JS实现Base64加解密

var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";var base64DecodeChars = new Array(    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,    -1,  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, -1, -1, -1, -1, -1,    -1, 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, -1, -1, -1, -1);/** * BASE64 加密 */function base64encode(text) {if(typeof(text) == undefined || text ==null || text ==""){return "";}text = UTF16To8(text);    var out, i, len;    var c1, c2, c3;    len = text.length;    i = 0;    out = "";while(i < len) {    c1 = text.charCodeAt(i++) & 0xff;    if(i == len){    out += base64EncodeChars.charAt(c1 >> 2);    out += base64EncodeChars.charAt((c1 & 0x3) << 4);    out += "==";    break;    }        c2 = text.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 = text.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 */function base64decode(text) {    var c1, c2, c3, c4;    var i, len, out;    len = text.length;    i = 0;    out = "";while(i < len) {do {c1 = base64DecodeChars[text.charCodeAt(i++) & 0xff];} while(i < len && c1 == -1);if(c1 == -1) break;do {c2 = base64DecodeChars[text.charCodeAt(i++) & 0xff];} while(i < len && c2 == -1);if(c2 == -1) break;out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));do {c3 = text.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));do {c4 = text.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);    }out = UTF8To16(out);    return out;}/** * 解决Base64加密中文字符错误的问题 */function UTF16To8(text) {    var out = "";    for(var i = 0; i < text.length; i++) {    var c = text.charCodeAt(i);    if ((c >= 0x0001) && (c <= 0x007F)) {    out += text.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;}/** * 解决Base64解密中文字符错误的问题 */function UTF8To16(text) {if (!text) {return;}var i, codes, bytes, out = [],len = text.length;for (i = 0; i < len; i++) {codes = [];codes.push(text.charCodeAt(i));if (((codes[0] >> 7) & 0xff) == 0x0) {//单字节  0xxxxxxx  out.push(text.charAt(i));} else if (((codes[0] >> 5) & 0xff) == 0x6) {//双字节  110xxxxx 10xxxxxx  codes.push(text.charCodeAt(++i));bytes = [];bytes.push(codes[0] & 0x1f);bytes.push(codes[1] & 0x3f);out.push(String.fromCharCode((bytes[0] << 6) | bytes[1]));} else if (((codes[0] >> 4) & 0xff) == 0xe) {//三字节  1110xxxx 10xxxxxx 10xxxxxx  codes.push(text.charCodeAt(++i));codes.push(text.charCodeAt(++i));bytes = [];bytes.push((codes[0] << 4) | ((codes[1] >> 2) & 0xf));bytes.push(((codes[1] & 0x3) << 6) | (codes[2] & 0x3f));out.push(String.fromCharCode((bytes[0] << 8) | bytes[1]));}}return out.join('');}