比如 http://www.baidu.com/s?wd=%BF%EC%C0%D6&rsv_bp=0&rsv_spt=3&inputT=969 提取到http://www.baidu.com
http://top.baidu.com/s?wd=%BF%EC%C0%D6&rsv_bp=0&rsv_spt=3&inputT=969 提取到http://top.baidu.com
http://top.baidu.com/s?wd=%BF%EC%C0%D6&rsv_bp=0&rsv_spt=3&inputT=969 提取到http://top.baidu.com
//php内置了方法
$arr = parse_url('http://www.baidu.com/s?wd=%BF%EC%C0%D6&rsv_bp=0&rsv_spt=3&inputT=969');
print_r($arr);
//也可以用正则
$str = 'http://www.baidu.com/s?wd=%BF%EC%C0%D6&rsv_bp=0&rsv_spt=3&inputT=969';
preg_match_all('#https?://[^/]+#is', $str, $matches);
print_r($matches[0]);
echo pathinfo($str,PATHINFO_DIRNAME); //返回dirname