields are read using the
<a class="ulink" href="../../java/com/sleepycat/bind/tuple/TupleInput.html" target="_top">TupleInput</a>
parameter and written using the
<a class="ulink" href="../../java/com/sleepycat/bind/tuple/TupleOutput.html" target="_top">TupleOutput</a>
parameter.
</p>
<a id="tuple_partkeybinding"></a>
<pre class="programlisting"><strong class="userinput"><code>import com.sleepycat.bind.tuple.TupleBinding;
import com.sleepycat.bind.tuple.TupleInput;
import com.sleepycat.bind.tuple.TupleOutput;
...</code></strong>
public class SampleViews
{
...
<strong class="userinput"><code>private static class PartKeyBinding extends TupleBinding
{
private PartKeyBinding()
{
}
public Object entryToObject(TupleInput input)
{
String number = input.readString();
return new PartKey(number);
}
public void objectToEntry(Object object, TupleOutput output)
{
PartKey key = (PartKey) object;
output.writeString(key.getNumber());
}
}
...
private static class SupplierKeyBinding extends TupleBinding
{
private SupplierKeyBinding()
{
}
public Object entryToObject(TupleInput input)
{
String number = input.readString();
return new SupplierKey(number);
}
public void objectToEntry(Object object, TupleOutput output)
{
SupplierKey key = (SupplierKey) object;
output.writeString(key.getNumber());
}
}
...
private static class ShipmentKeyBinding extends TupleBinding
{
private ShipmentKeyBinding()
{
}
public Object entryToObject(TupleInput input)
{
String partNumber = input.readString();
String supplierNumber = input.readString();
return new ShipmentKey(partNumber, supplierNumber);
}
public void objectToEntry(Object object, TupleOutput output)
{
ShipmentKey key = (ShipmentKey) object;
output.writeString(key.getPartNumber());
output.writeString(key.getSupplierNumber());
}
}</code></strong>
...
} </pre>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="tupleswithkeycreators.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="Tuple.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="tuple-serialentitybindings.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">
Using Tuples with Key Creators
</td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top">
Creating Tuple-Serial Entity Bindings
</td>
</tr>
</table>
</div>
</body>
</html>
|
