如何临时存储文件、处理然后删除？

Question

我正在尝试使用nodejs/express 创建一个后端，其中上传的文件的数据将由adobe api 提取。需要API

let readStream:fs.ReadStream | undefined = fs.createReadStream(inputFile)                                                          const inputAsset = await pdfServices.upload({readStream, mimeType: MimeType.PDF}); 

现在我需要从上传的文件创建一个读取流。我需要存储它还是可以直接存储它？这个问题有什么好的解决办法吗？

Answer 1

您可以使用哈希函数来确保您收到整个 PDF 文件，而不是将文件存储在服务器端（

pdfService

）。

const crypto = require('crypto');

/**
 * Consumes the readStream, and returns hexidecimal 
 * digest sum calculated over the content of the readStream
 */
function calculateHashFromStream(readStream, algorithm = 'sha256') {
  return new Promise((resolve, reject) => {
    const hash = crypto.createHash(algorithm);

    readStream.on('data', chunk => {
      hash.update(chunk);
    });

    readStream.on('end', () => {
      resolve(hash.digest('hex'));
    });

    readStream.on('error', err => {
      reject(err);
    });
  });
}

要使用 PDF 数据尝试上述功能：

const { Readable } = require('node:stream');

// Emulating PDF data as a string
const pdfData = `
%PDF-1.4
1 0 obj
<< /Type /Catalog /Pages 2 0 R >>
endobj
2 0 obj
<< /Type /Pages /Count 1 >>
endobj
xref
0 3
0000000000 65535 f
0000000010 00000 n
0000000067 00000 n
trailer
<< /Root 1 0 R >>
startxref
120
%%EOF
`;

// Create a Readable stream from the PDF data
const fakePdfStream = Readable.from(pdfData);

// Calculate the hash of the simulated PDF data
calculateHashFromStream(fakePdfStream, 'sha256')
    .then((hash) => {
        console.log(`Hash of simulated PDF data: ${hash}`);
    });

输出：

Hash of simulated PDF data: cc9addcba71e150169eb239898e3e9a8d8f6269f98bc0c28fa18359fc77167e5