$post_data_string = http_build_query($post_data, '&');
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $get_session_url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$xmloutput = curl_exec($ch);
一般这样写 你自己对比下