PHP调用接口用post方法传送json数据

$keyword = urlencode($_POST['keyword']);
$parameters = json_encode(array('keyWord'=>$keyword,'areaCode'=>'*'));
$post_data['appToken'] = "323ds7674354fds32fdsda60173";//随便写的
$post_data['parameters'] = $parameters;
$url = 'http://serde.com/compadddvd/index';//随便写的
$ch = curl_init();
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);//用post方法传送参数
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec($ch);
curl_close($ch);