使用PHP如何将普通url下载地址与迅雷下载地址thunder://相互转换

<?php
function ThunderEncode($url) {
 $thunderPrefix="AA";
 $thunderPosix="ZZ";
 $thunderTitle="thunder://";
 $thunderUrl=$thunderTitle.base64_encode($thunderPrefix.$url.$thunderPosix);
 return $thunderUrl;
}
?>

<?php
function ThunderDecode($thunderUrl) {
    $thunderPrefix="AA";
    $thunderPosix="ZZ";
    $thunderTitle="thunder://";
    $url=substr(trim($thunderUrl),10);
    $url=base64_decode($url);
    $url=substr($url,2,-2);
    return $url;
}
?>