$HTTP_RAW_POST_DATA — 原生POST数据
This feature has been DEPRECATED as of PHP 5.6.0. Relying on this feature is highly discouraged.
$HTTP_RAW_POST_DATA 包含 POST 提交的原始数据。参见 always_populate_raw_post_data
一般而言，使用 php://input 代替 $HTTP_RAW_POST_DATA。