/**
* Tell the browser to not cache.
*
* <p>This sets several headers to try to ensure that the page will not be cached. Not sure if
* last modified matters -goliver
*
* @param response the HTTP response to which we will add headers.
*/
@Override
public void setNoCache(HttpServletResponse response) {
long past = System.currentTimeMillis() - LONG_EXPIRE;
response.setHeader(HttpHeaders.CACHE_CONTROL, "no-cache, no-store");
response.setHeader(HttpHeaders.PRAGMA, "no-cache");
response.setDateHeader(HttpHeaders.EXPIRES, past);
response.setDateHeader(HttpHeaders.LAST_MODIFIED, past);
}
/**
* Sets cache timeout to a given value.
*
* <p>This sets several headers to try to ensure that the page will be cached for the given length
* of time. Of note is the last-modified header, which is set to a day ago so that browsers
* consider it to be safe.
*
* @param response the HTTP response to which we will add headers.
* @param expiration timeout value in milliseconds.
*/
@Override
public void setCacheTimeout(HttpServletResponse response, long expiration) {
long now = System.currentTimeMillis();
response.setHeader(HttpHeaders.VARY, "Accept-Encoding");
response.setHeader(
HttpHeaders.CACHE_CONTROL, String.format("max-age=%s, public", expiration / 1000));
response.setDateHeader(HttpHeaders.EXPIRES, now + expiration);
response.setDateHeader(HttpHeaders.LAST_MODIFIED, now - SHORT_EXPIRE);
}