[英]How to get azure blob storage content in FileInputStream in Java?
我正在研究 API(彈簧靴)。 其中我需要在 get 方法的響應體中返回 FileInputStream。
預期- 當前端調用 get-files API 時,應在瀏覽器上打開文件下載提示。
問題- 我們不能使用 blob.downloadToFile 方法,因為它會在本地機器(或托管 API 的地方)下載文件,我們需要一些東西,我們可以使用它在 API 調用中將文件直接發送到前端。 然而,還有另一種方法blob.download() ,它返回 OutputStream ,它不能在 API 調用中返回。
那么有什么方法可以將 OutputStream 轉換為 FileInputStream 而無需保存到我們設備上的實際文件。
示例代碼 -
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-文件可以是任何類型。
這是解決方案 - 在瀏覽器中點擊 API 后,您的文件將在瀏覽器中下載 -
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);
}
}
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