mirror of
https://github.com/yasuhirokimura/db18
synced 2026-06-08 18:29:23 +00:00
Yasuhiro KIMURA
132 lines
5.0 KiB
HTML
132 lines
5.0 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Removing the Redundant Value Classes</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB Collections Tutorial" />
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<link rel="up" href="SerializableEntity.html" title="Chapter 6. Using Serializable Entities" />
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<link rel="prev" href="transientfieldsinbinding.html" title="Using Transient Fields in an Entity Binding" />
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<link rel="next" href="Summary.html" title="Chapter 7. Summary" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 18.1.40</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">
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Removing the Redundant Value Classes
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="transientfieldsinbinding.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 6.
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Using Serializable Entities
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="Summary.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="removingredundantvalueclasses"></a>
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Removing the Redundant Value Classes
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</h2>
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</div>
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</div>
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</div>
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<p>
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The <code class="classname">PartData</code>, <code class="classname">SupplierData</code> and <code class="classname">ShipmentData</code>
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classes have been removed in this example, and the <code class="classname">Part</code>,
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<code class="classname">Supplier</code> and <code class="classname">Shipment</code> entity classes are used in
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their place.
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</p>
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<p>
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The serial formats are created with the entity classes.
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</p>
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<a id="sentity_sampledatabase"></a>
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<pre class="programlisting">public class SampleDatabase
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{
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...
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public SampleDatabase(String homeDirectory)
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throws DatabaseException, FileNotFoundException
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{
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...
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secConfig.setKeyCreator(new SupplierByCityKeyCreator(javaCatalog,
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<strong class="userinput"><code>Supplier</code></strong>.class));
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...
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secConfig.setKeyCreator(new ShipmentByPartKeyCreator(javaCatalog,
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<strong class="userinput"><code>Shipment</code></strong>.class));
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...
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secConfig.setKeyCreator(new
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ShipmentBySupplierKeyCreator(javaCatalog,
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<strong class="userinput"><code>Shipment</code></strong>.class));
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...
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}
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} </pre>
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<p>
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The index key creator uses the entity class as well.
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</p>
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<a id="sentity_supplierbycitykeycreator"></a>
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<pre class="programlisting">public class SampleDatabase
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{
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...
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private static class SupplierByCityKeyCreator
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extends TupleSerialKeyCreator
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{
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private SupplierByCityKeyCreator(ClassCatalog catalog,
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Class valueClass)
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{
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super(catalog, valueClass);
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}
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public boolean createSecondaryKey(TupleInput primaryKeyInput,
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Object valueInput,
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TupleOutput indexKeyOutput)
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{
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<strong class="userinput"><code>Supplier</code></strong> supplier = (<strong class="userinput"><code>Supplier</code></strong>) valueInput;
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String city = supplier.getCity();
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if (city != null) {
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indexKeyOutput.writeString(supplier.getCity());
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return true;
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} else {
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return false;
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}
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}
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}
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} </pre>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="transientfieldsinbinding.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="SerializableEntity.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="Summary.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">
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Using Transient Fields in an Entity Binding
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</td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Chapter 7.
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Summary
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</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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