/*
 *  DLOG_HibernateFilter.java
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *  
 *  Author: Winter Lau
 *  http://dlog4j.sourceforge.net
 *  
 */
package com.liusoft.dlog4j.servlet;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.hibernate.HibernateException;

import com.liusoft.dlog4j.Globals;
import com.liusoft.dlog4j.db.HibernateUtils;

/**
 * A servlet filter that opens and closes a Hibernate Session for each request.
 * <p>
 * This filter guarantees a sane state, committing any pending database
 * transaction once all other filters (and servlets) have executed. It also
 * guarantees that the Hibernate <tt>Session</tt> of the current thread will
 * be closed before the response is send to the client.
 * <p>
 * Use this filter for the <b>session-per-request</b> pattern and if you are
 * using <i>Detached Objects</i>.
 *
 * @see HibernateUtils
 * @author Christian Bauer <christian@hibernate.org>
 */
public class DLOG_HibernateFilter implements Filter {
	
	private ServletContext context = null;
	private boolean commit_on_close = false;

	public void init(FilterConfig filterConfig) throws ServletException {	
		context = filterConfig.getServletContext();
		if(Globals.WEBAPP_PATH==null)
			Globals.WEBAPP_PATH = context.getRealPath("");
		commit_on_close = "true".equalsIgnoreCase(filterConfig
				.getInitParameter("commit_on_close")); 
	}

	/**
	 * 請求完畢后釋放數據庫資源
	 */
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		try {
			// We don't start the database transaction here, but when first needed
			chain.doFilter(request, response);			
			//User must commit the transaction manual
			if(commit_on_close){
				HibernateUtils.commit();
			}
		} catch(HibernateException e) {
			if(commit_on_close){
				HibernateUtils.rollback();
			}
		} finally {
			// No matter what happens, close the Session.
			try {
				HibernateUtils.closeSession();
			} catch (HibernateException ex) {
				if(context!=null)
					context.log("Exception when close hibernate session", ex);
			}
		}
	}

	public void destroy() {
		// 釋放Hibernate
		HibernateUtils.destroy();
	}

}