解析php 版获取重定向后的地址(代码)

代码如下:
//取重定向的地址
class RedirectUrl{
//地址
var $url;
//初始化地址
function RedirectUrl($url){
$this>url = $url;
}
/**
* get_redirect_url()
* 取重定向的地址
*
* @param string $url
* @return string
*/
private function get_redirect_url($url){
$redirect_url = null;

$url_parts = @parse_url($url);
if (!$url_parts) return false;
if (!isset($url_parts[host])) return false; //cant process relative URLs
if (!isset($url_parts[path])) $url_parts[path] = /;

$sock = fsockopen($url_parts[host]  (isset($url_parts[port]) ? (int)$url_parts[port] : ) $errno  $errstr );
if (!$sock) return false;

$request = "HEAD " $url_parts[path] (isset($url_parts[query])  ??$url_parts[query] : ) " HTTP/rn";
$request = Host: $url_parts[host] "rn";
$request = "Connection: Closernrn";
fwrite($sock $request);
$response = ;
while(!feof($sock)) $response = fread($sock );
fclose($sock);

if (preg_match(/^Location: (+?)$/m $response $matches)){
return trim($matches[]);
} else {
return false;
}
}

/**
* get_all_redirects()
* 取所有重定向地址
*
* @param string $url
* @return array
*/
private function get_all_redirects($url){
$redirects = array();
while ($newurl = $this>get_redirect_url($url)){
if (in_array($newurl $redirects)){
break;
}
$redirects[] = $newurl;
$url = $newurl;
}
return $redirects;
}

/**
* get_final_url()
* 取实际地址
*
* @param string $url
* @return string
*/
function get_final_url(){
$redirects = $this>get_all_redirects($this>url);

if (count($redirects)>){
return array_pop($redirects);
} else {
return $this>url;
}
}
}

/**
* get_show_pic
* 取最终要显示的图片地址
*
* @param string $url
* @return  string
*/
function get_show_pic($url$noimg =noimggif$newimg="{
$obj = new RedirectUrl($url);

$realurl = $obj>get_final_url();

if(strpos($realurl$noimg)>){
return $newimg;
}
return $url;
}
//参考
echo "<img src="get_show_pic("/>";
?>