javascript - 使用 s3 getobjectcommand 结果以 Angular (以 pdf 形式打开)

Question

我正在尝试使用 Angular 作为 pdf 从 s3 存储桶中打开文件。为此，我运行一个 Node 服务来获取我从 Angular 调用的对象。然后我尝试以 pdf 形式打开 Angular 。我有什么遗漏的吗？当我打开 PDF 时，它显示为空白(白色)文档。

下面是我的 Node 代码:

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

const readFile = async function getObj(key) {
  const params = {
    Bucket: vBucket,
    Key: key,
  };
  const command = new GetObjectCommand(params);
  const response = await client.send(command);
  const { Body } = response; 
  return streamToString(Body);
};

在这里，我正在使用 Angular 并以 PDF 形式打开

服务:

  getObj(key: String): Observable<any>{
    const httpOptions = {
      'responseType'  : 'arraybuffer' as 'json'
       //'responseType'  : 'blob' as 'json'        //This also worked
    };
    return this.http.get<any>(environment.s3Ep + '/getfile?key=' + key, httpOptions );
  }

以及使用该服务的代码:

this.s3Svc.getObj(key).subscribe(
  res => {
    let file = new Blob([res], {type: 'application/pdf'});
    var fileURL = URL.createObjectURL(file);
    window.open(fileURL);
  } 
);

Answer 1

我开始遇到同样的问题。找到了解决方案，将streamToString替换为streamToBuffer，如下:

const streamToBuffer = async (stream: Readable): Promise<Buffer> => {
  return new Promise((resolve, reject) => {
    const chunks: Array<any> = []
    stream.on('data', (chunk) => chunks.push(chunk))
    stream.on('error', reject)
    stream.on('end', () => resolve(Buffer.concat(chunks)))
  })
}

以及使用它的代码:

  const command = new GetObjectCommand({ Bucket, Key })
  const data = await s3.send(command)
  const content = await streamToBuffer(data.Body as Readable)
  fs.writeFileSync(destPath, content)

就我而言，我正在写入 PDF 文件。 写入从streamToString检索的字符串或写入buffer.toString()会导致空白PDF。