Js实现Base64编码与解码

湛蓝之海

Base64是一种基于64个可打印字符来表示二进制数据的表示方法。由于2的6次方等于64，所以每6个比特为一个单元，对应某个可打印字符。
Base64常用于在通常处理文本数据的场合，表示、传输、存储一些二进制数据。包括MIME的email，email via MIME, 在XML中存储复杂数据。

1.加密解密方法使用：

//1.加密 
var str = '124中文内容'; 
var base = new Base64(); 
var result = base.encode(str); 
//document.write(result); 
//2.解密 
var result2 = base.decode(result); 
document.write(result2);

2.加密、解密算法封装：

/** 
* 
* Base64 encode / decode 
* 
* @author haitao.tu 
* @date  2010-04-26 
* @email tuhaitao@foxmail.com 
* 
*/ 
function Base64() { 
  
  // private property 
  _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; 
  
  // public method for encoding 
  this.encode = function (input) { 
  var output = ""; 
  var chr1, chr2, chr3, enc1, enc2, enc3, enc4; 
  var i = 0; 
  input = _utf8_encode(input); 
  while (i < input.length) { 
    chr1 = input.charCodeAt(i++); 
    chr2 = input.charCodeAt(i++); 
    chr3 = input.charCodeAt(i++); 
    enc1 = chr1 >> 2; 
    enc2 = ((chr1 & 3) << 4) | (chr2 >> 4); 
    enc3 = ((chr2 & 15) << 2) | (chr3 >> 6); 
    enc4 = chr3 & 63; 
    if (isNaN(chr2)) { 
    enc3 = enc4 = 64; 
    } else if (isNaN(chr3)) { 
    enc4 = 64; 
    } 
    output = output + 
    _keyStr.charAt(enc1) + _keyStr.charAt(enc2) + 
    _keyStr.charAt(enc3) + _keyStr.charAt(enc4); 
  } 
  return output; 
  } 
  
  // public method for decoding 
  this.decode = function (input) { 
  var output = ""; 
  var chr1, chr2, chr3; 
  var enc1, enc2, enc3, enc4; 
  var i = 0; 
  input = input.replace(/[^A-Za-z0-9\+\/\=]/g, ""); 
  while (i < input.length) { 
    enc1 = _keyStr.indexOf(input.charAt(i++)); 
    enc2 = _keyStr.indexOf(input.charAt(i++)); 
    enc3 = _keyStr.indexOf(input.charAt(i++)); 
    enc4 = _keyStr.indexOf(input.charAt(i++)); 
    chr1 = (enc1 << 2) | (enc2 >> 4); 
    chr2 = ((enc2 & 15) << 4) | (enc3 >> 2); 
    chr3 = ((enc3 & 3) << 6) | enc4; 
    output = output + String.fromCharCode(chr1); 
    if (enc3 != 64) { 
    output = output + String.fromCharCode(chr2); 
    } 
    if (enc4 != 64) { 
    output = output + String.fromCharCode(chr3); 
    } 
  } 
  output = _utf8_decode(output); 
  return output; 
  } 
  
  // private method for UTF-8 encoding 
  _utf8_encode = function (string) { 
  string = string.replace(/\r\n/g,"\n"); 
  var utftext = ""; 
  for (var n = 0; n < string.length; n++) { 
    var c = string.charCodeAt(n); 
    if (c < 128) { 
    utftext += String.fromCharCode(c); 
    } else if((c > 127) && (c < 2048)) { 
    utftext += String.fromCharCode((c >> 6) | 192); 
    utftext += String.fromCharCode((c & 63) | 128); 
    } else { 
    utftext += String.fromCharCode((c >> 12) | 224); 
    utftext += String.fromCharCode(((c >> 6) & 63) | 128); 
    utftext += String.fromCharCode((c & 63) | 128); 
    } 
  
  } 
  return utftext; 
  } 
  
  // private method for UTF-8 decoding 
  _utf8_decode = function (utftext) { 
  var string = ""; 
  var i = 0; 
  var c = c1 = c2 = 0; 
  while ( i < utftext.length ) { 
    c = utftext.charCodeAt(i); 
    if (c < 128) { 
    string += String.fromCharCode(c); 
    i++; 
    } else if((c > 191) && (c < 224)) { 
    c2 = utftext.charCodeAt(i+1); 
    string += String.fromCharCode(((c & 31) << 6) | (c2 & 63)); 
    i += 2; 
    } else { 
    c2 = utftext.charCodeAt(i+1); 
    c3 = utftext.charCodeAt(i+2); 
    string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63)); 
    i += 3; 
    } 
  } 
  return string; 
  } 
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持CodeAE代码之家。