Js实现Base64编码与解码

前端  /  管理员 发布于 7年前   173

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 [email protected] * */ 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。