从网上找的php获取头部信息的方法，支持apache和nginx环境

//获取头部信息

function em_getallheaders()
    {
        foreach ($_SERVER as $name => $value)
        {
            if (substr($name, 0, 5) == 'HTTP_')
            {
                $headers[str_replace(' ', '-', ucwords(strtolower(str_replace('_', ' ', substr($name, 5)))))] = $value;
            }
        }
        return $headers;
    }