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copied!<p>Implement a custom IdentifierGenerator class; from a <a href="http://blog.anorakgirl.co.uk/2009/01/custom-hibernate-sequence-generator-for-id-field/" rel="nofollow noreferrer">blog post</a>:</p> <pre><code>import java.io.Serializable; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import org.hibernate.HibernateException; import org.hibernate.engine.spi.SessionImplementor; import org.hibernate.id.IdentifierGenerator; public class StringKeyGenerator implements IdentifierGenerator { @Override public Serializable generate(SessionImplementor session, Object collection) throws HibernateException { Connection connection = session.connection(); PreparedStatement ps = null; String result = ""; try { // Oracle-specific code to query a sequence ps = connection.prepareStatement("SELECT TABLE_SEQ.nextval AS TABLE_PK FROM dual"); ResultSet rs = ps.executeQuery(); if (rs.next()) { int pk = rs.getInt("TABLE_PK"); // Convert to a String result = Integer.toString(pk); } } catch (SQLException e) { throw new HibernateException("Unable to generate Primary Key"); } finally { if (ps != null) { try { ps.close(); } catch (SQLException e) { throw new HibernateException("Unable to close prepared statement."); } } } return result; } } </code></pre> <p>Annotate the entity PK like this:</p> <pre><code>@Id @GenericGenerator(name="seq_id", strategy="my.package.StringKeyGenerator") @GeneratedValue(generator="seq_id") @Column(name = "TABLE_PK", unique = true, nullable = false, length = 20) public String getId() { return this.id; } </code></pre> <p>Due to a bug in Eclipse, an error might be raised that the generator (<code>seq_id</code>) is not defined in the persistence unit. Set this to a warning as follows:</p> <ol> <li>Select <strong>Window » Preferences</strong></li> <li>Expand <strong>Java Persistence » JPA » Errors/Warnings</strong></li> <li>Click <strong>Queries and generators</strong></li> <li>Set <strong>Generator is not defined in the persistence unit</strong> to: <code>Warning</code></li> <li>Click <strong>OK</strong> to apply changes and close the dialog</li> </ol>

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