用PHP获取虾米音乐网的下载链接

做链接转换的时候遇到的。虾米的链接解密有点烦，解法是我看别人的源码得到的。然后我把他改写成了PHP的版本。贴出来，有需要的就拿去用~

$mp3_id = '';//音乐ID

function unescape($str) {

    $str = rawurldecode($str);

    preg_match_all("/(?:%u.{4}).{4};\d+;.+/U",$str,$r);

    $ar = $r[0];

    foreach($ar as $k=>$v) {

        if(substr($v,0,2) == "%u")

        {

            $ar[$k] = iconv("UCS-2","utf-8//IGNORE",pack("H4",substr($v,-4)));

        }

        elseif(substr($v,0,3) == "")

        {

            $ar[$k] = iconv("UCS-2","utf-8",pack("H4",substr($v,3,-1)));

        }

        elseif(substr($v,0,2) == "")

        {

            echo substr($v,2,-1)."";

            $ar[$k] = iconv("UCS-2","utf-8",pack("n",substr($v,2,-1)));

        }

    }

    return join("",$ar);

}

$x_url="http://www.xiami.com/song/playlist/id/".$mp3_id."/object_name/default/object_id/0";

$x_con=file_get_contents($x_url);

preg_match_all( "/<location>(.*?)<\/location>/s",$x_con, $locations);

$str=$locations[1][0];

$num=substr($str, 0,1);

$inp=substr($str,1);

$iLe=strlen($inp)%$num;

$a=0;

$ret='';

$arr=array();

for ($i=0; $i<$num; $i++) {

    $arr [$i] = ($iLe>$i?1:0) + (strlen($inp)-$iLe)/$num;

}

for ($i=0; $i<$arr[1]; $i++)

    {

        $a=0;

        for ($j=0; $j<$num; $j++)

        {

            $ret .= substr($inp, $a+$i,1);

            $a += $arr[$j];

        }

}

$ret_url=unescape($ret);

$url=str_replace('^', '0', $ret_url);

$url=str_replace('+', ' ', $url);

$url=preg_replace('/.mp(.*)/', '.mp3', $url);

echo $url;