/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed under the Apache license, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.internna.iwebmvc.core.jee;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;
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.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Adds a Cache-Control header if needed
*
* @author Jose Noheda
* @since 1.0
*/
public class CacheFilter implements Filter {
private int seconds;
private FilterConfig filterConfig;
private DateFormat httpDateFormat;
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
seconds = Integer.parseInt(filterConfig.getInitParameter("Cache-Control"));
httpDateFormat = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss z", Locale.US);
httpDateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
}
public void destroy() {
this.filterConfig = null;
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
if (request instanceof HttpServletRequest) {
filterChain.doFilter(request, response);
HttpServletResponse httpResponse = (HttpServletResponse) response;
httpResponse.setHeader("Pragma", "public");
Calendar cal = new GregorianCalendar();
cal.roll(Calendar.SECOND, seconds);
httpResponse.setHeader("Cache-Control", "PUBLIC, max-age=" + seconds + ", must-revalidate");
httpResponse.setHeader("Expires", httpDateFormat.format(cal.getTime()));
}
}
}