将int，bigint整型数值可逆转换字符串

将 Int 和 BigInt 类型数值转换为字符串的可逆方法，可用于缩短网址或记录的ID转换等。
如： 9223372036854775807 => aZl8N0y58M7

class Convert {
    /** * 默认密钥字符串 * @var string */
    const KEY = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

    /** * 将 Int 类型十进制数值转换为指定进制编码 * @param int|string $num 取值范围 0 ~ 2147483647 之间 * @return string */
    public static function encodeInt($num) {
        $str = '';
        if ($num <= 0)
            $str = substr(self::KEY, 0, 1);
        while ($num > 0) {
            $val = intval($num / 62);
            $mod = $num % 62;
            $str = substr(self::KEY, $mod, 1) . $str;
            $num = $val;
        }
        return $str;
    }

    /** * 将编码字符串转换为 Int 类整型数值 * @param string $code * @return int */
    public static function decodeInt($code){
        $result = null;
        $len = strlen($code);
        for ($i = 1; $i <= $len; $i++) {
            $char = substr($code, $i - 1, 1);
            $result += intval(strpos(self::KEY, $char)) * pow(62, $len - $i);
        }
        return $result;
    }

    /** * 支持15位长度的整型，超过则精度大幅降低 * @param int $num * @return string */
    public static function encodeInt2($num) {
        $out = '';
        for ($t = floor(log10($num)/log10(62)); $t >= 0; $t--) {
            $a = floor($num/bcpow(62, $t));
            $out = $out . substr(self::KEY, $a, 1);
            $num = $num - $a * pow(62, $t);
        }
        return $out;
    }

    /** * 支持最大15位整型字符串的解码 * @param string $num * @return string */
    public static function decodeInt2($num) {
        $out = 0;
        $len = strlen($num) - 1;
        for ($t = 0; $t <= $len; $t++) {
            $out = $out + strpos(self::KEY, substr( $num, $t, 1 )) * pow(62, $len - $t);
        }
        return $out;
    }

    /** * 将 BigInt 类型的数值转换为指定进制值 * @param int|string $num * @return string */
    public static function encodeBigInt($num) {
        bcscale(0);
        $str = '';
        if ($num <= 0)
            $str = substr(self::KEY, 0, 1);
        while ($num > 0) {
            $div = bcdiv($num, 62);
            $mod = bcmod($num, 62);
            $str = substr(self::KEY, $mod, 1) . $str;
            $num = $div;
        }
        return $str;
    }

    /** * 将编码字符串转换为 BigInt 类整型数值 * @param string $code * @return string */
    public static function decodeBigInt($code) {
        bcscale(0);
        $result = '';
        $len = strlen($code);
        for ($i = 1; $i <= $len; $i++) {
            $char = substr($code, $i - 1, 1);
            $result = bcadd(bcmul(strpos(self::KEY, $char), bcpow(62, $len - $i)), $result);
        }
        return $result;
    }
}

测试方法：

结果：

echo 'Begin ~~<br><hr><br>';
$begin = microtime(true);
$bm = memory_get_usage();

$j = 0;
$cv = new Convert();
//for ($i = 0; $i < 10000; $i++) {
    $raw = '9223372036854775807';//rand(200000, 214748) . rand(1000, 3648);
    $encode = $cv->encodeBigInt($raw);
    $decode = $cv->decodeBigInt($encode);
//    $encode = $is->encodeInt($raw);
//    $decode = number_format($is->decodeInt($encode), 0, '', '');
    if ($raw != $decode) {
        $j++;
//        echo '<script>alert("not same");</script>';
    }
//}
    echo '原文: '. $raw .' 长度: '. strlen($raw) .'<br>';
    echo '编码: '. $encode .' 长度: '. strlen($encode) .'<br>';
    echo '解码: '. $decode .'<br>';
echo '不一致：'. $j;
echo '<br>';

$em = memory_get_usage();

echo 'End !<br><hr><br>Use Time :';
echo microtime(true) - $begin;
echo '<br><hr><br>Use Mem:';
echo ceil(($em - $bm)/1024/1024) .'MB';