package org.appfuse.webapp.filter;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.displaytag.tags.TableTagParameters;
import org.springframework.web.filter.OncePerRequestFilter;
public class GZIPFilter extends OncePerRequestFilter {
private final transient Log log = LogFactory.getLog(GZIPFilter.class);
public void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
FilterChain chain)
throws IOException, ServletException {
if (isGZIPSupported(request)) {
if (log.isDebugEnabled()) {
log.debug("GZIP supported, compressing response");
}
GZIPResponseWrapper wrappedResponse =
new GZIPResponseWrapper(response);
chain.doFilter(request, wrappedResponse);
wrappedResponse.finishResponse();
return;
}
chain.doFilter(request, response);
}
private boolean isGZIPSupported(HttpServletRequest req) {
String exporting = req.getParameter(TableTagParameters.PARAMETER_EXPORTING);
if (exporting != null) {
log.debug("detected excel export, disabling filter...");
return false;
}
String browserEncodings = req.getHeader("accept-encoding");
boolean supported = ((browserEncodings != null) &&
(browserEncodings.indexOf("gzip") != -1));
String userAgent = req.getHeader("user-agent");
if ((userAgent != null) && userAgent.startsWith("httpunit")) {
log.debug("httpunit detected, disabling filter...");
return false;
} else {
return supported;
}
}
}