/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source 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.
*
* Resin Open Source 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, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.filters;
import com.caucho.config.types.Period;
import com.caucho.util.Alarm;
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;
import java.io.IOException;
/**
* Caches the servlet output. ExpiresFilter sets the Expires header
* to a time in the filter. The page will be cached until that time
* expires.
*
* <p>The cache-time init-parameter configures how long the page should be
* cached:
*
* <pre>
* <filter>
* <filter-name>expires-cache</filter-name>
* <filter-class>com.caucho.http.filter.ExpiresFilter</filter-class>
* <init-param cache-time='10s'/>
* </filter>
* </pre>
*
* The cache-time allows the standard extensions:
*
* <table>
* <tr><td>s<td>seconds
* <tr><td>m<td>minutes
* <tr><td>h<td>hours
* <tr><td>D<td>days
* <tr><td>W<td>weeks
* <tr><td>M<td>months
* <tr><td>Y<td>years
* </table>
*
* @since Resin 2.0.5
*/
public class ExpiresFilter implements Filter {
/**
* How long to cache the file for.
*/
private long _cacheTime = 2000L;
public void setCacheTime(Period period)
{
_cacheTime = period.getPeriod();
}
/**
* Filter init reads the filter configuration
*/
public void init(FilterConfig config)
throws ServletException
{
String time = config.getInitParameter("cache-time");
if (time != null) {
try {
_cacheTime = Period.toPeriod(time);
} catch (Exception e) {
throw new ServletException(e);
}
}
}
/**
* The filter add an Expires time in the future.
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain nextFilter)
throws ServletException, IOException
{
if (_cacheTime > 0) {
HttpServletResponse res = (HttpServletResponse) response;
res.addHeader("Cache-Control", "max-age=" + (_cacheTime / 1000));
res.setDateHeader("Expires", Alarm.getCurrentTime() + _cacheTime);
}
nextFilter.doFilter(request, response);
}
/**
* Any cleanup for the filter.
*/
public void destroy()
{
}
}