a new servletfilter, which controls the caching-values in the http-header.\ra new...

[mir.git] / source / mir / core / ui / filter / CachingFilter.java

diff --git a/source/mir/core/ui/filter/CachingFilter.java b/source/mir/core/ui/filter/CachingFilter.java
new file mode 100755 (executable)
index 0000000..33446ba
--- /dev/null
+++ b/source/mir/core/ui/filter/CachingFilter.java
@@ -0,0 +1,105 @@
+/*
+ * 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;
+       }
+
+}