JS 实现BASE64_ENCODE和BASE64_DECODE(实例代码)
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。三个字节有24个比特,对应于4个Base64单元,即3个字节需要用4个可打印字符来表示。它可用来作为电子邮件的传输编码。在Base64中的可打印字符包括字母A-Z、a-z、数字0-9 ,这样共有62个字符,此外两个可打印符号在不同的系统中而不同(本类库里面用的是`+`,`/`这两个字符)。一些如uuencode的其他编码方法,和之后binhex的版本使用不同的64字符集来代表6个二进制数字,但是它们不叫Base64。 实现代码一、测试可以用 var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; var base64DecodeChars = new Array(-1, -1, 62, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1); /** * base64编码 * @param {Object} str */ function base64encode(str){ var out, i, len; var c1, c2, c3; len = str.length; i = 0; out = ""; while (i < len) { c1 = str.charCodeAt(i++) & 0xff; if (i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt((c1 & 0x3) << 4); out += "=="; break; } c2 = str.charCodeAt(i++); if (i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4)); out += base64EncodeChars.charAt((c2 & 0xF) << 2); out += "="; break; } c3 = str.charCodeAt(i++); out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4)); out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6)); out += base64EncodeChars.charAt(c3 & 0x3F); } return out; } /** * base64解码 * @param {Object} str */ function base64decode(str){ var c1, c3, c4; var i, len, out; len = str.length; i = 0; out = ""; while (i < len) { /* c1 */ do { c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff]; } while (i < len && c1 == -1); if (c1 == -1) break; /* c2 */ do { c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff]; } while (i < len && c2 == -1); if (c2 == -1) break; out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4)); /* c3 */ do { c3 = str.charCodeAt(i++) & 0xff; if (c3 == 61) return out; c3 = base64DecodeChars[c3]; } while (i < len && c3 == -1); if (c3 == -1) break; out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2)); /* c4 */ do { c4 = str.charCodeAt(i++) & 0xff; if (c4 == 61) return out; c4 = base64DecodeChars[c4]; } while (i < len && c4 == -1); if (c4 == -1) break; out += String.fromCharCode(((c3 & 0x03) << 6) | c4); } return out; } /** * utf16转utf8 * @param {Object} str */ function utf16to8(str){ var out, c; out = ""; len = str.length; for (i = 0; i < len; i++) { c = str.charCodeAt(i); if ((c >= 0x0001) && (c <= 0x007F)) { out += str.charAt(i); } else if (c > 0x07FF) { out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F)); out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } else { out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } } return out; } /** * utf8转utf16 * @param {Object} str */ function utf8to16(str){ var out, c; var char2, char3; out = ""; len = str.length; i = 0; while (i < len) { c = str.charCodeAt(i++); switch (c >> 4) { case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: // 0xxxxxxx out += str.charAt(i - 1); break; case 12: case 13: // 110x xxxx 10xx xxxx char2 = str.charCodeAt(i++); out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F)); break; case 14: // 1110 xxxx10xx xxxx10xx xxxx char2 = str.charCodeAt(i++); char3 = str.charCodeAt(i++); out += String.fromCharCode(((c & 0x0F) << 12) | ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0)); break; } } return out; } //demo //function doit(){ // var f = document.f; // f.output.value = base64encode(utf16to8(f.source.value)); // f.decode.value = utf8to16(base64decode(f.output.value)); //} 功能分割版,就是将两个js函数分别写出来 Javascript的base64加密函数和base64解密函数,仿PHP base64_encode()和base64_decode().附实例。可以将js代码保存到base64.js中,在需要的时候调用。 base64加密代码 function base64_encode(str){ var c1,c2,c3; var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; var i = 0,len= str.length,string = ''; while (i < len){ c1 = str.charCodeAt(i++) & 0xff; if (i == len){ string += base64EncodeChars.charAt(c1 >> 2); string += base64EncodeChars.charAt((c1 & 0x3) << 4); string += "=="; break; } c2 = str.charCodeAt(i++); if (i == len){ string += base64EncodeChars.charAt(c1 >> 2); string += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4)); string += base64EncodeChars.charAt((c2 & 0xF) << 2); string += "="; break; } c3 = str.charCodeAt(i++); string += base64EncodeChars.charAt(c1 >> 2); string += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4)); string += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6)); string += base64EncodeChars.charAt(c3 & 0x3F) } return string } base64解密啊代码 function base64_decode(str){ var c1,c3,c4; var base64DecodeChars = new Array( -1,-1,62,63,52,53,54,55,56,57,58,59,60,61,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,-1 ); var i=0,len = str.length,string = ''; while (i < len){ do{ c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff] } while ( i < len && c1 == -1 ); if (c1 == -1) break; do{ c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff] } while ( i < len && c2 == -1 ); if (c2 == -1) break; string += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4)); do{ c3 = str.charCodeAt(i++) & 0xff; if (c3 == 61) return string; c3 = base64DecodeChars[c3] } while ( i < len && c3 == -1 ); if (c3 == -1) break; string += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2)); do{ c4 = str.charCodeAt(i++) & 0xff; if (c4 == 61) return string; c4 = base64DecodeChars[c4] } while ( i < len && c4 == -1 ); if (c4 == -1) break; string += String.fromCharCode(((c3 & 0x03) << 6) | c4) } return string; } 上面代码的测试代码 document.write(base64_encode('www.aspzz.cn')); document.write('<br />'); document.write(base64_decode('aHR0cDovL3d3dy5qYjUxLm5ldA==')); 实现代码二:针对utf8 <script language='javascript'> /* utf.js - UTF-8 <=> UTF-16 convertion * * Copyright (C) 1999 Masanao Izumo <iz@onicos.co.jp> * Version: 1.0 * LastModified: Dec 25 1999 * This library is free. You can redistribute it and/or modify it. */ /* * Interfaces: * utf8 = utf16to8(utf16); * utf16 = utf16to8(utf8); */ function utf16to8(str) { var out,i,len,c; out = ""; len = str.length; for(i = 0; i < len; i++) { c = str.charCodeAt(i); if ((c >= 0x0001) && (c <= 0x007F)) { out += str.charAt(i); } else if (c > 0x07FF) { out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F)); out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } else { out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } } return out; } function utf8to16(str) { var out,c; var char2,char3; out = ""; len = str.length; i = 0; while(i < len) { c = str.charCodeAt(i++); switch(c >> 4) { case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: // 0xxxxxxx out += str.charAt(i-1); break; case 12: case 13: // 110x xxxx 10xx xxxx char2 = str.charCodeAt(i++); out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F)); break; case 14: // 1110 xxxx 10xx xxxx 10xx xxxx char2 = str.charCodeAt(i++); char3 = str.charCodeAt(i++); out += String.fromCharCode(((c & 0x0F) << 12) | ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0)); break; } } return out; } /* Copyright (C) 1999 Masanao Izumo <iz@onicos.co.jp> * Version: 1.0 * LastModified: Dec 25 1999 * This library is free. You can redistribute it and/or modify it. */ /* * Interfaces: * b64 = base64encode(data); * data = base64decode(b64); */ var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; var base64DecodeChars = new Array( -1,-1); function base64encode(str) { var out,len; var c1,c3; len = str.length; i = 0; out = ""; while(i < len) { c1 = str.charCodeAt(i++) & 0xff; if(i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt((c1 & 0x3) << 4); out += "=="; break; } c2 = str.charCodeAt(i++); if(i == len) { out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4)); out += base64EncodeChars.charAt((c2 & 0xF) << 2); out += "="; break; } c3 = str.charCodeAt(i++); out += base64EncodeChars.charAt(c1 >> 2); out += base64EncodeChars.charAt(((c1 & 0x3)<< 4) | ((c2 & 0xF0) >> 4)); out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >>6)); out += base64EncodeChars.charAt(c3 & 0x3F); } return out; } function base64decode(str) { var c1,c4; var i,out; len = str.length; i = 0; out = ""; while(i < len) { /* c1 */ do { c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff]; } while(i < len && c1 == -1); if(c1 == -1) break; /* c2 */ do { c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff]; } while(i < len && c2 == -1); if(c2 == -1) break; out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4)); /* c3 */ do { c3 = str.charCodeAt(i++) & 0xff; if(c3 == 61) return out; c3 = base64DecodeChars[c3]; } while(i < len && c3 == -1); if(c3 == -1) break; out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2)); /* c4 */ do { c4 = str.charCodeAt(i++) & 0xff; if(c4 == 61) return out; c4 = base64DecodeChars[c4]; } while(i < len && c4 == -1); if(c4 == -1) break; out += String.fromCharCode(((c3 & 0x03) << 6) | c4); } return out; } //input base64 encode function strdecode(str){ return utf8to16(base64decode(str)); } 您可能感兴趣的文章:
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