使用nodejs和blob服务从blob存储下载子目录/目录？

Question

我已经使用 blob 服务的 getBlobProperties() 和 createReadStream(containerName, fullPath, options) 方法实现了下载文件。现在，我正在尝试使用相同的方法在我的容器中下载目录/子目录，但它不起作用，并且抛出错误，指定的 blob 不存在。尽管我知道此错误的原因，但由于我不想循环 blob 并分别下载每个文件，我该如何克服这个问题？我要下载一个完整的文件夹。

这里是 API：

exports.getBlobChunk = function (req, res) {
var userrole = utils.sanitizeStr(req.body.userrole);
var srcFilePath = utils.sanitizeStr(req.body.srcfilePath);
var fileName = utils.sanitizeStr(req.body.srcfileName);
var fullPath = srcFilePath + "/" + fileName;
var startRange = req.headers['startrange'];
var endRange = req.headers['endrange'];
genericHandler.getUserSubscMapping().then(function (results) {
if (results != undefined && results != null) {
var item = results[0].mapping.find(item => item.name == userrole);
var sasurl = item.sasurl;
if (sasurl == null) {
res.status(500).send("Subscription mapping not configured");
return;
}
var host = sasurl.substring(0, sasurl.lastIndexOf("/"));
var containerName = sasurl.substring(sasurl.lastIndexOf("/"), sasurl.indexOf("?")).split("/")[1];
var saskey = sasurl.substring(sasurl.indexOf("?"), sasurl.length);
var download = item.download; // download usage
var blobService = storage.createBlobServiceWithSas(host, saskey);
blobService.getBlobProperties(containerName, fullPath, function (err, properties, status) {
if (err) {
res.send(502, "Error fetching file: %s", err.message);
} else if (!status.isSuccessful) {
res.send(404, "The file %s does not exist", fullPath);
} else {
var contentLength = properties.contentLength / 1024; // bytes to KB
res.header('Content-Type', "application/zip");
res.attachment(fileName);
var options = {
rangeStart: startRange,
rangeEnd: endRange
};
if (startRange == 0) { // update download size on first chunk
exports.updateStorageDownload(userrole, contentLength, download);
}
blobService.createReadStream(containerName, fullPath, options).pipe(res);
}
});
}

Answer 1

Azure Blob 存储没有文件夹的概念，容器内的所有内容都被视为一个 Blob，包括文件夹。所以你不能下载带有文件夹名称的目录/子目录。

例如：

• 容器结构

    hello.txt
    ...
    test
        test.txt
        test1
            data.json
  

您需要从目录中一个一个地下载blob文件。

const {
  BlobServiceClient,
  StorageSharedKeyCredential,
} = require("@azure/storage-blob");

// Enter your storage account name and shared key
const account = "";
const accountKey ="";
const containerName = "";
const filePath = "D:/downloads/"

// Use StorageSharedKeyCredential with storage account and account key
// StorageSharedKeyCredential is only available in Node.js runtime, not in browsers
const sharedKeyCredential = new StorageSharedKeyCredential(account, accountKey);
const blobServiceClient = new BlobServiceClient(
  `https://${account}.blob.core.windows.net`,
  sharedKeyCredential,
);


async function listBlobs() {
  const containerClient = await blobServiceClient.getContainerClient(containerName);
  console.log("list blobs with method listBlobsFlat");
  let iter = containerClient.listBlobsFlat({ prefix: "test/" });
  for await (const item of iter) {
    console.log(`\tBlobItem: name - ${item.name}`);
    downloadBlobToLocal(containerClient, item.name, filePath);
  }
  console.log("list blobs with method listBlobsByHierarchy");
  let iter1 = containerClient.listBlobsByHierarchy("/", { prefix: "test/" });
  for await (const item of iter1) {
    if (item.kind === "prefix") {
      console.log(`\tBlobPrefix: ${item.name}`);
      await listblob(containerClient, item.name);
    } else {
      console.log(`\tBlobItem: name - ${item.name}`);
      downloadBlobToLocal(containerClient, item.name, filePath);
    }
  }
}

async function listblob(containerClient, prefix) {
  let iter1 = containerClient.listBlobsByHierarchy("/", { prefix: prefix });
  for await (const item of iter1) {
    if (item.kind === "prefix") {
      console.log(`\tBlobPrefix: ${item.name}`);
    } else {
      console.log(`\tBlobItem: name - ${item.name}`);
      downloadBlobToLocal(containerClient, item.name, filePath);
    }
  }
}

async function downloadBlobToLocal(containerClient, blobName, filePath) {
    const blockBlobClient = containerClient.getBlockBlobClient(blobName);
    const downloadBlockBlobResponse = await blockBlobClient.downloadToFile(filePath + blobName);
}

listBlobs().catch((err) => {
  console.error("Error running sample:", err.message);
});