php打印头信息

<?php
header('Content-type: application/json');
session_start();

$headers = apache_request_headers();
$authstr = $_SERVER['HTTP_AUTHORIZATION'];
foreach ($headers as $header => $value){
//   echo "$header: $value <br />\n";
    $_SESSION[$header] = $value;
}
$json = json_encode($headers);
echo $json;
?>