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<title>Berkeley DB Reference Guide: Tuple - Creating tuple-serial entity bindings</title>
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<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Java API Tutorial - Tuple</dl></h3></td>
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<p>
<h3 align=center>Tuple - Creating tuple-serial entity bindings</h3>
<p>In the prior example serial keys and serial values were used, and the
<a href="../../java/com/sleepycat/bdb/bind/serial/SerialSerialBinding.html">SerialSerialBinding</a>
 base class was
used for entity bindings.  In this example, tuple keys and serial values are
used and therefore the 
<a href="../../java/com/sleepycat/bdb/bind/serial/TupleSerialBinding.html">TupleSerialBinding</a>
 base class is used for entity bindings.</p>
<p>As with any entity binding, a key and value is converted to an entity in
the 
<a href="../../java/com/sleepycat/bdb/bind/serial/TupleSerialBinding.html#dataToObject">TupleSerialBinding.dataToObject</a>
method, and from an entity to a key and value in the
<a href="../../java/com/sleepycat/bdb/bind/serial/TupleSerialBinding.html#objectToKey">TupleSerialBinding.objectToKey</a>
 and
<a href="../../java/com/sleepycat/bdb/bind/serial/TupleSerialBinding.html#objectToValue">TupleSerialBinding.objectToValue</a>
methods.  But since keys are stored as tuples, not as serialized objects, key
fields are read and written using the 
<a href="../../java/com/sleepycat/bdb/bind/tuple/TupleInput.html">TupleInput</a>
 and 
<a href="../../java/com/sleepycat/bdb/bind/tuple/TupleOutput.html">TupleOutput</a>
parameters.</p>
<hr size=1 noshade>
<p>The <b>SampleViews</b> class contains the modified entity binding
classes that were defined in the prior example: <b>PartBinding</b>,
<b>SupplierBinding</b> and <b>ShipmentBinding</b>.</p>
<blockquote><pre>
<b>
import com.sleepycat.bdb.bind.serial.TupleSerialBinding;
import com.sleepycat.bdb.bind.tuple.TupleFormat;
import com.sleepycat.bdb.bind.tuple.TupleInput;
import com.sleepycat.bdb.bind.tuple.TupleOutput;
...
</b>public class SampleViews
{
    ...
    private static class PartBinding extends <b>TupleSerialBinding</b>
    {
        private PartBinding(<b>TupleFormat</b> keyFormat,
                            SerialFormat valueFormat)
        {
            super(keyFormat, valueFormat);
        }
<p>
        public Object dataToObject(<b>TupleInput</b> keyInput, Object valueInput)
            throws IOException
        {
<b>            String number = keyInput.readString();
</b>            PartValue value = (PartValue) valueInput;
            return new Part(<b>number</b>, value.getName(), value.getColor(),
                            value.getWeight(), value.getCity());
        }
<p>
        public void objectToKey(Object object, <b>TupleOutput</b> output)
            throws IOException
        {
            Part part = (Part) object;
<b>            output.writeString(part.getNumber());
</b>        }
<p>
        public Object objectToValue(Object object)
            throws IOException
        {
            Part part = (Part) object;
            return new PartValue(part.getName(), part.getColor(),
                                 part.getWeight(), part.getCity());
        }
    }
<p>
    private static class SupplierBinding extends <b>TupleSerialBinding</b>
    {
        private SupplierBinding(<b>TupleFormat</b> keyFormat,
                                SerialFormat valueFormat)
        {
            super(keyFormat, valueFormat);
        }
<p>
        public Object dataToObject(<b>TupleInput</b> keyInput, Object valueInput)
            throws IOException
        {
<b>            String number = keyInput.readString();
</b>            SupplierValue value = (SupplierValue) valueInput;
            return new Supplier(<b>number</b>, value.getName(),
                                value.getStatus(), value.getCity());
        }
<p>
        public void objectToKey(Object object, <b>TupleOutput</b> output)
            throws IOException
        {
            Supplier supplier = (Supplier) object;
<b>            output.writeString(supplier.getNumber());
</b>        }
<p>
        public Object objectToValue(Object object)
            throws IOException
        {
            Supplier supplier = (Supplier) object;
            return new SupplierValue(supplier.getName(), supplier.getStatus(),
                                     supplier.getCity());
        }
    }
<p>
    private static class ShipmentBinding extends <b>TupleSerialBinding</b>
    {
        private ShipmentBinding(<b>TupleFormat</b> keyFormat,
                                SerialFormat valueFormat)
        {
            super(keyFormat, valueFormat);
        }
<p>
        public Object dataToObject(<b>TupleInput</b> keyInput, Object valueInput)
            throws IOException
        {
<b>            String partNumber = keyInput.readString();
            String supplierNumber = keyInput.readString();
</b>            ShipmentValue value = (ShipmentValue) valueInput;
            return new Shipment(<b>partNumber</b>, <b>supplierNumber</b>,
                                value.getQuantity());
        }
<p>
        public void objectToKey(Object object, <b>TupleOutput</b> output)
            throws IOException
        {
            Shipment shipment = (Shipment) object;
<b>            output.writeString(shipment.getPartNumber());
            output.writeString(shipment.getSupplierNumber());
</b>        }
<p>
        public Object objectToValue(Object object)
            throws IOException
        {
            Shipment shipment = (Shipment) object;
            return new ShipmentValue(shipment.getQuantity());
        }
    }
}
</pre></blockquote>
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