hibernatesession.java

关于HEBERNATE使用的一个简单例子

package dbdemo.util.hibernate;

import java.sql.Connection;
import java.sql.SQLException;

import org.apache.log4j.Logger;

import cirrus.hibernate.Datastore;
import cirrus.hibernate.Hibernate;
import cirrus.hibernate.HibernateException;
import cirrus.hibernate.MappingException;
import cirrus.hibernate.Session;
import cirrus.hibernate.SessionFactory;
import dbdemo.User;
import dbdemo.Address;
import dbdemo.Book;
import dbdemo.Contact;
import dbdemo.exception.HibernateException;
import dbdemo.portal.UserContainer;
import dbdemo.util.DatasourceFactory;

/**
 * @author MEagle
 * 
 * This is for Hibernate version 1.x
 *
 * Hibernate is designed to be useable in any kind of Java application,
 * including applications that make extensive use of multithreading. So,
 * unlike the ODMG API, Hibernate's native API does not use the current
 * thread to maintain associations between Session and Transaction or
 * between Session and application thread. This can be inconvenient for
 * J2EE applications where access to a Session instance is always from
 * a particular thread. It is particularly inconvenient when using a DAO
 * pattern, when the different DAO classes need to obtain the (same)
 * current session.
 *
 *
 * A thread-local variable effectively provides a separate copy of its
 * value for each thread that uses it. Each thread can see only the value
 * associated with that thread, and is unaware that other threads may be
 * using or modifying their own copies.
 */
public class HibernateSession {

	// Add a Log4J logger
	static Logger log = Logger.getLogger(HibernateSession.class.getName());

	static Datastore dataStore = null;
	static SessionFactory sf = null;

	static {
		try {
			init();
		} catch (HibernateException e) {
			log.error("could not init " + e.getMessage());
		}
	}

	public static final ThreadLocal local = new ThreadLocal();

	/**
	 * Retrieve the current Hibernate Session object via the ThreadLocal
	 * class.
	 *
	 * @param uc - the user's container object stored in the session
	 * @return Session
	 * @throws HibernateException
	 *
	 */
	public static Session currentSession(UserContainer uc)
		throws HibernateException {

		Session session = currentSession();

		log.info(
			session
				+ " "
				+ uc.getFullName()
				+ " HibernateSession:currentSession");
		return session;
	}

	/**
	 * Retrieve the current Hibernate Session object via the ThreadLocal
	 * class.
	 *
	 * @return Session
	 * @throws HibernateException
	 *
	 */
	public static Session currentSession() throws HibernateException {

		Session session = (Session) local.get();
		if (session == null) {

			Connection con = null;

			// create a datasource object
			if (sf == null) {
				init();
			}

			try {
				// get a connnection from a pool
				con = DatasourceFactory.getConnection();

				// create a session object to the database
				session = sf.openSession(con);

			} catch (SQLException sqle) {
				log.error("SQLException: " + sqle.getMessage());
				throw new HibernateException("SQLException: " + sqle.getMessage());
			}
			local.set(session);
		}

		return session;
	}

	/**
	 * Close the Hibernate Session and any underlying Connection
	 * for further cleanup
	 *
	 * @param uc - the user's container object stored in the session
	 * @throws HibernateException, SQLException
	 */
	public static void closeSession(UserContainer uc)
		throws HibernateException, SQLException {

		String hashCode = closeSession();

		log.info(
			hashCode
				+ " "
				+ uc.getFullName()
				+ " HibernateSession:closeSession");
	}

	/**
	 * Close the Hibernate Session and any underlying Connection
	 * for further cleanup
	 *
	 * @param uc - the user's container object stored in the session
	 * @return String - the hashcode of the session object that was closed
	 * 					for debug purposes
	 * @throws HibernateException, SQLException
	 */
	public static String closeSession()
		throws HibernateException, SQLException {
		Connection con = null;

		Session session = (Session) local.get();

		String sessionHashCode = session.toString();

		local.set(null);
		if (session != null) {
			con = session.close();
		}

		if (con != null) {
			con.close();
		}

		return sessionHashCode;
	}

	private static synchronized void init() throws HibernateException {
		try {

			dataStore = Hibernate.createDatastore();

			// load up the different configurations
			dataStore
				.storeClass(User.class)
				.storeClass(Address.class)
				.storeClass(Contact.class)
				.storeClass(Book.class);

			sf = dataStore.buildSessionFactory();
			System.out.println(
				"HibernateSession Initialized SessionFactory=" + sf);
		} catch (MappingException me) {
			log.error(
				"Could not intialize Hibernate session factory. "
					+ me.getMessage());
			throw new HibernateException(
				"Could not intialize Hibernate session factory. "
					+ me.getMessage());
		} catch (HibernateException he) {
			log.error(
				"Could not intialize Hibernate session factory. "
					+ he.getMessage());
			throw new HibernateException(
				"Could not intialize Hibernate session factory. "
					+ he.getMessage());
		}
	}
}