Hibernate kickstart

A quick’n dirty tutorial-by-example for Hibernate:
(Using one table, an Oracle9+ database and Hibernate2)

1) download the Hibernate distribution

2) put these jarfiles in /WEB-INF/lib:

hibernate2.jar (hibernate core)
cglib-full-2.0.2.jar (runtime class-enhancing)
dom4j-1.4.jar (xml reading)
ehcache-0.9.jar (objectcache)
c3p0-0.8.4.5.jar (connectionpool)
jta.jar (transactions)

3) put this xml-file in your classpath (as /WEB-INF/classes/hibernate.cfg.xml):

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 2.0//EN"
	"http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">
<hibernate-configuration>
	<session-factory>
        <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="connection.url">jdbc:oracle:thin:@yourDBserver:port:name</property>
        <property name="connection.username">uid</property>
        <property name="connection.password">pass</property>

        <property name="show_sql">true</property>
        <property name="dialect">net.sf.hibernate.dialect.Oracle9Dialect</property>

        <property name="c3p0.min_size">5</property>
        <property name="c3p0.max_size">20</property>
        <property name="c3p0.timeout">1800</property>
        <property name="c3p0.max_statements">50</property>

        <mapping resource="nl/amis/bookreviewstruts/bean/Review.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

4) Assuming this table:

TABLE BR_REVIEW (
    REVIEWID NUMBER NOT NULL,
    BOOKTITLE VARCHAR2 (255) NOT NULL,
    ISBN VARCHAR2 (100) NOT NULL,
    AUTHORS VARCHAR2 (255),
    PUBLISHER VARCHAR2 (100),
    REVIEWTITLE VARCHAR2 (255),
    REVIEWERS VARCHAR2 (255),
    APPRECIATION NUMBER
)

and a javabean like this:

public class Review
{
    private long reviewId;
    [..]
    public long getReviewId() { return this.reviewId;}
    public void setReviewId(long reviewId) { this.reviewId = reviewId;}
    [..]
}

create nl/amis/bookreviewstruts/bean/Review.hbm.xml:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
    PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">
<hibernate-mapping>
    <class name="nl.amis.bookreviewstruts.bean.Review" table="BR_REVIEW">
        <id name="reviewId" unsaved-value="-1">
            <generator class="native"/>
        </id>
        <property name="bookTitle" not-null="true"/>
        [..]
    </class>
</hibernate-mapping>

5) Create the HibernateUtil class:

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class HibernateUtil {
    private static Log log = LogFactory.getLog(HibernateUtil.class);
    private static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            log.error("Initial SessionFactory creation failed.", ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static final ThreadLocal session = new ThreadLocal();

    public static Session currentSession() throws HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this Thread has none yet
        if (s == null) {
            s = sessionFactory.openSession();
            session.set(s);
        }
        return s;
    }

    public static void closeSession() throws HibernateException {
        Session s = (Session) session.get();
        session.set(null);
        if (s != null)
            s.close();
    }
}

6) That’s it! Now for example query for all results:

    Session session = HibernateUtil.currentSession();
    List allReviews = session.find("from Review");
    HibernateUtil.closeSession();

More about querying and manipulating data can be found here, here, here or here