HarmonyOS NEXT鸿蒙开发 ArkTS：Base64Helper Base64编码转码

作者：马育民 • • 阅读：10047

介绍

官方介绍

Base64Helper 类提供Base64编解码和Base64URL编解码功能。

Base64编码表包含 A-Z、a-z、0-9 这62个字符，以及 + 和 / 这两个特殊字符。在编码时，将原始数据 按3个字节 一组进行划分，得到若干个6位的数字，然后使用Base64编码表中对应的字符来表示这些数字。如果最后剩余1或2个字节，则需要使用”=”字符进行补齐。

Base64URL编码表包含 A-Z、a-z、0-9 以及 - 和 _ 64个字符，Base64URL编码结果不含 =。

导包

使用前需要导包

import { util } from '@kit.ArkTS';

构造方法

constructor()

例子

let base64 = new util.Base64Helper();

编码为 Uint8Array 对象

通过输入参数编码后输出 Uint8Array 对象

encodeSync(src: Uint8Array, options?: Type): Uint8Array

参数：

  • src：Uint8Array 类型，必填，待编码的Uint8Array对象。

  • options：Type 类型，表示对应的编码格式。此参数可选，可选值为：

    • util.Type.BASIC：表示Base64编码，默认值

    • util.Type.BASIC_URL_SAFE：表示Base64URL编码。

返回值： Uint8Array 类型，返回编码后的Uint8Array对象

例子

let base64Helper = new util.Base64Helper();
let array = new Uint8Array([115,49,51]);
let result = base64Helper.encodeSync(array);
console.info("result = " + result);
// 输出结果：result = 99,122,69,122

编码为字符串

将输入的Uint8Array字节数组进行Base64编码，返回一个字符串结果。该方法支持多种编码格式，包括标准Base64编码、MIME格式的Base64编码（带有换行符）、URL安全格式的Base64编码等。

encodeToStringSync(src: Uint8Array, options?: Type): string

参数：

  • src：Uint8Array 类型，必填待编码Uint8Array对象。

  • options：Type 类型，此参数可选，可选值为

    • 当参数取值为 util.Type.BASIC，表示Base64编码，返回值没有回车符、换行符。默认值

    • 当参数取值为 util.Type.MIME ，表示使用Base64编码。如果返回值超过76个字符，则会在每76个字符处进行换行，并以 \r\n 结束每行。如果返回值少于76个字符，则会抛出异常。

    • 当参数取值为 util.Type.BASIC_URL_SAFE ，表示Base64URL编码，返回值没有回车符、换行符。

    • 当参数取值为 util.Type.MIME_URL_SAFE ，表示Base64URL编码，返回值每一行不超过76个字符，而且每行以 \r\n 符结束。

返回值：string 类型，返回编码后的字符串。

例子

// MIME编码
let base64Helper = new util.Base64Helper();
let array =
  new Uint8Array([77, 97, 110, 105, 115, 100, 105, 115, 116, 105, 110, 103, 117, 105, 115, 104, 101, 100, 110, 111, 116,
    111, 110, 108, 121, 98, 121, 104, 105, 115, 114, 101, 97, 115, 111, 110, 98, 117, 116, 98, 121, 116, 104, 105, 115,
    115, 105, 110, 103, 117, 108, 97, 114, 112, 97, 115, 115, 105, 111, 110, 102, 114, 111, 109, 111, 116, 104, 101,
    114, 97, 110, 105, 109, 97, 108, 115, 119, 104, 105, 99, 104, 105, 115, 97, 108, 117, 115, 116, 111, 102, 116, 104,
    101, 109, 105, 110, 100, 101, 120, 99, 101, 101, 100, 115, 116, 104, 101, 115, 104, 111, 114, 116, 118, 101, 104,
    101, 109, 101, 110, 99, 101, 111, 102, 97, 110, 121, 99, 97, 114, 110, 97, 108, 112, 108, 101, 97, 115, 117, 114,
    101]);
let result = base64Helper.encodeToStringSync(array, util.Type.MIME);
console.info("result = " + result);
/*
输出结果：result = TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNz
aW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZl
aGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU=
*/

// BASIC编码
let base64Helper = new util.Base64Helper();
let array =
  new Uint8Array([77, 97, 110, 105, 115, 100, 105, 115, 116, 105, 110, 103, 117, 105, 115, 104, 101, 100, 110, 111, 116,
    111, 110, 108, 121, 98, 121, 104, 105, 115, 114, 101, 97, 115, 111, 110, 98, 117, 116, 98, 121, 116, 104, 105, 115,
    115, 105, 110, 103, 117, 108, 97, 114, 112, 97, 115, 115, 105, 111, 110, 102, 114, 111, 109, 111, 116, 104, 101,
    114, 97, 110, 105, 109, 97, 108, 115, 119, 104, 105, 99, 104, 105, 115, 97, 108, 117, 115, 116, 111, 102, 116, 104,
    101, 109, 105, 110, 100, 101, 120, 99, 101, 101, 100, 115, 116, 104, 101, 115, 104, 111, 114, 116, 118, 101, 104,
    101, 109, 101, 110, 99, 101, 111, 102, 97, 110, 121, 99, 97, 114, 110, 97, 108, 112, 108, 101, 97, 115, 117, 114,
    101]);
let result = base64Helper.encodeToStringSync(array, util.Type.BASIC);
console.info("result = " + result);
/*
输出结果：result = TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNzaW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZlaGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU=
*/

// MIME_URL_SAFE编码
let base64Helper = new util.Base64Helper();
let array =
  new Uint8Array([77, 97, 110, 105, 115, 100, 105, 115, 116, 105, 110, 103, 117, 105, 115, 104, 101, 100, 110, 111, 116,
    111, 110, 108, 121, 98, 121, 104, 105, 115, 114, 101, 97, 115, 111, 110, 98, 117, 116, 98, 121, 116, 104, 105, 115,
    115, 105, 110, 103, 117, 108, 97, 114, 112, 97, 115, 115, 105, 111, 110, 102, 114, 111, 109, 111, 116, 104, 101,
    114, 97, 110, 105, 109, 97, 108, 115, 119, 104, 105, 99, 104, 105, 115, 97, 108, 117, 115, 116, 111, 102, 116, 104,
    101, 109, 105, 110, 100, 101, 120, 99, 101, 101, 100, 115, 116, 104, 101, 115, 104, 111, 114, 116, 118, 101, 104,
    101, 109, 101, 110, 99, 101, 111, 102, 97, 110, 121, 99, 97, 114, 110, 97, 108, 112, 108, 101, 97, 115, 117, 114,
    101]);
let result = base64Helper.encodeToStringSync(array, util.Type.BASIC_URL_SAFE);
console.info("result = " + result);
/*
输出结果：result = TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNzaW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZlaGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU
*/
// MIME_URL_SAFE编码
let base64Helper = new util.Base64Helper();
let array =
  new Uint8Array([77, 97, 110, 105, 115, 100, 105, 115, 116, 105, 110, 103, 117, 105, 115, 104, 101, 100, 110, 111, 116,
    111, 110, 108, 121, 98, 121, 104, 105, 115, 114, 101, 97, 115, 111, 110, 98, 117, 116, 98, 121, 116, 104, 105, 115,
    115, 105, 110, 103, 117, 108, 97, 114, 112, 97, 115, 115, 105, 111, 110, 102, 114, 111, 109, 111, 116, 104, 101,
    114, 97, 110, 105, 109, 97, 108, 115, 119, 104, 105, 99, 104, 105, 115, 97, 108, 117, 115, 116, 111, 102, 116, 104,
    101, 109, 105, 110, 100, 101, 120, 99, 101, 101, 100, 115, 116, 104, 101, 115, 104, 111, 114, 116, 118, 101, 104,
    101, 109, 101, 110, 99, 101, 111, 102, 97, 110, 121, 99, 97, 114, 110, 97, 108, 112, 108, 101, 97, 115, 117, 114,
    101]);
let result = base64Helper.encodeToStringSync(array, util.Type.MIME_URL_SAFE);
console.info("result = " + result);
/*
输出结果：result = TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNz
aW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZl
aGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU
*/

解码

将输入参数解码后输出对应Uint8Array对象。

decodeSync(src: Uint8Array | string, options?: Type): Uint8Array

参数：

  • src：Uint8Array | string 类型，必填，待解码的Uint8Array 对象或者字符串。

  • options：Type类型，此参数可选，可选值为：

    • 当参数取值为 util.Type.BASIC，表示Base64解码。默认值

    • 当参数取值为 util.Type.MIME，表示Base64解码，src入参包含回车符、换行符。

    • 当参数取值为 util.Type.BASIC_URL_SAFE，表示Base64URL解码。

    • 当参数取值为 util.Type.MIME_URL_SAFE，表示Base64URL解码，src入参包含回车符、换行符。

返回值：Uint8Array 类型，返回解码后新分配的Uint8Array对象。

例子

let base64Helper = new util.Base64Helper();
let buff = 'TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNz\r\naW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZl\r\naGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU=\r\n';
let result = base64Helper.decodeSync(buff, util.Type.MIME);
console.info("result = " + result);
/*
输出结果：result = 77,97,110,105,115,100,105,115,116,105,110,103,117,105,115,104,101,100,110,111,116,111,110,108,121,98,121,104,105,115,114,101,97,115,111,110,98,117,116,98,121,116,104,105,115,115,105,110,103,117,108,97,114,112,97,115,115,105,111,110,102,114,111,109,111,116,104,101,114,97,110,105,109,97,108,115,119,104,105,99,104,105,115,97,108,117,115,116,111,102,116,104,101,109,105,110,100,101,120,99,101,101,100,115,116,104,101,115,104,111,114,116,118,101,104,101,109,101,110,99,101,111,102,97,110,121,99,97,114,110,97,108,112,108,101,97,115,117,114,101
*/

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