我想从 azure blob 存储中获取图像并将其发送到客户端，而不将其保存在本地。我能够从 blob 存储获取图像并将其保存到本地文件，但很难将其发送到客户端而不保存在本地。请在下面找到代码
const containerClient = blobServiceClient.getContainerClient(containerName);
const blockBlobClient = containerClient.getBlobClient(blobName);
const downloadBlockBlobResponse = await blockBlobClient.download(0);
console.log('\nDownloaded blob content...');
let f = await streamToString(downloadBlockBlobResponse.readableStreamBody)
reply.type('image/jpg').send(f)
streamToString函数如下
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);
});
}
运行此代码时，浏览器中出现空白屏幕
最佳答案
如果您想从 Azure Blob 存储中获取图像并将其发送到客户端而不将其保存在本地，则 Node 服务器会发送 SAS token我认为客户端直接从 Azure 存储获取此图像将是更好的解决方案。也减轻了Node服务器的压力:生成SAS token并发送给客户端就可以了，不需要从Storage中读取数据。
尝试使用以下代码生成 SAS token :
var azure = require('azure-storage');
var connString = "your storage connection string";
var container ="your container name";
var blobName = "your image name"
var blobService = azure.createBlobService(connString);
// Create a SAS token that expires in an hour
// Set start time to five minutes ago to avoid clock skew.
var startDate = new Date();
startDate.setMinutes(startDate.getMinutes() - 5);
var expiryDate = new Date(startDate);
expiryDate.setMinutes(startDate.getMinutes() + 60);
var sharedAccessPolicy = {
AccessPolicy: {
Permissions: [azure.BlobUtilities.SharedAccessPermissions.READ], //grent read permission only
Start: startDate,
Expiry: expiryDate
}
};
var sasToken = blobService.generateSharedAccessSignature(container, blobName, sharedAccessPolicy);
var response = {};
response.image = blobService.getUrl(container,blobName,sasToken);
res.send(response);
结果:
客户端可以使用此图像 URL 直接从存储访问此图像:
尝试将 imageURL 转换为 base64 图像内容，以便您可以直接根据内容保存/显示图像:
<html>
<body>
<img id="displayImg">
</body>
<script>
var nodeResult = {"image":"https://stantest1016.blob.core.windows.net/stantest/test.jpeg?st=2020-10-26T04%3A53%3A51Z&se=2020-10-26T05%3A53%3A51Z&sp=r&sv=2018-03-28&sr=b&sig=ZjY3LYbgvMn%2BSr4dAEUoqidVRT4YyH1FcW1DeKlpjYo%3D"}
function getImageData(nodeResult){
var xhr = new XMLHttpRequest();
xhr.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var reader = new FileReader();
reader.readAsDataURL(this.response);
reader.onload = function() {
document.getElementById('displayImg').src = reader.result;
}
};
};
xhr.open('GET', nodeResult.image);
xhr.responseType = 'blob';
xhr.send();
}
getImageData(nodeResult);
</script>
</html>
结果:
标签详细信息:
关于node.js - 从 azure-blob 获取图像并将其发送到客户端，而不使用 Node 服务器本地保存，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/64443295/