mirror of
https://github.com/berkeleydb/libdb.git
synced 2024-11-17 09:36:24 +00:00
165 lines
6.6 KiB
HTML
165 lines
6.6 KiB
HTML
|
<?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 Collections with Entity 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="Entity.html" title="Chapter 4. Using Entity Classes" />
|
|||
|
|
<link rel="prev" href="creatingentitybindings.html" title="Creating Entity Bindings" />
|
|||
|
|
<link rel="next" href="entitieswithcollections.html" title="Using Entities with Collections" />
|
|||
|
|
</head>
|
|||
|
|
<body>
|
|||
|
|
<div xmlns="" class="navheader">
|
|||
|
|
<div class="libver">
|
|||
|
|
<p>Library Version 11.2.5.2</p>
|
|||
|
|
</div>
|
|||
|
|
<table width="100%" summary="Navigation header">
|
|||
|
|
<tr>
|
|||
|
|
<th colspan="3" align="center">
|
|||
|
|
Creating Collections with Entity Bindings
|
|||
|
|
</th>
|
|||
|
|
</tr>
|
|||
|
|
<tr>
|
|||
|
|
<td width="20%" align="left"><a accesskey="p" href="creatingentitybindings.html">Prev</a> </td>
|
|||
|
|
<th width="60%" align="center">Chapter 4.
|
|||
|
|
Using Entity Classes
|
|||
|
|
</th>
|
|||
|
|
<td width="20%" align="right"> <a accesskey="n" href="entitieswithcollections.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="collectionswithentities"></a>
|
|||
|
|
Creating Collections with Entity Bindings
|
|||
|
|
</h2>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<p>
|
|||
|
|
Stored map objects are created in this example in the same way
|
|||
|
|
as in prior examples, but using entity bindings in place of value
|
|||
|
|
bindings. All value objects passed and returned to the Java
|
|||
|
|
collections API are then actually entity objects (<code class="classname">Part</code>,
|
|||
|
|
<code class="classname">Supplier</code> and <code class="classname">Shipment</code>). The application no longer
|
|||
|
|
deals directly with plain value objects (<code class="classname">PartData</code>,
|
|||
|
|
<code class="classname">SupplierData</code> and <code class="classname">ShipmentData</code>).
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
Since the <code class="literal">partValueBinding</code>, <code class="literal">supplierValueBinding</code>
|
|||
|
|
and <code class="literal">shipmentValueBinding</code> were defined as entity bindings in
|
|||
|
|
the prior section, there are no source code changes necessary for
|
|||
|
|
creating the stored map objects.
|
|||
|
|
</p>
|
|||
|
|
<a id="entity_sampleviews2"></a>
|
|||
|
|
<pre class="programlisting">public class SampleViews
|
|||
|
|
{
|
|||
|
|
...
|
|||
|
|
public SampleViews(SampleDatabase db)
|
|||
|
|
{
|
|||
|
|
...
|
|||
|
|
partMap =
|
|||
|
|
new StoredMap(db.getPartDatabase(),
|
|||
|
|
partKeyBinding, partValueBinding, true);
|
|||
|
|
supplierMap =
|
|||
|
|
new StoredMap(db.getSupplierDatabase(),
|
|||
|
|
supplierKeyBinding, supplierValueBinding, true);
|
|||
|
|
shipmentMap =
|
|||
|
|
new StoredMap(db.getShipmentDatabase(),
|
|||
|
|
shipmentKeyBinding, shipmentValueBinding, true);
|
|||
|
|
...
|
|||
|
|
} </pre>
|
|||
|
|
<p>
|
|||
|
|
Specifying an
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/bind/EntityBinding.html" target="_top">EntityBinding</a>
|
|||
|
|
|
|||
|
|
will select a different
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/collections/StoredMap.html" target="_top">StoredMap</a>
|
|||
|
|
|
|||
|
|
constructor, but the syntax is the same. In general, an entity
|
|||
|
|
binding may be used anywhere that a value binding is used.
|
|||
|
|
</p>
|
|||
|
|
<p>
|
|||
|
|
The following getter methods are defined for use by other
|
|||
|
|
classes in the example program. Instead of returning the map's
|
|||
|
|
entry set
|
|||
|
|
(<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#entrySet()" target="_top">Map.entrySet</a>),
|
|||
|
|
the map's value set
|
|||
|
|
(<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values</a>)
|
|||
|
|
is returned. The entry set was convenient in prior examples because
|
|||
|
|
it allowed enumerating all key/value pairs in the collection. Since
|
|||
|
|
an entity contains the key and the value, enumerating the value set
|
|||
|
|
can now be used more conveniently for the same purpose.
|
|||
|
|
</p>
|
|||
|
|
<a id="entity_sampleviews3"></a>
|
|||
|
|
<pre class="programlisting"><strong class="userinput"><code>import com.sleepycat.collections.StoredValueSet;</code></strong>
|
|||
|
|
...
|
|||
|
|
public class SampleViews
|
|||
|
|
{
|
|||
|
|
...
|
|||
|
|
<strong class="userinput"><code> public StoredValueSet getPartSet()
|
|||
|
|
{
|
|||
|
|
return (StoredValueSet) partMap.values();
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public StoredValueSet getSupplierSet()
|
|||
|
|
{
|
|||
|
|
return (StoredValueSet) supplierMap.values();
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
public StoredValueSet getShipmentSet()
|
|||
|
|
{
|
|||
|
|
return (StoredValueSet) shipmentMap.values();
|
|||
|
|
}</code></strong>
|
|||
|
|
...
|
|||
|
|
} </pre>
|
|||
|
|
<p>
|
|||
|
|
Notice that the collection returned by the
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/collections/StoredMap.html#values()" target="_top">StoredMap.values</a>
|
|||
|
|
|
|||
|
|
method is actually a
|
|||
|
|
<a class="ulink" href="../../java/com/sleepycat/collections/StoredValueSet.html" target="_top">StoredValueSet</a>
|
|||
|
|
|
|||
|
|
and not just a
|
|||
|
|
<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Collection.html" target="_top">Collection</a>
|
|||
|
|
|
|||
|
|
as defined by the
|
|||
|
|
<a class="ulink" href="http://download.oracle.com/javase/1.5.0/docs/api/java/util/Map.html#values()" target="_top">Map.values</a>
|
|||
|
|
|
|||
|
|
interface. As long as duplicate keys are not allowed, this
|
|||
|
|
collection will behave as a true set and will disallow the addition
|
|||
|
|
of duplicates, etc.
|
|||
|
|
</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="navfooter">
|
|||
|
|
<hr />
|
|||
|
|
<table width="100%" summary="Navigation footer">
|
|||
|
|
<tr>
|
|||
|
|
<td width="40%" align="left"><a accesskey="p" href="creatingentitybindings.html">Prev</a> </td>
|
|||
|
|
<td width="20%" align="center">
|
|||
|
|
<a accesskey="u" href="Entity.html">Up</a>
|
|||
|
|
</td>
|
|||
|
|
<td width="40%" align="right"> <a accesskey="n" href="entitieswithcollections.html">Next</a></td>
|
|||
|
|
</tr>
|
|||
|
|
<tr>
|
|||
|
|
<td width="40%" align="left" valign="top">
|
|||
|
|
Creating Entity Bindings
|
|||
|
|
</td>
|
|||
|
|
<td width="20%" align="center">
|
|||
|
|
<a accesskey="h" href="index.html">Home</a>
|
|||
|
|
</td>
|
|||
|
|
<td width="40%" align="right" valign="top">
|
|||
|
|
Using Entities with Collections
|
|||
|
|
</td>
|
|||
|
|
</tr>
|
|||
|
|
</table>
|
|||
|
|
</div>
|
|||
|
|
</body>
|
|||
|
|
</html>
|