用PHP获取虾米音乐网的下载链接

<?php
$mp3_id = '';//音乐ID
function unescape($str) {
    $str = rawurldecode($str);
    preg_match_all("/(?:%u.{4})|.{4};|&#d+;|.+/U",$str,$r);
    $ar = $r[0];
    foreach($ar as $k=&gt;$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; $i&lt;$num; $i++) {
    $arr [$i] = ($iLe&gt;$i?1:0) + (strlen($inp)-$iLe)/$num;
}
for ($i=0; $i&lt;$arr[1]; $i++)
    {
        $a=0;
        for ($j=0; $j&lt;$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;