如何在 Java 的 FileInputStream 中获取 azure blob 存储内容？

Question

我正在开发 API（spring 启动）。其中我需要 return FileInputStream 在 get 方法的响应体中。

预期 - 前端调用get-files时API，浏览器应该会打开文件下载提示

问题 - 我们不能使用 blob.downloadToFile 方法，因为它会将文件下载到本地机器（或托管 API 的地方）我们需要一些东西，我们可以使用它在 API 调用时将文件直接发送到前端。然而，还有另一种方法 blob.download()，其中 returns OutputStream 不能在 API 调用时被 returned。

那么有什么方法可以将 OutputStream 转换为 FileInputStream 而无需保存到我们设备上的实际文件。

示例代码-

public ByteArrayOutputStream downloadBlob() throws URISyntaxException, InvalidKeyException, StorageException, IOException {
        String storageConnectionString = "DefaultEndpointsProtocol=https;" + "AccountName=" + accountName + ";"
                + "AccountKey=" + accountKey;

        CloudStorageAccount storageAccount = CloudStorageAccount.parse(storageConnectionString);

        CloudBlobClient blobClient = storageAccount.createCloudBlobClient();

        final CloudBlobContainer container = blobClient.getContainerReference("container name");


        CloudBlockBlob blob = container.getBlockBlobReference("image.PNG");
        ByteArrayOutputStream outputStream =new ByteArrayOutputStream();
        blob.download(outputStream);
        System.out.println("file downloaded");

        return outputStream;
    }

注意-文件可以是任何类型。

Answer 1

这是解决方案 - 在浏览器中点击 API 后，您的文件将在浏览器中下载 -

package com.example.demo.controllers;

import com.azure.storage.blob.BlobClient;
import com.azure.storage.blob.BlobContainerClient;
import com.azure.storage.blob.BlobServiceClient;
import com.azure.storage.blob.BlobServiceClientBuilder;
import org.springframework.core.io.ByteArrayResource;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;


@RestController
public class FileDownload {
    @GetMapping(path="/download-file")
    public ResponseEntity<Resource> getFile(){
        String fileName = "Can not find symbol.docx";
        //azure credentials
        String connection_string = "Connection String of storage account on azure";

        BlobServiceClient blobServiceClient = new BlobServiceClientBuilder().connectionString(connection_string).buildClient();

        BlobContainerClient containerClient= blobServiceClient.getBlobContainerClient("Container name");
        System.out.println(containerClient.getBlobContainerName());

        BlobClient blob = containerClient.getBlobClient(fileName);

        //creating an object of output stream to recieve the file's content from azure blob.
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        blob.download(outputStream);

        //converting it to the inputStream to return
        final byte[] bytes = outputStream.toByteArray();
        ByteArrayInputStream inputStream = new ByteArrayInputStream(bytes);
        ByteArrayResource resource = new ByteArrayResource(bytes);
        HttpHeaders headers = new HttpHeaders();
        headers.add(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"");

        return ResponseEntity.ok().contentType(MediaType.APPLICATION_OCTET_STREAM)
                .headers(headers)
                .body(resource);
    }

}

如何在 Java 的 FileInputStream 中获取 azure blob 存储内容？

How to get azure blob storage content in FileInputStream in Java?

java

cloud

spring

blob

azure