读取和base64编码二进制文件

2 回答

• 2

  和谷歌一起救援 . 我找到了以下代码，它将输入数据作为"bytes"的普通数组（0到255之间的数字，包括在内;如果 Uint8Array 直接传递给它，也可以正常工作），并将其添加到我正在使用的库中：

  //note:  it is assumed that the Base64 object has already been defined
  //License:  Apache 2.0
  Base64.byteToCharMap_ = null;
  Base64.charToByteMap_ = null;
  Base64.byteToCharMapWebSafe_ = null;
  Base64.charToByteMapWebSafe_ = null;
  Base64.ENCODED_VALS_BASE =
      'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
      'abcdefghijklmnopqrstuvwxyz' +
      '0123456789';
  
  /**
   * Our default alphabet. Value 64 (=) is special; it means "nothing."
   * @type {string}
   */
  Base64.ENCODED_VALS = Base64.ENCODED_VALS_BASE + '+/=';
  Base64.ENCODED_VALS_WEBSAFE = Base64.ENCODED_VALS_BASE + '-_.';
  
  /**
   * Base64-encode an array of bytes.
   *
   * @param {Array.<number>|Uint8Array} input An array of bytes (numbers with
   *     value in [0, 255]) to encode.
   * @param {boolean=} opt_webSafe Boolean indicating we should use the
   *     alternative alphabet.
   * @return {string} The base64 encoded string.
   */
  Base64.encodeByteArray = function(input, opt_webSafe) {
    Base64.init_();
  
    var byteToCharMap = opt_webSafe ?
                        Base64.byteToCharMapWebSafe_ :
                        Base64.byteToCharMap_;
  
    var output = [];
  
    for (var i = 0; i < input.length; i += 3) {
      var byte1 = input[i];
      var haveByte2 = i + 1 < input.length;
      var byte2 = haveByte2 ? input[i + 1] : 0;
      var haveByte3 = i + 2 < input.length;
      var byte3 = haveByte3 ? input[i + 2] : 0;
  
      var outByte1 = byte1 >> 2;
      var outByte2 = ((byte1 & 0x03) << 4) | (byte2 >> 4);
      var outByte3 = ((byte2 & 0x0F) << 2) | (byte3 >> 6);
      var outByte4 = byte3 & 0x3F;
  
      if (!haveByte3) {
        outByte4 = 64;
  
        if (!haveByte2) {
          outByte3 = 64;
        }
      }
  
      output.push(byteToCharMap[outByte1],
                  byteToCharMap[outByte2],
                  byteToCharMap[outByte3],
                  byteToCharMap[outByte4]);
    }
  
    return output.join('');
  };
  
  /**
   * Lazy static initialization function. Called before
   * accessing any of the static map variables.
   * @private
   */
  Base64.init_ = function() {
    if (!Base64.byteToCharMap_) {
      Base64.byteToCharMap_ = {};
      Base64.charToByteMap_ = {};
      Base64.byteToCharMapWebSafe_ = {};
      Base64.charToByteMapWebSafe_ = {};
  
      // We want quick mappings back and forth, so we precompute two maps.
      for (var i = 0; i < Base64.ENCODED_VALS.length; i++) {
        Base64.byteToCharMap_[i] =
            Base64.ENCODED_VALS.charAt(i);
        Base64.charToByteMap_[Base64.byteToCharMap_[i]] = i;
        Base64.byteToCharMapWebSafe_[i] =
            Base64.ENCODED_VALS_WEBSAFE.charAt(i);
        Base64.charToByteMapWebSafe_[
            Base64.byteToCharMapWebSafe_[i]] = i;
      }
    }
  };
  

  包含上述函数的库的完整代码是available here，但在其未修改的形式中，它似乎依赖于许多其他库 . 上面稍微被黑客攻击的版本应该适用于只需要快速解决此问题的任何人 .

  回复于 2024-04-19T08:35:41+08:00
• 8

  将二进制视为arraybuffer，这与任何字符编码无关 . 您的蓝色方块（.jpg）有361个本机字节，表示从0..255（十进制）的八位字节，它们不是字符！

  这意味着：使用ArrayBuffer将其编码为具有众所周知的base64算法的Base64 .

  随着Perl回归原点，显示如上所示的蓝色方块：

  my $fh = IO::File->new;
  $fh->open("d:/tmp/x.jpg", O_BINARY|O_CREAT|O_RDWR|O_TRUNC) or die $!;
  
  $fh->print(decode_base64("/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBD
  AQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCABkAGQDASIAAhEBAxEB/8QAFQABAQAA
  AAAAAAAAAAAAAAAAAAf/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFgEBAQEAAAAAAAAAAAAAAAAAAAUH/8QAFBEBAAAAAAAAAAAAAAAAAAAAAP/aAAwDAQACEQMR
  AD8AjgDcUwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAB//2Q==
  "));
  
  
  $fh->close;
  

  回复于 2024-04-19T08:35:41+08:00