if(isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && (time()-strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) < 3600*24)) {
     header(“HTTP/1.1 304 Not Modified”);
     exit;
   }
   header(“Last-Modified: ” . gmdate(‘D, d M Y H:i:s \G\M\T’, time()) );

expires:不大好用，直接敲还是会访问，这个虽然占服务器连接，但是至少他304，后面的不执行了。

array_filter(array(’2356′,”,’235′,’677′), ‘strlen’);

空会被过滤，剩下2356 235和677

function getAbsolutePath($path) {
        $path = str_replace(array(‘/’, ‘\\’), DIRECTORY_SEPARATOR, $path);
        $parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), ‘strlen’); //过滤掉空。。
        $absolutes = array();
        foreach ($parts as $part) {
            if (‘.’ == $part) continue;
            if (‘..’ == $part) {
                array_pop($absolutes);
            } else {
                $absolutes[] = $part;
            }
        }
        return DIRECTORY_SEPARATOR.implode(DIRECTORY_SEPARATOR, $absolutes);
}

error_reporting(E_ALL);
ini_set(“display_errors”, 1);