javascript - node.js axios 下载文件流和writeFile

Question

我想下载一个pdf文件axios并保存在磁盘（服务器端）上fs.writeFile，我试过：

axios.get('https://xxx/my.pdf', {responseType: 'blob'}).then(response => {
    fs.writeFile('/temp/my.pdf', response.data, (err) => {
        if (err) throw err;
        console.log('The file has been saved!');
    });
});

文件已保存，但内容已损坏...

如何正确保存文件？

标签： javascriptnode.jsaxios

Answer 1

实际上，我相信之前接受的答案有一些缺陷，因为它不能正确处理 writestream，所以如果你在 Axios 给你响应之后调用“then()”，你最终会得到一个部分下载的文件。

当下载稍大的文件时，这是一个更合适的解决方案：

export async function downloadFile(fileUrl: string, outputLocationPath: string) {
  const writer = createWriteStream(outputLocationPath);

  return Axios({
    method: 'get',
    url: fileUrl,
    responseType: 'stream',
  }).then(response => {

    //ensure that the user can call `then()` only when the file has
    //been downloaded entirely.

    return new Promise((resolve, reject) => {
      response.data.pipe(writer);
      let error = null;
      writer.on('error', err => {
        error = err;
        writer.close();
        reject(err);
      });
      writer.on('close', () => {
        if (!error) {
          resolve(true);
        }
        //no need to call the reject here, as it will have been called in the
        //'error' stream;
      });
    });
  });
}

这样，您可以调用downloadFile()，调用then()返回的承诺，并确保下载的文件已完成处理。

或者，如果你使用更现代的 NodeJS 版本，你可以试试这个：

import * as stream from 'stream';
import { promisify } from 'util';

const finished = promisify(stream.finished);

export async function downloadFile(fileUrl: string, outputLocationPath: string): Promise<any> {
  const writer = createWriteStream(outputLocationPath);
  return Axios({
    method: 'get',
    url: fileUrl,
    responseType: 'stream',
  }).then(async response => {
    response.data.pipe(writer);
    return finished(writer); //this is a Promise
  });
}