$modified_time = $_SERVER[‘HTTP_IF_MODIFIED_SINCE‘]; if (strtotime($modified_time) + 3600 > time()) { header("HTTP/1.1 304"); exit(1); } header(‘Last-Modified:‘.gmdate("D, d M Y H:i:s")."GMT"); echo time();
原文：http://www.cnblogs.com/gide/p/4558162.html