PHP中获取页面的URL

var_dump($_SERVER);die();

array (size=42)
'HTTP_HOST' =>  'localhost' (length=9)
'HTTP_CONNECTION' =>  'keep-alive' (length=10)
'CONTENT_LENGTH' =>  '377' (length=3)
'HTTP_CACHE_CONTROL' =>  'max-age=0' (length=9)
'HTTP_ACCEPT' =>  'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' (length=74)
'HTTP_ORIGIN' =>  'http://localhost' (length=16)
'HTTP_UPGRADE_INSECURE_REQUESTS' =>  '1' (length=1)
'HTTP_USER_AGENT' =>  'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.221 Safari/537.36 SE 2.X MetaSr 1.0' (length=127)
省略......

$url = 'http://'.$_SERVER['HTTP_HOST'].连接后续参数