将市面上的base64方法改写为typescript类 需要的拿走不谢
代码语言：javascript复制export class Base64 {
// private property
private _keyStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 /=';
// public method for encoding
encode(input) {
let output = '';
let chr1, chr2, chr3, enc1, enc2, enc3, enc4;
let i = 0;
input = this._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
this._keyStr.charAt(enc1) this._keyStr.charAt(enc2)
this._keyStr.charAt(enc3) this._keyStr.charAt(enc4);
}
return output;
}
// public method for decoding
decode(input) {
let output = '';
let chr1, chr2, chr3;
let enc1, enc2, enc3, enc4;
let i = 0;
input = input.replace(/[^A-Za-z0-9 /=]/g, '');
while (i < input.length) {
enc1 = this._keyStr.indexOf(input.charAt(i ));
enc2 = this._keyStr.indexOf(input.charAt(i ));
enc3 = this._keyStr.indexOf(input.charAt(i ));
enc4 = this._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 = this._utf8_decode(output);
return output;
}
// private method for UTF-8 encoding
private _utf8_encode(string) {
string = string.replace(/rn/g, 'n');
let utftext = '';
for (let n = 0; n < string.length; n ) {
const 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
private _utf8_decode(utftext) {
let string = '';
let i = 0;
let c = 0, c2 = 0, c3 = 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;
}
}
