在Python中将base64数据解码为数组

Question

我使用这个方便的Javascript函数来解码一个base64字符串，并返回一个数组。

这是字符串：

base64_decode_array('6gAAAOsAAADsAAAACAEAAAkBAAAKAQAAJgEAACcBAAAoAQAA')

下面是返回的内容：

234,0,0,0,235,0,0,0,236,0,0,0,8,1,0,0,9,1,0,0,10,1,0,0,38,1,0,0,39,1,0,0,40,1,0,0

问题是我并不真正理解javascript函数：

var base64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'.split("");
var base64inv = {}; 
for (var i = 0; i < base64chars.length; i++) { 
  base64inv[base64chars[i]] = i; 
}
function base64_decode_array (s)
{
  // remove/ignore any characters not in the base64 characters list
  //  or the pad character -- particularly newlines
  s = s.replace(new RegExp('[^'+base64chars.join("")+'=]', 'g'), "");

  // replace any incoming padding with a zero pad (the 'A' character is zero)
  var p = (s.charAt(s.length-1) == '=' ? 
          (s.charAt(s.length-2) == '=' ? 'AA' : 'A') : ""); 

  var r = [];

  s = s.substr(0, s.length - p.length) + p;

  // increment over the length of this encrypted string, four characters at a time
  for (var c = 0; c < s.length; c += 4) {

    // each of these four characters represents a 6-bit index in the base64 characters list
    //  which, when concatenated, will give the 24-bit number for the original 3 characters
    var n = (base64inv[s.charAt(c)] << 18) + (base64inv[s.charAt(c+1)] << 12) +
            (base64inv[s.charAt(c+2)] << 6) + base64inv[s.charAt(c+3)];


    // split the 24-bit number into the original three 8-bit (ASCII) characters
    r.push((n >>> 16) & 255);
    r.push((n >>> 8) & 255);
    r.push(n & 255);


  }
   // remove any zero pad that was added to make this a multiple of 24 bits
  return r;
}

"<<<“和">>>”字符的作用是什么。或者，Python有类似这样的函数吗？

Answer 1

谁在乎呢。Python有更简单的方法来做同样的事情。

[ord(c) for c in '6gAAAOsAAADsAAAACAEAAAkBAAAKAQAAJgEAACcBAAAoAQAA'.decode('base64')]

Answer 2

在Python中，我希望您只使用base64 module...

..。但是在回答你关于<<和>>>的问题时

• <<是左移位运算符；结果是第一个操作数左移第二个操作数位数；例如，10100.
• >>>是非符号扩展的右移位运算符，5 << 2是20，因为5是二进制101；结果是第一个操作数右移了第二个操作数位数...最左边的位总是用0填充。

Answer 3

为什么不干脆：

from binascii import a2b_base64, b2a_base64
encoded_data = b2a_base64(some_string)
decoded_string = a2b_base64(encoded_data)

def base64_decode_array(string):
    return [ord(c) for c in a2b_base64(string)]