using xdoclet to have cmp auto-generate primary key values

This may seem like an odd request, but here goes...

I'm using JBoss 3.2.3 with PostgreSQL 7.3.2, and I have a CMP entity bean
(coded using ejbdoclet) that has an integer primary key. The ejbCreate code
currently generates the value for the primary key by doing a "select max(id)
from table", which is really slow because it has to access the database
twice (the select and the insert).

I understand that it's possible to have the entity bean use the database to
auto-generate new primary key values. (With postgres, it has been
recommended to use a database sequence to generate the values.)

Supposedly it's possible to do this in ejbdoclet, but I can't find any
reasonable documentation or an example to copy.  I then discovered that
Middlegen can generate the ejbdoclet file for me.  I downloaded Middlegen
and have been unsuccessful in getting it working in my environment.

But my ultimate goal isn't to get Middlegen running.  All I want is an
example ejbdoclet file for a CMP entity bean that has its primary key value
auto-generated by a PostgreSQL sequence.

Following is the source code for the entity bean.  Could someone show me how
to change it so that the primary key value is auto-generated by a PostgreSQL
sequence?  Or, could someone email me an xdoclet file of some other CMP
entity bean that uses a PostgreSQL sequence to generate the primary key
value?


Thanks,
Mike


--------- ejbdoclet file follows ---------



import javax.ejb.*;
import java.sql.*;


/**
 * @ejb.bean name="Item"
 * jndi-name="Item"
 * local-jndi-name="ItemLocal"
 * type="CMP" cmp-version="2.x"
 * view-type="both"
 *
 * @ejb.home remote-class="com.blah.ejb.entity.item.ItemHome"
 *           local-class="com.blah.ejb.entity.item.ItemLocalHome"
 *
 *
 * @ejb.interface remote-class="com.blah.ejb.entity.item.Item"
 *                local-class="com.blah.ejb.entity.item.ItemLocal"
 *
 * @ejb.persistence table-name="Item"
 *
 * @jboss.persistence create-table="false" remove-table="false"
 *
 * @ejb.transaction type="Required"
 *
 * @ejb.pk class="com.blah.ejb.entity.item.ItemPK"
 *
 */

public abstract class ItemEJB implements EntityBean {

	protected EntityContext entityContext = null;


	///////////////////////////////////////////////////////
	// Container Managed Persistent Fields
	///////////////////////////////////////////////////////

	/**
	 * @ejb.interface-method view-type="both"
	 * @ejb.persistence column-name="itemID"
	 * @ejb:pk-field
	 */
	public abstract int getItemID();

	/**
	 * @ejb.interface-method view-type="both"
	 * @ejb.persistence column-name="itemID"
	 */
	public abstract void setItemID(int itemID);


	/**
	 * @ejb.interface-method view-type="both"
	 * @ejb.persistence column-name="name"
	 */
	public abstract String getName();

	/**
	 * @ejb.interface-method view-type="both"
	 * @ejb.persistence column-name="name"
	 */
	public abstract void setName(String name);


	///////////////////////////////////////////////////////
	// Create methods
	///////////////////////////////////////////////////////

	/**
	 * @ejb.create-method view-type="both"
	 */
	public ItemPK ejbCreate(String name) throws CreateException {
		synchronized(Item.class) {
			int itemID = 0;

			Connection con = null;
			PreparedStatement ps = null;
			try {
				con = JNDICache.getConnection();
				ps = con.prepareStatement("select MAX(ItemID) from ITEM");
				ResultSet rs = ps.executeQuery();
				rs.next();
				itemID = rs.getInt(1) + 1;
				rs.close();
			}
			catch (SQLException se) {
			}
			finally {
				ps.close(); on.close();
			}

			setItemID(itemID);
			setName(name);

			return new ItemPK(itemID);
		}
	}

	public void ejbPostCreate(String name) {
	}


	///////////////////////////////////////////////////////
	// Other required methods
	///////////////////////////////////////////////////////

	public void setEntityContext(EntityContext ec) {
		entityContext = ec;
	}

	public void unsetEntityContext() {
		entityContext = null;
	}

	public void ejbActivate() { }
	public void ejbPassivate() { }
	public void ejbLoad() { }
	public void ejbStore() { }
	public void ejbRemove() { }
}

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