>## 获取请求头信息 ``` // 获取所有请求头信息 $info = Request::instance()->header(); echo $info['accept']; echo $info['accept-encoding']; echo $info['user-agent']; // 获取请求头的某个属性 $agent = Request::instance()->header('user-agent'); // 获取的时候不区分大小写，并且_会转化为-，以下写法等效 $agent = Request::instance()->header('user-agent'); $agent = Request::instance()->header('User-Agent'); $agent = Request::instance()->header('USER_AGENT' ```