高级技巧：PHP 异步 HTTP 下载多个文件的开发经验分享

<?php
// 创建cURL多个句柄数组
$curlHandles = array();

// 创建多个下载请求
$urls = array(
    "http://example.com/file1",
    "http://example.com/file2",
    "http://example.com/file3"
);
foreach ($urls as $url) {
    $handle = curl_init($url);
    curl_setopt($handle, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($handle, CURLOPT_WRITEFUNCTION, function($handle, $data) {
        // 处理下载数据
        // ...
        return strlen($data);
    });
    $curlHandles[] = $handle;
}

// 初始化多个cURL批处理句柄
$mh = curl_multi_init();

// 添加多个cURL句柄到批处理句柄中
foreach ($curlHandles as $handle) {
    curl_multi_add_handle($mh, $handle);
}

// 执行多个下载请求
$runningHandles = null;
do {
    $status = curl_multi_exec($mh, $runningHandles);
} while ($status === CURLM_CALL_MULTI_PERFORM || $runningHandles);

// 关闭多个cURL句柄
foreach ($curlHandles as $handle) {
    curl_multi_remove_handle($mh, $handle);
    curl_close($handle);
}

// 关闭cURL批处理句柄
curl_multi_close($mh);