get_headers函数模拟版

/*
模拟php的get_headers()函数;
在sae中需要关闭CURLOPT_FOLLOWLOCATION参数，否则不会有Location;缺点是没法跟踪跳转的链接
略有不同：Content-Length: 0 不会显示;一般的处理时没有问题的
*/
function getHeaders($url,$format=0,$FOLLOWLOCATION=1){
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_HEADER, 1);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($curl, CURLOPT_TIMEOUT, 10);
    curl_setopt($curl, CURLOPT_NOBODY, 1);//不包含网页的内容
    if($FOLLOWLOCATION){
    curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);//允许链接自动跳转,当系统开启safe_mode或open_basedir,会出错,该关闭
    }
    curl_setopt($curl, CURLOPT_AUTOREFERER, 1);//自动referer
    //curl_setopt($curl, CURLOPT_MAXREDIRS, 1);//限定CURLOPT_FOLLOWLOCATION递归返回的数量        
    $header = curl_exec($curl);
    curl_close($curl);
    $back =  array_filter(explode(PHP_EOL,$header));
    //return array_filter(explode(PHP_EOL,$header));
    if($format){
        foreach($back as $val)
        {
            if(preg_match('/^([^:]+): +(.*)$/',$val,$parts))
            {
                if (array_key_exists($parts[1],$v)){
                    $v[$parts[1]] = array_merge_recursive((array)$v[$parts[1]],(array)$parts[2]);
                }
                else
                {
                    $v[$parts[1]]=$parts[2];
                }
            }
            else{
                if(isset($v[0])){
                    $v[]=$val;
                }
                else{
                    $v[0]=$val;
                }
            }
        }
        return $v;
    }
    return $back;
}