在页面刷新时，它发送curl n + 1次

Question

$headers = array (
'Authorization: key=' . 'XXXXXXXXXXXXXXXXXXXXXXXXXXXX',
'Content-Type: application/json'
);

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, 'https://android.googleapis.com/gcm/send');

curl_setopt($ch, CURLOPT_POST, true);

curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));

$result = curl_exec($ch);

curl_close($ch);

echo $result;

在页面刷新时，它会发送信息，但在每次刷新时都会发送信息 2次，3次，4次，..... 我尝试添加“Cache-Control：no-cache”，但它没有用。