GWTCacheControlFilter.java

package org.aplikator.server;


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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Date;

/**
 * {@link Filter} to add cache control headers for GWT generated files to ensure
 * that the correct files get cached.
 *
 * @author See Wah Cheng
 * @created 24 Feb 2009
 */
@WebFilter(
        filterName = "GWTCacheControlFilter",
        urlPatterns = {"/*"})
public class GWTCacheControlFilter implements Filter {

    public void destroy() {
    }

    public void init(FilterConfig config) throws ServletException {
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException,
            ServletException {

        HttpServletRequest httpRequest = (HttpServletRequest) request;
        String requestURI = httpRequest.getRequestURI();

        if (requestURI.contains(".nocache.")) {
            Date now = new Date();
            HttpServletResponse httpResponse = (HttpServletResponse) response;
            httpResponse.setDateHeader("Date", now.getTime());
            // one day old
            httpResponse.setDateHeader("Expires", now.getTime() - 86400000L);
            httpResponse.setHeader("Pragma", "no-cache");
            httpResponse.setHeader("Cache-control", "no-cache, no-store, must-revalidate");
        }

        filterChain.doFilter(request, response);
    }
}