us.opulo.p.hibernate.SessionManager.java Source code

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Here is the source code for us.opulo.p.hibernate.SessionManager.java

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/**
 * This file is a component of the p.opulo.us project.
 *
 * Copyright (c) 2013 Jason Campos <jcampos8782@gmail.com>, Shaun Guth, Ash Islam
 * All Rights Reserved.
 *
 * This software is licensed under The MIT License (MIT)
 * http://opensource.org/licenses/MIT
 */
package us.opulo.p.hibernate;

import org.hibernate.Session;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Provides basic Session management for hibernate. Tracks Sessions on a per-thread basis. Does NOT include 
 * automatic session closing. Care must be taken to close open Hibernate connections.
 *  
 * @author Jason Campos
 */
public class SessionManager {
    private static final Logger log = LoggerFactory.getLogger(SessionManager.class);

    // The active sessions
    private static final ThreadLocal<Session> ACTIVE_SESSIONS = new ThreadLocal<>();

    private static final String DUPLICATE_SESSION = "An active session is already open for this thread.";
    private static final String INVALID_SESSION = "No active session exists for this thread.";

    /**
     * Set the Session for the current thread.
     * @param session The Hibernate Session which belongs to this thread.
     * @throws IllegalStateException Thrown if a session already exists.
     */
    public static synchronized final void set(Session session) {
        log.debug("Session initialized");
        if (ACTIVE_SESSIONS.get() != null) {
            throw new IllegalStateException(DUPLICATE_SESSION);
        }

        // Set the session for the current thread
        ACTIVE_SESSIONS.set(session);
    }

    /**
     * Retrieves the Session for the current thread.
     * @return The Session for the current thread of {@code null} if one does not exist.
     */
    public static synchronized final Session get() {
        return ACTIVE_SESSIONS.get();
    }

    /**
     * Closes the session for the current thread.
     * @throws IllegalStateException Thrown if the session is already closed. 
     */
    public static synchronized final void close() {
        Session session = ACTIVE_SESSIONS.get();

        if (session == null) {
            throw new IllegalStateException(INVALID_SESSION);
        }

        if (session.isConnected()) {
            session.flush();
            session.disconnect();
            session.close();
            ACTIVE_SESSIONS.remove();
            log.debug("Session closed");
        }
    }
}