PHP+Dropbox，通过CURL返回较大缩略图的第一位来获取缩略图

<?php
// Dropbox API端点
$apiEndpoint = 'https://api.dropboxapi.com/2/files/get_thumbnail';

// 文件路径
$filePath = '/path/to/file';

// 缩略图尺寸
$thumbnailSize = 'w64h64';

// 构建API请求参数
$data = array(
    'path' => $filePath,
    'format' => 'jpeg',
    'size' => $thumbnailSize
);

// 发送API请求
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $apiEndpoint);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Authorization: Bearer YOUR_ACCESS_TOKEN',
    'Content-Type: application/json'
));

$response = curl_exec($ch);
curl_close($ch);

// 解析API响应
$responseData = json_decode($response, true);

// 提取缩略图URL的第一位字符
$thumbnailUrl = $responseData['thumbnail'];
$firstCharacter = substr($thumbnailUrl, 0, 1);

echo '缩略图的第一位字符是：' . $firstCharacter;
?>