PHP开发中如何实现百度文心一言API的访问鉴权？

<?php
require_once('BaiduOAuth2.php');  //引入百度OAuth2类

$apiKey = 'Your_API_Key';  //替换为您在百度开放平台获取的API Key
$secretKey = 'Your_Secret_Key';  //替换为您在百度开放平台获取的Secret Key

$oauth = new BaiduOAuth2($apiKey, $secretKey);  //实例化百度OAuth2类

//获取访问令牌
$res = $oauth->getAccessToken();
if (!$res) {
    echo '获取访问令牌失败!';
    exit;
}

$accessToken = $oauth->getToken();  //获取访问令牌
$expiresIn = $oauth->getExpiresIn();  //获取访问令牌的有效期

//开始访问百度文心一言API
$url = 'https://aip.baidubce.com/rpc/2.0/unit/bot/chat';

//设置请求参数
$data = array(
    'access_token' => $accessToken,
    'query' => '你好'
);

$options = array(
    'http' => array(
        'method' => 'POST',
        'header' => 'Content-type: application/x-www-form-urlencoded',
        'content' => http_build_query($data)
    )
);

$context = stream_context_create($options);
$result = file_get_contents($url, false, $context);

//输出API调用结果
echo $result;
?>