+/*
+ * CachingFilter.java created on 04.09.2003
+ *
+ * Copyright (C) 2001, 2002, 2003 The Mir-coders group
+ *
+ * This file is part of Mir.
+ *
+ * Mir 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.
+ *
+ * Mir 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Mir; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * In addition, as a special exception, The Mir-coders gives permission to link
+ * the code of this program with any library licensed under the Apache Software License,
+ * The Sun (tm) Java Advanced Imaging library (JAI), The Sun JIMI library
+ * (or with modified versions of the above that use the same license as the above),
+ * and distribute linked combinations including the two. You must obey the
+ * GNU General Public License in all respects for all of the code used other than
+ * the above mentioned libraries. If you modify this file, you may extend this
+ * exception to your version of the file, but you are not obligated to do so.
+ * If you do not wish to do so, delete this exception statement from your version.
+ */
+package mir.core.ui.filter;
+
+import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.GregorianCalendar;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * CachingFilter
+ * @author idefix
+ * @version $Id: CachingFilter.java,v 1.1 2003/09/18 21:42:17 idfx Exp $
+ */
+public class CachingFilter implements Filter {
+ private final static String EXPIRATION_DATE;
+ private FilterConfig _filterConfig;
+
+ static {
+ // Generate expiration date that is one year from now in the past
+ GregorianCalendar expiration = new GregorianCalendar();
+ expiration.roll(Calendar.YEAR, -1);
+ SimpleDateFormat httpDate =
+ new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", java.util.Locale.US);
+ EXPIRATION_DATE = httpDate.format(expiration.getTime());
+ }
+
+ /**
+ *
+ */
+ public CachingFilter() {
+ super();
+ }
+
+ /**
+ * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
+ */
+ public void init(final FilterConfig filterConfig)
+ throws ServletException {
+ _filterConfig = filterConfig;
+ }
+
+ /**
+ * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
+ */
+ public void doFilter(ServletRequest servletRequest,
+ ServletResponse servletResponse, FilterChain filterChain)
+ throws IOException, ServletException {
+
+ filterChain.doFilter(servletRequest, servletResponse);
+
+ HttpServletResponse response = (HttpServletResponse) servletResponse;
+ // HTTP 1.1 browsers should defeat caching on this header
+ response.setHeader( "Cache-Control" ,"no-cache" );
+ // HTTP 1.0 browsers should defeat caching on this header
+ response.setHeader( "Pragma" ,"no-cache" );
+ // Last resort for those that ignore all of the above
+ response.setHeader( "Expires" , EXPIRATION_DATE);
+ }
+
+ /**
+ * @see javax.servlet.Filter#destroy()
+ */
+ public void destroy() {
+ _filterConfig = null;
+ }
+
+}