我只是从CURL返回了一个字符串，但无法获得access_token之类的值。我使用的是cakephp 4（我们使用的是debug，而不是var_dump）
cakephp中的代码（与php相同）

$AccessToken = $this->CreateAccessToken($jwt);
 $token=json_decode($AccessToken);
  debug($token);
 debug($token['access_token']);

这个字符串看起来像下面的调试，但是我不能提取值。我认为问题是json_decode不工作，所以我仍然得到字符串

/////////////////
debug($token) :        { "access_token": "Bearer exxxxxxxxxx1h7kQuxaOqB-AbaoMPh7qLgA", "expires_in": 1892160000, "api_domain": "https://xx1.xxh.com/v1", "token_type": "Bearer" }

debug($token['access_token']:Notice (8): Trying to access array offset on value of type int
/////////////

这就是上面调试的var_dump上显示的内容。我可以显示整个返回的令牌，但不能访问它里面的任何内容
下面是执行此操作的代码

private function CreateAccessToken($jwt)
{
$jwt_token = "Bearer ".$jwt;
$headers = array("content-type: application/json", "Authorization:".$jwt_token);

    $curl = curl_init();
    curl_setopt_array($curl, array(
    CURLOPT_URL => "https://xx/v1/xx/api/token",
    CURLOPT_SSL_VERIFYHOST => 0,
    CURLOPT_SSL_VERIFYPEER => 0,
    CURLOPT_FOLLOWLOCATION => true,
    CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
    CURLOPT_CUSTOMREQUEST => "POST",
    CURLOPT_HTTPHEADER => array("content-type: application/x-www-form-urlencoded"),
    CURLOPT_POSTFIELDS => http_build_query(array(
    'assertion' => $jwt_token,
    'grant_type' => 'urn:ietf:params:oauth:grant-type:jwt-bearer')),
    ));

    $response = curl_exec($curl);
    $err = curl_error($curl);
    curl_close($curl);
    if($err) 
    {
      echo "cURL Error #:" . $err;
      return 0;
    } 
    else 
    {
      return $response;
    }
}

output var_dump（$token）//仍然是int中的字符串吗？

{ "access_token": "Bearer exxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx2GB3PS5c4tq9iOvSTH7lx-7gI_JHaw", "expires_in": 1892160000, "api_domain": "https://xx.xx.com/v1", "token_type": "Bearer" }int(1)

output var_dump（$AccessToken）//仍然是bool中的字符串吗？

{ "access_token": "Bearer eyxxxxxxnx1bul67sSWM8fxFmLkJywP6UZryO9o8", "expires_in": 1892160000, "api_domain": "https://xx.xx.com/v1", "token_type": "Bearer" }bool(true)

How to extract required data from CURL response?