php的encode64編碼類

encode64可以获得最短的由26个英文大小写字母数字加上"-_"两个符号编码的数据, 这个个字串可以在网络自由传输, 无需考虑被自动转码引起的混乱. 缺点: 对于大字串太慢了, 原因不明, 可能PHP脚本本身就是慢, 所以它内置 很多函数, 这些函数如果用脚本来实现是不可忍受的. 而JavaScript就没这个问题, 脚本的速度快的多.

//encode64编码可以同时取代encodeURI,encodeURIComponent,endode函数, 因为选取的这些字符都不会被编码.
class Encode64{
    function code($str) {
        $KEY = 'PaAwO65goUf7IK2vi9-xq8cFTEXLCDY1Hd3tV0ryzjbpN_BlnSs4mGRkQWMZJeuh';
        $a = StrToBytes($str);
        $len = count($a);
        $res = $len % 3;
        $s = "";$i = 2;$v = 0;
        for (; $i < $len; $i  = 3) {
            $v = $a[$i - 2]   ($a[$i - 1] << 8)   ($a[$i] << 16);
            $s .= $KEY[$v & 0x3f];
            $s .= $KEY[($v >> 6) & 0x3f];
            $s .= $KEY[($v >> 12) & 0x3f];
            $s .= $KEY[($v >> 18)];
        }
        if ($res == 1) {
            $v = $a[$i - 2];
            $s .= $KEY[$v & 0x3f];
            $s .= $KEY[($v >> 6) & 0x3f];
        } else if ($res == 2) {
            $v = $a[$i - 2]   ($a[$i - 1] << 8);
            $s .= $KEY[$v & 0x3f];
            $s .= $KEY[($v >> 6) & 0x3f];
            $s .= $KEY[($v >> 12) & 0x3f];
        }
        return $s;
    }
    function decode($codeStr) {
        $KEY = 'PaAwO65goUf7IK2vi9-xq8cFTEXLCDY1Hd3tV0ryzjbpN_BlnSs4mGRkQWMZJeuh';
        $dic = array();
        for ($i = 0; $i < 64; $i  ) {
            $dic[$KEY[$i]] = $i;
        }
        $len = strlen($codeStr);
        $res = $len % 4;
        $cLen = floor($len/4)*3;
        if($res==2) $clen  = 1;
        elseif($res==3) $clen  = 2;
        $code = range(0,$clen);
        $i = 3;$v = 0; $j = 0;
        for (; $i < $len; $i  = 4) {
            $v = $dic[$codeStr[$i - 3]];
            $v  = $dic[$codeStr[$i - 2]] << 6;
            $v  = $dic[$codeStr[$i - 1]] << 12;
            $v  = $dic[$codeStr[$i]] << 18;
            $code[$j] = $v & 0xff;
            $code[$j 1] = ($v >> 8) & 0xff;
            $code[$j 2] = ($v >> 16) & 0xff;
            $j  = 3;
        }
        if ($res == 2) {//正确的字节数肯定是余2或3, 没有1的情况, 如果出现, 舍弃.
            $v = $dic[$codeStr[$i - 3]];
            $v  = $dic[$codeStr[$i - 2]] << 6;
            $code[$j] = $v & 0xff;
        } else if ($res == 3) {
            $v = $dic[$codeStr[$i - 3]];
            $v  = $dic[$codeStr[$i - 2]] << 6;
            $v  = $dic[$codeStr[$i - 1]] << 12;
            $code[$j] = $v & 0xff;
            $code[$j 1] = ($v >> 8) & 0xff;
        }
        return BytesToStr($code);
    }
}
function BytesToStr($bytes) {
    $str = '';
    foreach($bytes as $ch) {
        $str .= chr($ch);
    }
    return iconv('UTF-16BE','utf-8',$str);
}
function StrToBytes($str) {
    $str = iconv('utf-8','UTF-16BE',$str);
    $len = strlen($str);
    $bytes = array();
    for($i=0;$i<$len;$i  ) {
        $bytes[] =  ord($str[$i]) ;
    }
    return $bytes;
}
?>

php