Javascript中Uint8Array的字符串

我有一些UTF-8编码的数据生活在Javascript Uint8Array元素的范围内。是否有一种有效的方法来解码这些到一个常规的javascript字符串(我相信javascript使用16位Unicode)?我不想一次添加一个字符，因为字符串连接会变得CPU密集。

当前回答

这应该可以工作:

// http://www.onicos.com/staff/iz/amuse/javascript/expert/utf.txt

/* 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.
 */

function Utf8ArrayToStr(array) {
    var out, i, len, c;
    var char2, char3;

    out = "";
    len = array.length;
    i = 0;
    while(i < len) {
    c = array[i++];
    switch(c >> 4)
    { 
      case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
        // 0xxxxxxx
        out += String.fromCharCode(c);
        break;
      case 12: case 13:
        // 110x xxxx   10xx xxxx
        char2 = array[i++];
        out += String.fromCharCode(((c & 0x1F) << 6) | (char2 & 0x3F));
        break;
      case 14:
        // 1110 xxxx  10xx xxxx  10xx xxxx
        char2 = array[i++];
        char3 = array[i++];
        out += String.fromCharCode(((c & 0x0F) << 12) |
                       ((char2 & 0x3F) << 6) |
                       ((char3 & 0x3F) << 0));
        break;
    }
    }

    return out;
}

与其他解决方案相比，它更简洁，因为它不使用任何hack，也不依赖于浏览器JS函数，例如，也可以在其他JS环境中工作。

查看JSFiddle演示。

请参见相关问题:这里和这里

2014-03-13 08:41:46

其他回答

试试这些函数，

var JsonToArray = function(json)
{
    var str = JSON.stringify(json, null, 0);
    var ret = new Uint8Array(str.length);
    for (var i = 0; i < str.length; i++) {
        ret[i] = str.charCodeAt(i);
    }
    return ret
};

var binArrayToJson = function(binArray)
{
    var str = "";
    for (var i = 0; i < binArray.length; i++) {
        str += String.fromCharCode(parseInt(binArray[i]));
    }
    return JSON.parse(str)
}

来源:https://gist.github.com/tomfa/706d10fed78c497731ac，向Tomfa致敬

2018-06-22 16:20:33

我很沮丧地看到，人们没有显示如何双向或显示事情的工作在不平凡的UTF8字符串。我在codereview.stackexchange.com上找到了一个帖子，其中有一些运行良好的代码。我用它把古老的符文转换成字节，在字节上测试一些加密，然后把东西转换回字符串。工作代码在github这里。为了清晰起见，我重命名了这些方法:

// https://codereview.stackexchange.com/a/3589/75693
function bytesToSring(bytes) {
    var chars = [];
    for(var i = 0, n = bytes.length; i < n;) {
        chars.push(((bytes[i++] & 0xff) << 8) | (bytes[i++] & 0xff));
    }
    return String.fromCharCode.apply(null, chars);
}

// https://codereview.stackexchange.com/a/3589/75693
function stringToBytes(str) {
    var bytes = [];
    for(var i = 0, n = str.length; i < n; i++) {
        var char = str.charCodeAt(i);
        bytes.push(char >>> 8, char & 0xFF);
    }
    return bytes;
}

单元测试使用这个UTF-8字符串:

    // http://kermitproject.org/utf8.html
    // From the Anglo-Saxon Rune Poem (Rune version) 
    const secretUtf8 = `ᚠᛇᚻ᛫ᛒᛦᚦ᛫ᚠᚱᚩᚠᚢᚱ᛫ᚠᛁᚱᚪ᛫ᚷᛖᚻᚹᛦᛚᚳᚢᛗ
ᛋᚳᛖᚪᛚ᛫ᚦᛖᚪᚻ᛫ᛗᚪᚾᚾᚪ᛫ᚷᛖᚻᚹᛦᛚᚳ᛫ᛗᛁᚳᛚᚢᚾ᛫ᚻᛦᛏ᛫ᛞᚫᛚᚪᚾ
ᚷᛁᚠ᛫ᚻᛖ᛫ᚹᛁᛚᛖ᛫ᚠᚩᚱ᛫ᛞᚱᛁᚻᛏᚾᛖ᛫ᛞᚩᛗᛖᛋ᛫ᚻᛚᛇᛏᚪᚾ᛬`;

请注意，字符串长度只有117个字符，但编码时字节长度为234。

如果我取消console.log行注释，我可以看到解码的字符串与编码的字符串相同(通过Shamir的秘密共享算法传递的字节!):

2019-06-19 07:12:08

对于香草，浏览器端，从麦克风录音，base64函数为我工作(我必须实现一个音频发送功能到聊天)。

      const ui8a =  new Uint8Array(e.target.result);
      const string = btoa(ui8a);
      const ui8a_2 = atob(string).split(',');

现在是完整代码。感谢Bryan Jennings & breakspirit@py4u.net提供的代码。

https://medium.com/@bryanjenningz/how-to-record-and-play-audio-in-javascript-faa1b2b3e49b

https://www.py4u.net/discuss/282499

index . html

<html>
  <head>
    <title>Record Audio Test</title>
    <meta name="encoding" charset="utf-8" />
  </head>
  <body>
    <h1>Audio Recording Test</h1>
    <script src="index.js"></script>
    <button id="action" onclick="start()">Start</button>
    <button id="stop" onclick="stop()">Stop</button>
    <button id="play" onclick="play()">Listen</button>
  </body>
</html>

index.js:

const recordAudio = () =>
  new Promise(async resolve => {
    const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
    const mediaRecorder = new MediaRecorder(stream);
    const audioChunks = [];

    mediaRecorder.addEventListener("dataavailable", event => {
      audioChunks.push(event.data);
    });

    const start = () => mediaRecorder.start();

    const stop = () =>
      new Promise(resolve => {
        mediaRecorder.addEventListener("stop", () => {
          const audioBlob = new Blob(audioChunks);
          const audioUrl = URL.createObjectURL(audioBlob);
          const audio = new Audio(audioUrl);
          const play = () => audio.play();
          resolve({ audioBlob, audioUrl, play });
        });

        mediaRecorder.stop();
      });

    resolve({ start, stop });
  });

let recorder = null;
let audio = null;
const sleep = time => new Promise(resolve => setTimeout(resolve, time));

const start = async () => {
  recorder = await recordAudio();
  recorder.start();
}

const stop = async () => {
  audio = await recorder.stop();
  read(audio.audioUrl);
}

const play = ()=> {
  audio.play();
}

const read = (blobUrl)=> {

  var xhr = new XMLHttpRequest;
  xhr.responseType = 'blob';
  
  xhr.onload = function() {
      var recoveredBlob = xhr.response;
      const reader = new FileReader();
      // This fires after the blob has been read/loaded.
      reader.addEventListener('loadend', (e) => {

          const ui8a =  new Uint8Array(e.target.result);
          const string = btoa(ui8a);
          const ui8a_2 = atob(string).split(',');
          
          playByteArray(ui8a_2);
      });
      // Start reading the blob as text.
      reader.readAsArrayBuffer(recoveredBlob);
  };
  // get the blob through blob url 
  xhr.open('GET', blobUrl);
  xhr.send();
}

window.onload = init;
var context;    // Audio context
var buf;        // Audio buffer

function init() {
  if (!window.AudioContext) {
      if (!window.webkitAudioContext) {
          alert("Your browser does not support any AudioContext and cannot play back this audio.");
          return;
      }
        window.AudioContext = window.webkitAudioContext;
    }

    context = new AudioContext();
}

function playByteArray(byteArray) {

    var arrayBuffer = new ArrayBuffer(byteArray.length);
    var bufferView = new Uint8Array(arrayBuffer);
    for (i = 0; i < byteArray.length; i++) {
      bufferView[i] = byteArray[i];
    }

    context.decodeAudioData(arrayBuffer, function(buffer) {
        buf = buffer;
        play2();
    });
}

// Play the loaded file
function play2() {
    // Create a source node from the buffer
    var source = context.createBufferSource();
    source.buffer = buf;
    // Connect to the final output node (the speakers)
    source.connect(context.destination);
    // Play immediately
    source.start(0);
}

2021-10-10 14:46:26

对于ES6和UTF8字符串

decodeURIComponent(escape(String.fromCharCode(...uint8arrData)))

2021-12-17 08:53:34

以下是我使用的方法:

var str = String.fromCharCode.apply(null, uint8Arr);

2013-09-30 19:28:22

Javascript中Uint8Array的字符串

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