如何使用javascript从stringstream内容azure blob存储下载png文件

Question

我写了这段代码来获取数据，我得到了这样的响应

async function streamToString(readableStream) {
  return new Promise((resolve, reject) => {
    const chunks = [];
    readableStream.on("data", (data) => {
      chunks.push(data.toString());
    });
    readableStream.on("end", () => {
      resolve(chunks.join(""));
    });
    readableStream.on("error", reject);
  });
}

if (type == "download") {
  const name = req.query.name || req.body.name;
  const itemname = req.query.itemname || req.body.itemname;
  var container = name ? name : "securesharecc";
  const containerClient = await blobServiceClient.getContainerClient(container);
  const blobName = itemname ? itemname : "sample.png";
  const blockBlobClient = containerClient.getBlockBlobClient(blobName);
  const downloadBlockBlobResponse = await blockBlobClient.download(0);
  console.log("\nDownloaded blob content...");
  var a = await streamToString(downloadBlockBlobResponse.readableStreamBody);
  console.log("\t", a);
  context.res = {
    body: { data: a }
  };
  context.done();
}

因此，此代码使用 azure 容器中的项目名称下载文件。

但我收到这样的回复

{
  "data": "PNG\r\n\u001a\n\u0000\u0000\u0000\rIHDR\u0000\u0000\u0002�\u0000\u0000\u0001�\b\u0002\u0000\u0000\u0000\u000f�\u001fl\u0000\u0000\u0000\u0001sRGB\u0000��\u001c�\u0000\u0000\u0000\u0004gAMA\u0000\u0000��\u000b ....."
}

我想直接下载这个文件而不是显示内容，怎么做？

Answer 1

请尝试将您的streamToString方法更改为以下内容：

async function streamToString(readableStream) {
  return new Promise((resolve, reject) => {
    let chunks = Buffer.from([]);
    readableStream.on("data", (data) => {
      chunks = Buffer.concat([chunks, data], chunks.length + data.length);
    });
    readableStream.on("end", () => {
      resolve(chunks);
    });
    readableStream.on("error", reject);
  });
}

本质上，图像文件是二进制文件，您不应该尝试将其数据转换为字符串。