javascript - axios图片流Base64编码后转成字符串？

Question

到目前为止我有这个:

const Fs = require('fs')  
const Path = require('path')  
const Axios = require('axios')
var {Base64Encode} = require('base64-stream');

const url = 'https://unsplash.com/photos/AaEQmoufHLk/download?force=true'

const response = await Axios({
      url,
      method: 'GET',
      responseType: 'stream'
    })

response.data.pipe(new Base64Encode())

此 base 64 对图像进行编码。我们怎样才能把它变成一个字符串。我试过这样的事情:

  function streamToString (stream) {
    const chunks = []
    return new Promise((resolve, reject) => {
      stream.on('data', chunk => chunks.push(chunk))
      stream.on('error', reject)
      stream.on('end', () => resolve(Buffer.concat(chunks).toString('utf8')))
    })
  }

const result = await streamToString(response.data.pipe(new Base64Encode()))

但是它出错了。想法？

Answer 1

在您的示例中，您使用了已经输出字符串的 Base64encode 模块 - 这使得上面的示例失败(除非那是因为顶层等待)。您实际上不需要将 block 转换为字符串，因为它们已经是字符串，所以简单的连接就可以了。

事实上，仅使用 node.js 流，整个事情可能会简单 10 倍:

const Axios = require('axios')
const {PassThrough} = require("stream");

const url = 'https://unsplash.com/photos/AaEQmoufHLk/download?force=true';

(async function() {
    const response = await Axios({
        url,
        method: 'GET',
        responseType: 'stream'
    });

    // we just pipe the data (the input carries it's own encoding)
    // to a PassThrough node stream that outputs `base64`.
    const chunks = response.data
        .pipe(new PassThrough({encoding:'base64'}));

    // then we use an async generator to read the chunks
    let str = '';
    for await (let chunk of chunks) {
        str += chunk;
    }

    // et voila! :)
    console.log(str);
})();