PHP实现代理服务功能

<?php
$apiUrls = array(
     '/users' => 'https://api.example.com/users',
     '/books' => 'https://api.example.com/books',
);

$url = $apiUrls[$_SERVER['REQUEST_URI']];

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, true);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $_SERVER['REQUEST_METHOD']);

$headers = array();
foreach (getallheaders() as $name => $value) {
    $headers[] = "$name: $value";
}

if ($_SERVER['REQUEST_METHOD'] == 'POST' || $_SERVER['REQUEST_METHOD'] == 'PUT') {
    curl_setopt($ch, CURLOPT_POSTFIELDS, file_get_contents('php://input'));
    $headers[] = 'Content-Length: ' . strlen(file_get_contents('php://input'));
}

curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$response = curl_exec($ch);

if ($response === false) {
    http_response_code(500);
    echo 'Failed to proxy request';
    exit;
}

$header_size = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
$headers = substr($response, 0, $header_size);
$body = substr($response, $header_size);

foreach (explode("
", $headers) as $header) {
    header($header);
}

echo $body;