php获取301跳转URL简单实例

复制代码 代码如下:
/**
 * get_redirect_url()
 * Gets the address that the provided URL redirects to,
 * or FALSE if there"s no redirect.
 *
 * @param string $url
 * @return string
 */
function get_redirect_url($url){
    $redirect_url = null;     $url_parts = @parse_url($url);
    if (!$url_parts) return false;
    if (!isset($url_parts["host"])) return false; //can"t process relative URLs
    if (!isset($url_parts["path"])) $url_parts["path"] = "/";    $sock = fsockopen($url_parts["host"], (isset($url_parts["port"]) ? (int)$url_parts["port"] : 80), $errno, $errstr, 30);
    if (!$sock) return false;

    $request = "HEAD " . $url_parts["path"] . (isset($url_parts["query"]) ? "?".$url_parts["query"] : "") . " HTTP/1.1";
    $request .= "Host: " . $url_parts["host"] . "";
    $request .= "Connection: Close";
    fwrite($sock, $request);
    $response = "";
    while(!feof($sock)) $response .= fread($sock, 8192);
    fclose($sock);
    if (preg_match("/^Location: (.+?)$/m", $response, $matches)){
        if ( substr($matches[1], 0, 1) == "/" )
            return $url_parts["scheme"] . "://" . $url_parts["host"] . trim($matches[1]);
        else
            return trim($matches[1]);    } else {
        return false;
    }}
/**
 * get_all_redirects()
 * Follows and collects all redirects, in order, for the given URL.
 *
 * @param string $url
 * @return array
 */
function get_all_redirects($url){
    $redirects = array();
    while ($newurl = get_redirect_url($url)){
        if (in_array($newurl, $redirects)){
            break;
        }
        $redirects[] = $newurl;
        $url = $newurl;
    }
    return $redirects;
}
php实现用socket获取301跳转地址，可以提取跳转过程中的url