org.opencms.jsp.CmsJspTagNoCache Maven / Gradle / Ivy

/*
 * This library is part of OpenCms -
 * the Open Source Content Management System
 *
 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * For further information about Alkacon Software, please see the
 * company website: http://www.alkacon.com
 *
 * For further information about OpenCms, please see the
 * project website: http://www.opencms.org
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.opencms.jsp;

import org.opencms.util.CmsRequestUtil;

import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.tagext.TagSupport;

/**
 * A tag to prevent caching by the browser.
 *
 * This tag must be used before any other output is written by a JSP.
 *
 * @since 8.0.0
 */
public class CmsJspTagNoCache extends TagSupport {

    /** Serial version id. */
    private static final long serialVersionUID = -3571347942237415254L;

    /**
     * @see javax.servlet.jsp.tagext.Tag#doStartTag()
     */
    @Override
    public int doStartTag() {

        ServletResponse res = pageContext.getResponse();
        if (res instanceof HttpServletResponse) {
            CmsRequestUtil.setNoCacheHeaders((HttpServletResponse)pageContext.getResponse());
        }
        return SKIP_BODY;
    }
}