使用cURL将文件保存到dropbox rest

Question

我试图使用php中的cURL将文件放入dropbox rest api。

https://www.dropbox.com/developers/core/docs#files_put

这是我的代码

$token = '-';

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL, "https://api-content.dropbox.com/1/files_put/auto/test.txt?overwrite=true&access_token=" . $token);
//curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Authorization: Bearer ' . $token));
curl_setopt($ch, CURLOPT_POSTFIELDS,
  http_build_query(array('postvar1' => 'value1')));

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

$server_output = curl_exec ($ch);

curl_close ($ch);
if ($server_output == "OK") {
  echo "hi";
} else {
  echo "nein";
}

但由于某些原因，这不起作用。任何帮助将不胜感激。