apache_request_headers()

(PHP 4 >= 4.3.0, PHP 5, PHP 7)

获取全部 HTTP 请求头信息

说明

apache_request_headers(void): array

获取当前请求的所有请求头信息

返回值

包含当前请求所有头信息的数组，失败返回FALSE。

更新日志

范例

apache_request_headers()示例

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

以上例程的输出类似于：

Accept: */*
Accept-Language: en-us
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0
Host: www.example.com
Connection: Keep-Alive

注释

Note:

你也可以试图从环境变量中读取普通CGI变量，PHP以Apache模块方式运行时有可能无法获得。使用phpinfo()获得可读取的变量列表。环境变量.

参见

• apache_response_headers()获得全部 HTTP 响应头信息

I didn't found a replacement for apache_request_headers() in PHP::Compat (http://pear.php.net/package/PHP_Compat) so I wrote my own:
<?php
if( !function_exists('apache_request_headers') ) {
///
function apache_request_headers() {
 $arh = array();
 $rx_http = '/\AHTTP_/';
 foreach($_SERVER as $key => $val) {
  if( preg_match($rx_http, $key) ) {
   $arh_key = preg_replace($rx_http, '', $key);
   $rx_matches = array();
   // do some nasty string manipulations to restore the original letter case
   // this should work in most cases
   $rx_matches = explode('_', $arh_key);
   if( count($rx_matches) > 0 and strlen($arh_key) > 2 ) {
    foreach($rx_matches as $ak_key => $ak_val) $rx_matches[$ak_key] = ucfirst($ak_val);
    $arh_key = implode('-', $rx_matches);
   }
   $arh[$arh_key] = $val;
  }
 }
 return( $arh );
}
///
}
///
?>

Superglobal $_SERVER, used in all patches for missing getallheaders() contains only truly basic headers. To pass ANY header into PHP in any httpd environment, including CGI/FCGI just add rule (any number of rules) into .htaccess:
RewriteRule .* - [E=HTTP_MY_HEADER:%{HTTP:My-Header}]
and the header with it's value will appear for PHP as 
<?php print $_SERVER['HTTP_MY_HEADER']; ?>
And... just couldn't hold off. Rewrtiting $_SERVER keys for replacing missing function really does not require RegExps, preg_matches or evals... Try this:
<?php
function getallheaders() { 
 foreach($_SERVER as $K=>$V){$a=explode('_' ,$K); 
   if(array_shift($a)=='HTTP'){ 
      array_walk($a,function(&$v){$v=ucfirst(strtolower($v));});
    $retval[join('-',$a)]=$V;} 
  } return $retval; }
 ?>

There is a simple way to get request headers from Apache even on PHP running as a CGI. As far as I know, it's the only way to get the headers "If-Modified-Since" and "If-None-Match" when apache_request_headers() isn't available. You need mod_rewrite, which most web hosts seem to have enabled. Put this in an .htacess file in your web root:
RewriteEngine on
RewriteRule .* - [E=HTTP_IF_MODIFIED_SINCE:%{HTTP:If-Modified-Since}]
RewriteRule .* - [E=HTTP_IF_NONE_MATCH:%{HTTP:If-None-Match}]
The headers are then available in PHP as
<?php
 $_SERVER['HTTP_IF_MODIFIED_SINCE'];
 $_SERVER['HTTP_IF_NONE_MATCH'];
?>
I've tested this on PHP/5.1.6, on both Apache/2.2.3/Win32 and Apache/2.0.54/Unix, and it works perfectly.
Note: if you use RewriteRules already for clean URLs, you need to put the above rules AFTER your existing ones.

Although we expect to see headers in mixed case, the standard RFC2616 demands that "field names are case-insensitive". PHP delivers the headers exactly untouched in whatever way the client sent them. Potentially you should expect to get any type of uppercase or lowercase or mixed.
Thus, if you want to be standards compliant, you must loop through every key and check it in a case-insensitive manner, instead of doing the obvious thing and using the name of the header as an array index.

A slightly modified version from limalopex.eisfux.de. Fixes the missing Headers Content-Type and Content-Length and makes it Camel-Case.
<?php
if( !function_exists('apache_request_headers') ) {
    function apache_request_headers() {
        $arh = array();
        $rx_http = '/\AHTTP_/';
        foreach($_SERVER as $key => $val) {
            if( preg_match($rx_http, $key) ) {
                $arh_key = preg_replace($rx_http, '', $key);
                $rx_matches = array();
                // do some nasty string manipulations to restore the original letter case
                // this should work in most cases
                $rx_matches = explode('_', strtolower($arh_key));
                if( count($rx_matches) > 0 and strlen($arh_key) > 2 ) {
                    foreach($rx_matches as $ak_key => $ak_val) $rx_matches[$ak_key] = ucfirst($ak_val);
                    $arh_key = implode('-', $rx_matches);
                }
                $arh[$arh_key] = $val;
            }
        }
        if(isset($_SERVER['CONTENT_TYPE'])) $arh['Content-Type'] = $_SERVER['CONTENT_TYPE'];
        if(isset($_SERVER['CONTENT_LENGTH'])) $arh['Content-Length'] = $_SERVER['CONTENT_LENGTH'];
        return( $arh );
    }
}