package org.platformlayer.xaas.web;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
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;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.fathomdb.TimeSpan;
public class GwtCacheHeaderFilter implements Filter {
private static final Logger log = LoggerFactory.getLogger(GwtCacheHeaderFilter.class);
public static final String DATE_PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
ServletException {
if (response instanceof HttpServletResponse) {
String requestUri = ((HttpServletRequest) request).getRequestURI();
HttpServletResponse httpServletResponse = (HttpServletResponse) response;
TimeSpan cacheFor = null;
if (requestUri.contains(".cache.")) {
// Cache forever
cacheFor = TimeSpan.ONE_DAY.multiplyBy(365);
} else if (requestUri.contains(".nocache.")) {
// Don't ever cache
cacheFor = null;
} else {
// Micro cache
cacheFor = TimeSpan.TEN_MINUTES;
}
if (cacheFor == null) {
httpServletResponse.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
httpServletResponse.setHeader("Expires", "0");
} else {
long now = System.currentTimeMillis() / 1000L;
long timeoutAt = now + cacheFor.getTotalSeconds();
long deltaSeconds = timeoutAt - now;
httpServletResponse.setHeader("Cache-Control", "max-age=" + deltaSeconds);
SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_PATTERN_RFC1123);
String expires = dateFormat.format(new Date(timeoutAt * 1000L));
httpServletResponse.setHeader("Expires", expires);
}
}
chain.doFilter(request, response);
}
@Override
public void destroy() {
}
}