七牛云存储____七牛安全base64解析

来源：互联网发布：java初级程序员工资编辑：程序博客网时间：2024/04/30 06:43
/* * Interfaces: * b64 = base64encode(data); * data = base64decode(b64); *///安全编码的安全字符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);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;}function base64decode(str) {    var c1, c2, 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;}//对特殊字符进行了安全替换var safe64 = function(base64) {    base64 = base64.replace(/\+/g, "-");    base64 = base64.replace(/\//g, "_");    return base64;};
0 0