collections/tutorial/tuplekeybindings.html

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		Creating Tuple Key Bindings
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            <h2 class="title" style="clear: both"><a id="tuplekeybindings"></a>
		Creating Tuple Key Bindings
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      <p>
    Serial bindings were used in prior examples as key bindings, and
	keys were stored as serialized objects. In this example, a tuple
	binding is used for each key since keys will be stored as tuples.
	Because keys are no longer stored as serialized objects, the
	<tt class="classname">PartKey</tt>, <tt class="classname">SupplierKey</tt> and <tt class="classname">ShipmentKey</tt> classes
	no longer implement the
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/io/Serializable.html" target="_top">Serializable</a>

	interface (this is the only change to these classes and is not
	shown below).
</p>
      <p>
    For the <tt class="classname">Part</tt> key, <tt class="classname">Supplier</tt> key,
    and <tt class="classname">Shipment</tt> key, the
	<tt class="classname">SampleViews</tt> class was changed in this example to create a
	custom
    <a href="/java/com/sleepycat/bind/tuple/TupleBinding.html" target="_top">TupleBinding</a>

	instead of a
    <a href="/java/com/sleepycat/bind/serial/SerialBinding.html" target="_top">SerialBinding</a>.
	The custom tuple key binding classes are defined further below.
</p>
      <a id="tuple_sampleviews"></a>
      <pre class="programlisting"><b class="userinput"><tt>import com.sleepycat.bind.tuple.TupleBinding;
...</tt></b>
public class SampleViews
{
    ...
    public SampleViews(SampleDatabase db)
    {
        ...
        ClassCatalog catalog = db.getClassCatalog();
<b class="userinput"><tt>        EntryBinding partKeyBinding =
            new PartKeyBinding();
        EntityBinding partDataBinding =
            new PartBinding(catalog, PartData.class);
        EntryBinding supplierKeyBinding =
            new SupplierKeyBinding();
        EntityBinding supplierDataBinding =
            new SupplierBinding(catalog, SupplierData.class);
        EntryBinding shipmentKeyBinding =
            new ShipmentKeyBinding();
        EntityBinding shipmentDataBinding =
            new ShipmentBinding(catalog, ShipmentData.class);
        EntryBinding cityKeyBinding =
            TupleBinding.getPrimitiveBinding(String.class);</tt></b>
        ...
    }
} </pre>
      <p>
    For the City key, however, a custom binding class is not needed
	because the key class is a primitive Java type,
    <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/String.html" target="_top">String</a>.
	For any primitive Java type, a tuple binding may be created using the
	<a href="/java/com/sleepycat/bind/tuple/TupleBinding.html#getPrimitiveBinding(java.lang.Class)" target="_top">TupleBinding.getPrimitiveBinding</a>

    static method.
</p>
      <p>
    The custom key binding classes, <tt class="classname">PartKeyBinding</tt>,
	<tt class="classname">SupplierKeyBinding</tt> and <tt class="classname">ShipmentKeyBinding</tt>, are
	defined by extending the
    <a href="/java/com/sleepycat/bind/tuple/TupleBinding.html" target="_top">TupleBinding</a>

	class. The
    <a href="/java/com/sleepycat/bind/tuple/TupleBinding.html" target="_top">TupleBinding</a>

	abstract class implements the
    <a href="/java/com/sleepycat/bind/EntryBinding.html" target="_top">EntryBinding</a>

	interface, and is used for one-to-one bindings between tuples and
	objects. Each binding class implements two methods for converting
	between tuples and objects. Tuple fields are read using the
	<a href="/java/com/sleepycat/bind/tuple/TupleInput.html" target="_top">TupleInput</a>

	parameter and written using the
    <a href="/java/com/sleepycat/bind/tuple/TupleOutput.html" target="_top">TupleOutput</a>

	parameter.
</p>
      <a id="tuple_partkeybinding"></a>
      <pre class="programlisting"><b class="userinput"><tt>import com.sleepycat.bind.tuple.TupleBinding;
import com.sleepycat.bind.tuple.TupleInput;
import com.sleepycat.bind.tuple.TupleOutput;
...</tt></b>
public class SampleViews
{
...

    <b class="userinput"><tt>private static class PartKeyBinding extends TupleBinding
    {
        private PartKeyBinding()
        {
        }

        public Object entryToObject(TupleInput input)
        {
            String number = input.readString();
            return new PartKey(number);
        }

        public void objectToEntry(Object object, TupleOutput output)
        {
            PartKey key = (PartKey) object;
            output.writeString(key.getNumber());
        }
    }
    ...
    private static class SupplierKeyBinding extends TupleBinding
    {
        private SupplierKeyBinding()
        {
        }

        public Object entryToObject(TupleInput input)
        {
            String number = input.readString();
            return new SupplierKey(number);
        }

        public void objectToEntry(Object object, TupleOutput output)
        {
            SupplierKey key = (SupplierKey) object;
            output.writeString(key.getNumber());
        }
    }
    ...
    private static class ShipmentKeyBinding extends TupleBinding
    {
        private ShipmentKeyBinding()
        {
        }

        public Object entryToObject(TupleInput input)
        {
            String partNumber = input.readString();
            String supplierNumber = input.readString();
            return new ShipmentKey(partNumber, supplierNumber);
        }

        public void objectToEntry(Object object, TupleOutput output)
        {
            ShipmentKey key = (ShipmentKey) object;
            output.writeString(key.getPartNumber());
            output.writeString(key.getSupplierNumber());
        }
    }</tt></b>
    ...
} </pre>
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