blob: 8d1c21be5c6cfb475f061e7d45e86e1b2cc0f219 (
plain)
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
220
221
222
223
224
225
226
|
<?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>Placing Objects in an Entity Store</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="Getting Started with Berkeley DB" />
<link rel="up" href="persist_access.html" title="Chapter 5. Saving and Retrieving Objects" />
<link rel="prev" href="simpleda.html" title="SimpleDA.class" />
<link rel="next" href="simpleget.html" title="Retrieving Objects from an Entity Store" />
</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">Placing Objects in an Entity Store</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="simpleda.html">Prev</a> </td>
<th width="60%" align="center">Chapter 5. Saving and Retrieving Objects</th>
<td width="20%" align="right"> <a accesskey="n" href="simpleget.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="simpleput"></a>Placing Objects in an Entity Store</h2>
</div>
</div>
</div>
<p>
In order to place an object in a DPL entity store,
you must:
</p>
<div class="orderedlist">
<ol type="1">
<li>
<p>
Open the environment and store.
</p>
</li>
<li>
<p>
Instantiate the object.
</p>
</li>
<li>
<p>
Put the object to the store using the
<code class="methodname">put()</code> method
for the object's primary index.
</p>
</li>
</ol>
</div>
<p>
The following example uses the <code class="classname">SimpleDA</code>
class that we show in <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a> to put a
<code class="classname">SimpleEntityClass</code> object (see
<a class="xref" href="persist_access.html#simpleentity" title="A Simple Entity Class">A Simple Entity Class</a>) to the
entity store.
</p>
<p>
To begin, we import the Java classes that our example
needs. We also instantiate the private data members that we
require.
</p>
<pre class="programlisting">package persist.gettingStarted;
import java.io.File;
import java.io.FileNotFoundException;
import com.sleepycat.db.DatabaseException;
import com.sleepycat.db.Environment;
import com.sleepycat.db.EnvironmentConfig;
import com.sleepycat.persist.EntityStore;
import com.sleepycat.persist.StoreConfig;
public class SimpleStorePut {
private static File envHome = new File("./JEDB");
private Environment envmnt;
private EntityStore store;
private SimpleDA sda; </pre>
<p>
Next we create a method that simply opens our database
environment and entity store for us.
</p>
<pre class="programlisting"> // The setup() method opens the environment and store
// for us.
public void setup()
throws DatabaseException {
EnvironmentConfig envConfig = new EnvironmentConfig();
StoreConfig storeConfig = new StoreConfig();
envConfig.setAllowCreate(true);
storeConfig.setAllowCreate(true);
try {
// Open the environment and entity store
envmnt = new Environment(envHome, envConfig);
store = new EntityStore(envmnt, "EntityStore", storeConfig);
} catch (FileNotFoundException fnfe) {
System.err.println("setup(): " + fnfe.toString());
System.exit(-1);
}
} </pre>
<p>
We also need a method to close our environment and store.
</p>
<pre class="programlisting"> // Close our environment and store.
public void shutdown()
throws DatabaseException {
store.close();
envmnt.close();
} </pre>
<p>
Now we need to create a method to actually write objects to our
store. This method creates a <code class="classname">SimpleDA</code>
object (see <a class="xref" href="simpleda.html" title="SimpleDA.class">SimpleDA.class</a> that we
will use to access our indexes. Then we instantiate a series
of <code class="classname">SimpleEntityClass</code> (see <a class="xref" href="persist_access.html#simpleentity" title="A Simple Entity Class">A Simple Entity Class</a>)
objects that we
will place in our store. Finally, we use our primary index
(obtained from the <code class="classname">SimpleDA</code> class
instance) to actually place these objects in our store.
</p>
<p>
In <a class="xref" href="simpleget.html" title="Retrieving Objects from an Entity Store">Retrieving Objects from an Entity Store</a>
we show a class that is used to retrieve these objects.
</p>
<pre class="programlisting"> // Populate the entity store
private void run()
throws DatabaseException {
setup();
// Open the data accessor. This is used to store
// persistent objects.
sda = new SimpleDA(store);
// Instantiate and store some entity classes
SimpleEntityClass sec1 = new SimpleEntityClass();
SimpleEntityClass sec2 = new SimpleEntityClass();
SimpleEntityClass sec3 = new SimpleEntityClass();
SimpleEntityClass sec4 = new SimpleEntityClass();
SimpleEntityClass sec5 = new SimpleEntityClass();
sec1.setPKey("keyone");
sec1.setSKey("skeyone");
sec2.setPKey("keytwo");
sec2.setSKey("skeyone");
sec3.setPKey("keythree");
sec3.setSKey("skeytwo");
sec4.setPKey("keyfour");
sec4.setSKey("skeythree");
sec5.setPKey("keyfive");
sec5.setSKey("skeyfour");
sda.pIdx.put(sec1);
sda.pIdx.put(sec2);
sda.pIdx.put(sec3);
sda.pIdx.put(sec4);
sda.pIdx.put(sec5);
shutdown();
} </pre>
<p>
Finally, to complete our class, we need a
<code class="methodname">main()</code> method, which simply calls our
<code class="methodname">run()</code> method.
</p>
<pre class="programlisting"> // main
public static void main(String args[]) {
SimpleStorePut ssp = new SimpleStorePut();
try {
ssp.run();
} catch (DatabaseException dbe) {
System.err.println("SimpleStorePut: " + dbe.toString());
dbe.printStackTrace();
} catch (Exception e) {
System.out.println("Exception: " + e.toString());
e.printStackTrace();
}
System.out.println("All done.");
}
} </pre>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="simpleda.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="persist_access.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="simpleget.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">SimpleDA.class </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> Retrieving Objects from an Entity Store</td>
</tr>
</table>
</div>
</body>
</html>
|
