<!--$Id: binding.html,v 1.2 2004/03/30 01:22:46 jtownsen Exp $--> <!--Copyright 1997-2003 by Sleepycat Software, Inc.--> <!--All rights reserved.--> <!--See the file LICENSE for redistribution information.--> <html> <head> <title>Berkeley DB Reference Guide: Serializable Entity - Using transient fields in an entity binding</title> <meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> <meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,Java,C,C++"> </head> <body bgcolor=white> <a name="2"><!--meow--></a> <table width="100%"><tr valign=top> <td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Java API Tutorial - Serializable Entity</dl></h3></td> <td align=right><a href="../bdb_sentity/class.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../bdb_sentity/remove.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p> <h3 align=center>Serializable Entity - Using transient fields in an entity binding</h3> <p>The entity bindings from the prior example have been changed in this example to use the entity object both as a value object and an entity object.</p> <p>Before, the <b>dataToObject</b> method combined the deserialized value object with the key fields to create a new entity object. Now, this method uses the deserialized object directly as an entity, and initializes its key using the fields read from the key tuple.</p> <p>Before, the <b>objectToValue</b> method constructed a new value object using information in the entity. Now it simply returns the entity. Nothing needs to be changed in the entity, since the transient key fields won't be serialized.</p> <hr size=1 noshade> <blockquote><pre> public class SampleViews { ... private static class PartBinding extends TupleSerialBinding { private PartBinding(TupleFormat keyFormat, SerialFormat valueFormat) { super(keyFormat, valueFormat); } <p> public Object dataToObject(TupleInput keyInput, Object valueInput) throws IOException { String number = keyInput.readString(); <b> Part part = (Part) valueInput; part.setKey(number); return part; </b> } <p> public void objectToKey(Object object, TupleOutput output) throws IOException { Part part = (Part) object; output.writeString(part.getNumber()); } <p> public Object objectToValue(Object object) throws IOException { <b> return object; </b> } } <p> private static class SupplierBinding extends TupleSerialBinding { private SupplierBinding(TupleFormat keyFormat, SerialFormat valueFormat) { super(keyFormat, valueFormat); } <p> public Object dataToObject(TupleInput keyInput, Object valueInput) throws IOException { String number = keyInput.readString(); <b> Supplier supplier = (Supplier) valueInput; supplier.setKey(number); return supplier; </b> } <p> public void objectToKey(Object object, TupleOutput output) throws IOException { Supplier supplier = (Supplier) object; output.writeString(supplier.getNumber()); } <p> public Object objectToValue(Object object) throws IOException { <b> return object; </b> } } <p> private static class ShipmentBinding extends TupleSerialBinding { private ShipmentBinding(TupleFormat keyFormat, SerialFormat valueFormat) { super(keyFormat, valueFormat); } <p> public Object dataToObject(TupleInput keyInput, Object valueInput) throws IOException { String partNumber = keyInput.readString(); String supplierNumber = keyInput.readString(); <b> Shipment shipment = (Shipment) valueInput; shipment.setKey(partNumber, supplierNumber); return shipment; </b> } <p> public void objectToKey(Object object, TupleOutput output) throws IOException { Shipment shipment = (Shipment) object; output.writeString(shipment.getPartNumber()); output.writeString(shipment.getSupplierNumber()); } <p> public Object objectToValue(Object object) throws IOException { <b> return object; </b> } } } </pre></blockquote> <table width="100%"><tr><td><br></td><td align=right><a href="../bdb_sentity/class.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../bdb_sentity/remove.html"><img src="../../images/next.gif" alt="Next"></a> </td></tr></table> <p><font size=1><a href="../../sleepycat/legal.html">Copyright (c) 1996-2003</a> <a href="http://www.sleepycat.com">Sleepycat Software, Inc.</a> - All rights reserved.</font> </body> </html>