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}