“没有这样的文件或目录”:从S3下载多个文件

我有一个API方法,当调用并传递一个文件密钥字符串时,它将该字符串转换为数组,然后从S3下载它们。但是,当我调用这个API时,我得到了错误 Error: ENOENT: no such file or directory, open <filename here> 在服务器上。

这是我的API:

reports.get('/xxx/:fileName', async (req, res) => {

  var AWS = require('aws-sdk');

  var s3 = new AWS.S3();

  var str_array = req.params.fileName.split(','); 

  for (var i = 0; i < str_array.length; i++) {
    var filename = str_array[i].trim();
    localFileName = './' + filename;

    let file = fs.createWriteStream(localFileName);   

    s3.getObject({
      Bucket: config.reportBucket,
      Key: filename
    })
    .on('error', function (err) {
      res.end("File download failed with error " + err.message);            
    })
    .on('httpData', function (chunk) {
      file.write(chunk);
    })
    .on('httpDone', function () {
      file.end();
    })
    .send();
  }
  res.end("Files have been downloaded successfully")
});

如何通过传递密钥数组从S3成功下载多个文件?