PHP调用大学成绩接口后阿拉伯字符显示为问号的求助

问题背景 #

我需要搭建页面从大学服务器获取考试成绩：

• 最初的表单直接提交到大学服务器（https://exam.albaath-univ.edu.sy/exam-med/re.php），能正常显示包含阿拉伯姓名的成绩。
• 改成用PHP cURL转发请求后，返回的阿拉伯姓名全部显示为问号，尝试过UTF-8与Windows-1256的编码转换，均无效。

原表单HTML代码：

<form action="https://exam.albaath-univ.edu.sy/exam-med/re.php" method="post" accept-charset="UTF-8">
  <p style="text-align: center;">
    <input name="number1" type="hidden" value="" />
    <input name="nospy" type="hidden" value="" />
  </p>
  <table>
    <tbody>
      <tr>
        <td>choose field</td>
        <td>
          <select name="nospy">
            <option value="1">Med</option>
          </select>
        </td>
      </tr>
      <tr>
        <td>enter your number</td>
        <td style="text-align: right;"><input name="number1" size="20" type="text" /></td>
      </tr>
      <tr>
        <td colspan="2" align="center"><input type="submit" value="show result" /></td>
      </tr>
    </tbody>
  </table>
</form>

原PHP转发代码（存在编码问题）：

<?php
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $nospy = $_POST['nospy'];
    $number1 = $_POST['number1'];

    // send the information to another PHP page using cURL
    $url = 'https://example.com/other_page.php';
    $post_data = array(
        'nospy' => $nospy,
        'number1' => $number1
    );

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $response = curl_exec($ch);
    curl_close($ch);

    // process the response from the other PHP page
    // convert it to the Windows-1256 encoding
    $response = iconv("UTF-8", "Windows-1256", $response);

    // display the converted response in HTML
    echo $response;
}
?>

解决方案 #

1. 确认服务器返回的实际编码 #

不要凭经验假设编码，先通过cURL获取响应头里的字符集信息：

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://exam.albaath-univ.edu.sy/exam-med/re.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, true); // 包含响应头
$response = curl_exec($ch);
curl_close($ch);

// 分离响应头和内容
list($header, $content) = explode("\r\n\r\n", $response, 2);
// 提取字符集
preg_match('/Content-Type:.*charset=([^\s;]+)/i', $header, $matches);
$source_charset = isset($matches[1]) ? $matches[1] : 'Windows-1256';

2. 强制设置页面输出编码 #

在PHP代码最开头设置输出的Content-Type头（必须在任何输出之前）：

// 推荐用UTF-8作为页面编码
header('Content-Type: text/html; charset=UTF-8');

3. 修正编码转换逻辑 #

根据服务器返回的编码，将内容转换为页面输出编码：

• 如果服务器返回Windows-1256，转成UTF-8：

// 优先使用mb_convert_encoding（需确保PHP开启mbstring扩展）
if (function_exists('mb_convert_encoding')) {
    $content = mb_convert_encoding($content, 'UTF-8', $source_charset);
} else {
    $content = iconv($source_charset, 'UTF-8//IGNORE', $content);
}

• 如果服务器返回UTF-8，直接输出即可，无需转换。

4. 优化cURL请求头 #

添加Accept-Charset头，引导服务器返回指定编码：

curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Accept-Charset: UTF-8, Windows-1256'
));

5. 修正后的完整PHP代码 #

<?php
// 设置页面输出编码为UTF-8，必须在任何输出之前调用
header('Content-Type: text/html; charset=UTF-8');

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $nospy = $_POST['nospy'];
    $number1 = $_POST['number1'];

    // 直接请求大学服务器，而非中转页面
    $url = 'https://exam.albaath-univ.edu.sy/exam-med/re.php';
    $post_data = array(
        'nospy' => $nospy,
        'number1' => $number1
    );

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, true);
    // 添加Accept-Charset请求头
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
        'Accept-Charset: UTF-8, Windows-1256'
    ));
    $response = curl_exec($ch);
    curl_close($ch);

    // 分离响应头与内容
    list($header, $content) = explode("\r\n\r\n", $response, 2);

    // 获取服务器返回的字符集
    preg_match('/Content-Type:.*charset=([^\s;]+)/i', $header, $matches);
    $source_charset = isset($matches[1]) ? $matches[1] : 'Windows-1256';

    // 转换编码为UTF-8
    if (strtolower($source_charset) !== 'utf-8') {
        if (function_exists('mb_convert_encoding')) {
            $content = mb_convert_encoding($content, 'UTF-8', $source_charset);
        } else {
            $content = iconv($source_charset, 'UTF-8//IGNORE', $content);
        }
    }

    // 输出处理后的内容
    echo $content;
}
?>

内容的提问来源于stack exchange，提问作者Mohammed Othman