package jpl.hibernate.util;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import org.hibernate.HibernateException;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.id.AbstractPostInsertGenerator;
import org.hibernate.id.IdentifierGeneratorFactory;
import org.hibernate.id.PostInsertIdentityPersister;
import org.hibernate.id.SequenceIdentityGenerator.NoCommentsInsert;
import org.hibernate.id.insert.AbstractReturningDelegate;
import org.hibernate.id.insert.IdentifierGeneratingInsert;
import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;
import org.hibernate.util.NamedGeneratedKeysHelper;

/**
* A generator with immediate retrieval through JDBC3 {@link java.sql.Connection#prepareStatement(String, String[]) getGeneratedKeys}.
* The value of the identity column must be set from a "before insert trigger"
* <p/>
* This generator only known to work with newer Oracle drivers compiled for
* JDK 1.4 (JDBC3). The minimum version is 10.2.0.1
* <p/>
* Note: Due to a bug in Oracle drivers, sql comments on these insert statements
* are completely disabled.
*
* @author Jean-Pol Landrain
*/
public class TriggerAssignedIdentityGenerator extends AbstractPostInsertGenerator {

    public InsertGeneratedIdentifierDelegate getInsertGeneratedIdentifierDelegate(PostInsertIdentityPersister persister, Dialect dialect, boolean isGetGeneratedKeysEnabled) throws HibernateException {
        return new Delegate(persister, dialect);
    }

    public static class Delegate extends AbstractReturningDelegate {
        private final Dialect dialect;

        private final String[] keyColumns;

        public Delegate(PostInsertIdentityPersister persister, Dialect dialect) {
            super(persister);
            this.dialect = dialect;
            this.keyColumns = getPersister().getRootTableKeyColumnNames();
            if (keyColumns.length > 1) {
                throw new HibernateException("trigger assigned identity generator cannot be used with multi-column keys");
            }
        }

        public IdentifierGeneratingInsert prepareIdentifierGeneratingInsert() {
            NoCommentsInsert insert = new NoCommentsInsert(dialect);
            return insert;
        }

        protected PreparedStatement prepare(String insertSQL, SessionImplementor session) throws SQLException {
            return session.getBatcher().prepareStatement(insertSQL, keyColumns);
        }

        protected Serializable executeAndExtract(PreparedStatement insert) throws SQLException {
            insert.executeUpdate();
            return IdentifierGeneratorFactory.getGeneratedIdentity(NamedGeneratedKeysHelper.getGeneratedKey(insert), getPersister().getIdentifierType());
        }
    }
}

        <id name="id"
            column="MECA_UID">
                <generator class="jpl.hibernate.util.TriggerAssignedIdentityGenerator" />
        </id>

14 gen 2008 22:15:25,991  WARN [Portal Admin] JDBCExceptionReporter  - SQL Error: 17023, SQLState: null
14 gen 2008 22:15:25,992 ERROR [Portal Admin] JDBCExceptionReporter  - Function unsupported
org.hibernate.exception.GenericJDBCException: could not insert: ..............

<id name="id" type="big_decimal">
    <column name="ID" precision="22" scale="0" />
    <generator class="TriggerAssignedIdentityGenerator" />
</id>

@Id @GeneratedValue(generator="triggerAssigned")
@GenericGenerator(name="triggerAssigned",
  strategy = "jpl.hibernate.util.TriggerAssignedIdentityGenerator"
)
@Column(name="MECA_UID")
public Long getId() { ... }

CREATE OR REPLACE TRIGGER "SCHEMA_NAME".TG_MEETING_CATEGORY
BEFORE INSERT
ON MEETING_CATEGORY
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
BEGIN
SELECT SEQ_MEETING_CATEGORY.NEXTVAL INTO :NEW.MECA_UID FROM DUAL;
END TG_MEETING_CATEGORY;

package org.hibernate.id;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import oracle.jdbc.OraclePreparedStatement;
import oracle.jdbc.OracleTypes;

import org.apache.commons.lang.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.id.SequenceIdentityGenerator.NoCommentsInsert;
import org.hibernate.id.insert.AbstractReturningDelegate;
import org.hibernate.id.insert.IdentifierGeneratingInsert;
import org.hibernate.id.insert.InsertGeneratedIdentifierDelegate;

/**
* A generator with immediate retrieval through JDBC3
* {@link java.sql.Connection#prepareStatement(String)}. The value of the identity column must be
* set from a "before insert trigger" <p/> This generator only known to work with newer Oracle
* drivers compiled for JDK 1.4 (JDBC3). The minimum version is 10.2.0.1 <p/> Note: Due to a bug in
* Oracle drivers, sql comments on these insert statements are completely disabled.
*
* This class dos not use the method
* {@link java.sql.Connection#prepareStatement(String, String[]) getGeneratedKeys} because with this
* method the driver wants get the return type form the database meta. If the application user is
* not the shemaowner, this is not possible. This is the reason why the ReturnParameter is hard set
* to Long.
*
* @author Jean-Pol Landrain
* @author Beat Sager
*/
public class TriggerAssignedIdentityGenerator extends AbstractPostInsertGenerator {
    private static final String RETURN_PREFIX = " RETURNING ";
    private static final String RETURN_SUFFIX = " INTO ?";
    private static final String Q_MARK = "?";

    public InsertGeneratedIdentifierDelegate getInsertGeneratedIdentifierDelegate(
            PostInsertIdentityPersister persister, Dialect dialect,
            boolean isGetGeneratedKeysEnabled) throws HibernateException {
        return new Delegate(persister, dialect);
    }

    public static class Delegate extends AbstractReturningDelegate {
        private final Dialect dialect;
        private final String sqlSuffix;

        public Delegate(PostInsertIdentityPersister persister, Dialect dialect) {
            super(persister);
            this.dialect = dialect;
            String[] keyColumns = getPersister().getRootTableKeyColumnNames();
            if (keyColumns.length > 1) {
                throw new HibernateException(
                        "trigger assigned identity generator cannot be used with multi-column keys");
            }
            sqlSuffix = new StringBuffer(26).append(RETURN_PREFIX).append(keyColumns[0]).append(
                    RETURN_SUFFIX).toString();
        }

        public IdentifierGeneratingInsert prepareIdentifierGeneratingInsert() {
            return new NoCommentsInsert(dialect);
        }

        protected PreparedStatement prepare(String insertSQL, SessionImplementor session)
                throws SQLException {
            insertSQL += sqlSuffix;
            OraclePreparedStatement stmt = (OraclePreparedStatement) session.getBatcher()
                    .prepareStatement(insertSQL);
            stmt.registerReturnParameter(StringUtils.countMatches(insertSQL, Q_MARK),
                    OracleTypes.NUMBER);
            return stmt;
        }

        protected Serializable executeAndExtract(PreparedStatement statement) throws SQLException {
            OraclePreparedStatement insert = (OraclePreparedStatement) statement;
            if (insert.executeUpdate() > 0) {
                ResultSet resultSet = insert.getReturnResultSet();
                if (resultSet.next()) {
                    return new Long(resultSet.getLong(1));
                }
            }
            throw new SQLException("Returned no id in resultset");
        }
    }
}