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<!-- Generated by javadoc on Fri Sep 24 03:23:03 CEST 1999 -->
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Class de.tudarmstadt.ito.xmldbms.helpers.KeyGeneratorImpl
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<pre>
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<a href="packages.html">All Packages</a> <a href="tree.html">Class Hierarchy</a> <a href="Package-de.tudarmstadt.ito.xmldbms.helpers.html">This Package</a> <a href="Package-de.tudarmstadt.ito.xmldbms.helpers.html">Previous</a> <a href="Package-de.tudarmstadt.ito.xmldbms.helpers.html">Next</a> <a href="AllNames.html">Index</a></pre>
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<h1>
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Class de.tudarmstadt.ito.xmldbms.helpers.KeyGeneratorImpl
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</h1>
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<pre>
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java.lang.Object
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+----de.tudarmstadt.ito.xmldbms.helpers.KeyGeneratorImpl
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</pre>
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<dl>
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<dt> public class <b>KeyGeneratorImpl</b>
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<dt> extends Object
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<dt> implements <a href="de.tudarmstadt.ito.xmldbms.KeyGenerator.html#_top_">KeyGenerator</a>
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</dl>
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Default KeyGenerator implementation.
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<P>This key generator assumes that there is a table named XMLDBMSKey
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in the database with an INTEGER column named HighKey. It constructs keys
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from a high key value and a low key value: the high key value forms the
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upper 24 bits of the key and the low key value forms the lower 8 bits of
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the key. The high key value is retrieved from the XMLDBMSKey table, which
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is then incremented by 1. The low key value is initialized to 0 and
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incremented by 1 each time generateKey() is called; when it reaches 255,
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a new high key value is retrieved. Thus, KeyGeneratorImpl can generate
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256 unique key values with a single database access.</P>
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<P>For example, the following code instantiates KeyGeneratorImpl and
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passes it to DOMToDBMS, which uses it to generate keys.</P>
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<PRE>
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// Instantiate KeyGeneratorImpl and initialize it with a Connection.
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KeyGenerator keyGenerator = new KeyGeneratorImpl();
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keyGenerator.initialize(conn);<BR />
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// Pass the key generator to DOMToDBMS.
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domToDBMS = new DOMToDBMS(map, keyGenerator, null);
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</PRE>
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<a name="index"></a>
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<h2>
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<img src="images/constructor-index.gif" width=275 height=38 alt="Constructor Index">
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</h2>
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<dl>
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<dt> <img src="images/yellow-ball-small.gif" width=6 height=6 alt=" o ">
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<a href="#KeyGeneratorImpl(java.sql.Connection)"><b>KeyGeneratorImpl</b></a>(Connection)
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<dd> Construct a new KeyGeneratorImpl object.
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</dl>
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<h2>
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<img src="images/method-index.gif" width=207 height=38 alt="Method Index">
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</h2>
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<dl>
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<dt> <img src="images/red-ball-small.gif" width=6 height=6 alt=" o ">
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<a href="#generateKey()"><b>generateKey</b></a>()
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<dd>
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<dt> <img src="images/red-ball-small.gif" width=6 height=6 alt=" o ">
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<a href="#initialize()"><b>initialize</b></a>()
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<dd> Initialize the KeyGeneratorImpl object.
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</dl>
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<a name="constructors"></a>
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<h2>
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<img src="images/constructors.gif" width=231 height=38 alt="Constructors">
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</h2>
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<a name="KeyGeneratorImpl"></a>
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<a name="KeyGeneratorImpl(java.sql.Connection)"><img src="images/yellow-ball.gif" width=12 height=12 alt=" o "></a>
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<b>KeyGeneratorImpl</b>
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<pre>
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public KeyGeneratorImpl(Connection conn)
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</pre>
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<dl>
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<dd> Construct a new KeyGeneratorImpl object.
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<p>
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<dd><dl>
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<dt> <b>Parameters:</b>
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<dd> conn - A connection to the database containing the XMLDBMSKey table.
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Note that this connection must be different from the connection used by
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the Map object. The reason for this is that each commits transactions at
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different times and using the same connection for both objects would lead
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to statements being committed prematurely.
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</dl></dd>
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</dl>
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<img src="images/methods.gif" width=151 height=38 alt="Methods">
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</h2>
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<a name="initialize()"><img src="images/red-ball.gif" width=12 height=12 alt=" o "></a>
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<a name="initialize"><b>initialize</b></a>
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<pre>
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public void initialize() throws <a href="de.tudarmstadt.ito.xmldbms.KeyException.html#_top_">KeyException</a>
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</pre>
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<dl>
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<dd> Initialize the KeyGeneratorImpl object.
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<p>
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<dd><dl>
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<dt> <b>Throws:</b> <a href="de.tudarmstadt.ito.xmldbms.KeyException.html#_top_">KeyException</a>
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<dd> Thrown if an error occurred initializing the
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database. Usually, this will be an error setting the auto-commit or
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transaction isolation level.
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</dl></dd>
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</dl>
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<a name="generateKey()"><img src="images/red-ball.gif" width=12 height=12 alt=" o "></a>
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<a name="generateKey"><b>generateKey</b></a>
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<pre>
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public Object[] generateKey() throws <a href="de.tudarmstadt.ito.xmldbms.KeyException.html#_top_">KeyException</a>
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</pre>
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<pre>
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<a href="packages.html">All Packages</a> <a href="tree.html">Class Hierarchy</a> <a href="Package-de.tudarmstadt.ito.xmldbms.helpers.html">This Package</a> <a href="Package-de.tudarmstadt.ito.xmldbms.helpers.html">Previous</a> <a href="Package-de.tudarmstadt.ito.xmldbms.helpers.html">Next</a> <a href="AllNames.html">Index</a></pre>
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