com.mercatis.lighthouse3.persistence.commons.hibernate.UnitOfWorkImplementation.java Source code

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Here is the source code for com.mercatis.lighthouse3.persistence.commons.hibernate.UnitOfWorkImplementation.java

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/*
 * Copyright 2011 mercatis Technologies AG
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.mercatis.lighthouse3.persistence.commons.hibernate;

import org.apache.log4j.Logger;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.SessionFactoryImplementor;

import com.mercatis.lighthouse3.domainmodel.commons.PersistenceException;
import com.mercatis.lighthouse3.domainmodel.commons.UnitOfWork;

public class UnitOfWorkImplementation implements UnitOfWork {

    protected Logger log = Logger.getLogger(this.getClass());

    /**
     * This field maintains the reference to the Hibernate session factory
     * underlying the current unit of work.
     */
    private static SessionFactory sessionFactory = null;

    /**
     * This property keeps a reference to the SQL dialect of the database
     * underlying the DAO implementation
     */
    private Dialect sqlDialect = null;

    /**
     * This method return the Hibernate SQL dialect of the database underlying
     * the unit of work implementation.
     * 
     * @return the Hibernate SQL dialect
     */
    public Dialect getSqlDialect() {
        if ((this.sqlDialect == null) && (sessionFactory != null))
            this.sqlDialect = ((SessionFactoryImplementor) sessionFactory).getDialect();

        return this.sqlDialect;
    }

    /**
     * This map maintains closing-safe thread local Hibernate sessions. As one
     * may instantiate several Hibernate-based DAOs pointing to the same session
     * factory, it is important that this map is global.
     */
    private static ThreadLocal<Session> threadLocalSessions = null;

    /**
     * Set the Hibernate session factory to use for the current unit of work.
     * 
     * @param sessionFactory
     *            the session factory to use for the current unit of work
     */
    public void setSessionFactory(SessionFactory factory) {
        if (factory != sessionFactory) {
            threadLocalSessions = new ThreadLocal<Session>();
            sessionFactory = factory;
        }
    }

    /**
     * This method returns the Hibernate session factory used for the current
     * unit of work.
     * 
     * @return the session factory.
     */
    public SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    /**
     * Returns the current hibernate session for the unit of work.
     * 
     * @return the hibernate session
     */
    public Session getCurrentSession() {
        Session session = threadLocalSessions.get();

        if (session == null) {
            try {
                if (log.isDebugEnabled()) {
                    log.debug("UnitOfWork: Open Session, SessionFactory: "
                            + System.identityHashCode(this.getSessionFactory()));
                }
                session = this.getSessionFactory().openSession();
                session.setDefaultReadOnly(true);

                if (!session.getTransaction().isActive())
                    session.beginTransaction();

                threadLocalSessions.set(session);
            } catch (Exception e1) {
                try {
                    session.close();
                    threadLocalSessions.set(null);
                } catch (Exception e2) {
                    log.error(e2.getMessage(), e2);
                }

                throw new PersistenceException("Could not open new session", e1);
            }
        }
        if (log.isDebugEnabled()) {
            log.debug("UnitOfWork: Providing Session: " + System.identityHashCode(session));
        }
        return session;
    }

    public void commit() {
        Session session = null;
        try {
            session = threadLocalSessions.get();
            if (session == null) {
                return;
            }

            if (log.isDebugEnabled()) {
                log.debug("UnitOfWork: Commit Session: " + System.identityHashCode(session));
            }

            session.getTransaction().commit();
        } catch (Exception e1) {
            log.error(e1.getMessage(), e1);
            throw new PersistenceException("Could not commit transaction", e1);
        } finally {
            try {
                if (session != null) {
                    session.close();
                    threadLocalSessions.set(null);
                }
            } catch (Exception e2) {
                log.error(e2.getMessage(), e2);
            }
        }
    }

    public void flush() {
        Session session = null;
        try {
            session = threadLocalSessions.get();
            if (session == null) {
                return;
            }

            if (log.isDebugEnabled()) {
                log.debug("UnitOfWork: Flush Session: " + System.identityHashCode(session));
            }

            session.flush();
            session.clear();
        } catch (Exception cause) {
            throw new PersistenceException("Could not flush unit of work", cause);
        }
    }

    public void rollback() {
        Session session = null;
        try {
            session = threadLocalSessions.get();
            if (session == null) {
                return;
            }

            if (log.isDebugEnabled()) {
                log.debug("UnitOfWork: Rollback Session: " + System.identityHashCode(session));
            }

            session.getTransaction().rollback();
        } catch (Exception e1) {
            log.error(e1.getMessage(), e1);
            throw new PersistenceException("Could not commit transaction", e1);
        } finally {
            try {
                if (session != null) {
                    session.close();
                    threadLocalSessions.set(null);
                }
            } catch (Exception e2) {
                log.error(e2.getMessage(), e2);
            }
        }
    }

    public void setReadOnly(Object o, boolean readOnly) {
        Session session = threadLocalSessions.get();
        if (session == null) {
            return;
        }

        if (session.contains(o) && session.isReadOnly(o) != readOnly) {
            if (log.isDebugEnabled()) {
                log.debug(
                        "UnitOfWork: SetReadOnly: " + readOnly + ", Session: " + System.identityHashCode(session));
            }
            session.setReadOnly(o, readOnly);
        }
    }
}