PHP implementation steps to obtain the header information of http request

The PHP manual provides ready-made functions:
getallheaders
(PHP 4, PHP 5)
getallheaders — Fetch all HTTP request headers
Description
array getallheaders ( void )
Fetches all HTTP headers from the current request.
This function is an alias for apache_request_headers(). Please read theapache_request_headers() documentation for more information on how this function works.
Return value
An associative array of all the HTTP headers in the current request, orFALSE on failure.
Example #1 getallheaders() example

<?php 
foreach (getallheaders() as $name => $value) { 
echo "$name: $value\n"; 
} 
?>

However, this function can only be used in the apache environment, iis or nginx does not support it, it can be implemented through custom functions

<?php 
if (!function_exists(&#39;getallheaders&#39;)) 
{ 
    function getallheaders() 
    { 
       foreach ($_SERVER as $name => $value) 
       { 
           if (substr($name, 0, 5) == &#39;HTTP_&#39;) 
           { 
               $headers[str_replace(&#39; &#39;, &#39;-&#39;, ucwords(strtolower(str_replace(&#39;_&#39;, &#39; &#39;, substr($name, 5)))))] = $value; 
           } 
       } 
       return $headers; 
    } 
}
 
?>

Okay, let’s see what is printed

<?php 
print_r(getallheaders());

Get the result:

Array 
( 
[Accept] => */* 
[Accept-Language] => zh-cn 
[Accept-Encoding] => gzip, deflate 
[User-Agent] => Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727) 
[Host] => localhost 
[Connection] => Keep-Alive 
)

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