Tips for using encode64 encoding class in php

This article mainly introduces the encoding class of PHP to implement encode64. The example analyzes the techniques of PHP to implement encode64 encoding. It has certain reference value. Friends in need can refer to it.

The example of this article tells about the implementation of encode64 in PHP. Coding class. The details are as follows:

encode64 can obtain the shortest data encoded by 26 English uppercase and lowercase letters and numbers plus the two symbols "-_". This string can be transmitted freely on the network without having to consider being automatically converted. The confusion caused by the code. Disadvantages: It is too slow for large strings. The reason is unknown. Maybe the PHP script itself is slow, so it has many built-in functions. These functions are intolerable if they are implemented in scripts. JavaScript does not have this problem. Scripts The speed is much faster.

<?PHP
//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 = &#39;PaAwO65goUf7IK2vi9-xq8cFTEXLCDY1Hd3tV0ryzjbpN_BlnSs4mGRkQWMZJeuh&#39;;
  $a = StrToBytes($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 = &#39;PaAwO65goUf7IK2vi9-xq8cFTEXLCDY1Hd3tV0ryzjbpN_BlnSs4mGRkQWMZJeuh&#39;;
  $dic = array();
  for ($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) {
 $str = &#39;&#39;;
 foreach($bytes as $ch) {
  $str .= chr($ch);
 }
 return iconv(&#39;UTF-16BE&#39;,&#39;utf-8&#39;,$str);
}
function StrToBytes($str) {
 $str = iconv(&#39;utf-8&#39;,&#39;UTF-16BE&#39;,$str);
 $len = strlen($str);
 $bytes = array();
 for($i=0;$i<$len;$i++) {
  $bytes[] = ord($str[$i]) ;
 }
 return $bytes;
}
?>

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