如何读取 PHP 中的请求标头？

我应该如何读取 PHP 中的任何标头？

例如自定义标头：X-Requested-With.

IF：你只需要一个标题，而不是allheaders，最快的方法是：

<?php
// Replace XXXXXX_XXXX with the name of the header you need in UPPERCASE (and with '-' replaced by '_')
$headerStringValue = $_SERVER['HTTP_XXXXXX_XXXX'];

ELSE IF：将 PHP 作为 Apache 模块运行，或者从 PHP 5.4 开始，使用 FastCGI（简单方法）：

apache_request_headers() http://www.php.net/apache_request_headers

<?php
$headers = apache_request_headers();

foreach ($headers as $header => $value) {
    echo "$header: $value <br />\n";
}

ELSE:在任何其他情况下，您可以使用（用户态实现）：

<?php
function getRequestHeaders() {
    $headers = array();
    foreach($_SERVER as $key => $value) {
        if (substr($key, 0, 5) <> 'HTTP_') {
            continue;
        }
        $header = str_replace(' ', '-', ucwords(str_replace('_', ' ', strtolower(substr($key, 5)))));
        $headers[$header] = $value;
    }
    return $headers;
}

$headers = getRequestHeaders();

foreach ($headers as $header => $value) {
    echo "$header: $value <br />\n";
}

See Also:
getallheaders() http://php.net/manual/en/function.getallheaders.php - (PHP >= 5.4) cross platform edition Alias of apache_request_headers() apache_response_headers() http://www.php.net/manual/en/function.apache-response-headers.php - Fetch all HTTP response headers.
headers_list() http://www.php.net/manual/en/function.headers-list.php - Fetch a list of headers to be sent.