php json_decode null

header("Content-Type: text/html; charset=UTF-8");
$output = stripslashes(file_get_contents('http://api.car.bitauto.com/CooperationData/LieBao/priceJson.txt'));
$output = json_decode(trim($output,chr(239).chr(187).chr(191)),true);

print_r($output);

或者

header("Content-Type: text/html; charset=UTF-8");
$output = stripslashes(file_get_contents('http://api.car.bitauto.com/CooperationData/LieBao/priceJson.txt'));
$output = substr($output,3);


$output = str_replace("'", '"', $output);

var_dump(json_decode($output,false));