/**
* The modified date response header is used by the client for content caching. It seems obvious
* that if we have a modified date on the resource we should set it. BUT, because of the
* interaction with max-age we should always set it to the current date if we have max-age The
* problem, is that if we find that a condition GET has an expired mod-date (based on maxAge) then
* we want to respond with content (even if our mod-date hasnt changed. But if we use the actual
* mod-date in that case, then the browser will continue to use the old mod-date, so will forever
* more respond with content. So we send a mod-date of now to ensure that future requests will be
* given a 304 not modified.*
*
* @param response
* @param resource
* @param auth
*/
public static void setModifiedDate(Response response, Resource resource, Auth auth) {
Date modDate = resource.getModifiedDate();
if (modDate != null) {
// HACH - see if this helps IE
response.setLastModifiedHeader(modDate);
// if (resource instanceof GetableResource) {
// GetableResource gr = (GetableResource) resource;
// Long maxAge = gr.getMaxAgeSeconds(auth);
// if (maxAge != null && maxAge > 0) {
// log.trace("setModifiedDate: has a modified date and a positive maxAge,
// so adjust modDate");
// long tm = System.currentTimeMillis() - 60000; // modified 1 minute ago
// modDate = new Date(tm); // have max-age, so use current date
// }
// }
// response.setLastModifiedHeader(modDate);
}
}
@Override
public void respondNotModified(GetableResource resource, Response response, Request request) {
log.trace("respondNotModified");
response.setStatus(Response.Status.SC_NOT_MODIFIED);
response.setDateHeader(new Date());
String etag = eTagGenerator.generateEtag(resource);
if (etag != null) {
response.setEtag(etag);
}
// Note that we use a simpler modified date handling here then when
// responding with content, because in a not-modified situation the
// modified date MUST be that of the actual resource
Date modDate = resource.getModifiedDate();
response.setLastModifiedHeader(modDate);
cacheControlHelper.setCacheControl(resource, response, request.getAuthorization());
}