$timestamp = $_GET['timestamp'];
$nonce = $_GET["nonce"];
$msg_signature = $_GET['msg_signature'];
$encrypt_type = $_GET['encrypt_type'];
$openid=$_GET['openid'];
$xmldata =file_get_contents('php://input' );//The packet capture shows that there is data, but it cannot be obtained. Ask God.
It seems that the JSON data that comes back is just json_decode
It seems we need json_decode