001/*
002 * This library is part of OpenCms -
003 * the Open Source Content Management System
004 *
005 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
006 *
007 * This library is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * This library is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * For further information about Alkacon Software, please see the
018 * company website: http://www.alkacon.com
019 *
020 * For further information about OpenCms, please see the
021 * project website: http://www.opencms.org
022 *
023 * You should have received a copy of the GNU Lesser General Public
024 * License along with this library; if not, write to the Free Software
025 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
026 */
027
028package org.opencms.jsp;
029
030import org.opencms.util.CmsRequestUtil;
031
032import javax.servlet.ServletResponse;
033import javax.servlet.http.HttpServletResponse;
034import javax.servlet.jsp.tagext.TagSupport;
035
036/**
037 * A tag to prevent caching by the browser.<p>
038 *
039 * This tag must be used before any other output is written by a JSP.<p>
040 *
041 * @since 8.0.0
042 */
043public class CmsJspTagNoCache extends TagSupport {
044
045    /** Serial version id. */
046    private static final long serialVersionUID = -3571347942237415254L;
047
048    /**
049     * @see javax.servlet.jsp.tagext.Tag#doStartTag()
050     */
051    @Override
052    public int doStartTag() {
053
054        ServletResponse res = pageContext.getResponse();
055        if (res instanceof HttpServletResponse) {
056            CmsRequestUtil.setNoCacheHeaders((HttpServletResponse)pageContext.getResponse());
057        }
058        return SKIP_BODY;
059    }
060}