Access Private Objects Using Presigned URLs

For private objects stored in OSS, use a presigned URL to grant temporary access without modifying bucket or object permissions. The following steps demonstrate how to generate and use a presigned URL with the AWS SDK for Java (v2).

Steps:

1. Initialise S3Presigner

   Create an S3Presigner instance with the required credentials, region, and OSS endpoint:

   public S3Presigner createS3Presigner() {
       AwsBasicCredentials awsCredentials = AwsBasicCredentials.create("accessKeyId", "secretAccessKey");
   
       return S3Presigner.builder()
               .serviceConfiguration(S3Configuration.builder().pathStyleAccessEnabled(true).build())
               .region(Region.of("default"))
               .endpointOverride(URI.create("Access Endpoint"))
               .credentialsProvider(StaticCredentialsProvider.create(awsCredentials))
               .build();
   }

2. Generate a Presigned URL

   Generate a presigned URL valid for a specific duration (e.g., 10 minutes):

   public String createPresignedGetUrl(String bucketName, String keyName) {
       try (S3Presigner presigner = S3Presigner.create()) {
   
           GetObjectRequest objectRequest = GetObjectRequest.builder()
                   .bucket(bucketName)
                   .key(keyName)
                   .build();
   
           GetObjectPresignRequest presignRequest = GetObjectPresignRequest.builder()
                   .signatureDuration(Duration.ofMinutes(10))
                   .getObjectRequest(objectRequest)
                   .build();
   
           PresignedGetObjectRequest presignedRequest = presigner.presignGetObject(presignRequest);
           return presignedRequest.url().toExternalForm();
       }
   }

3. Access the Object

   Use a standard HTTP client to access the object with the presigned URL:

   public byte[] useHttpUrlConnectionToGet(String presignedUrlString) {
       ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
   
       try {
           URL presignedUrl = new URL(presignedUrlString);
           HttpURLConnection connection = (HttpURLConnection) presignedUrl.openConnection();
           connection.setRequestMethod("GET");
   
           try (InputStream content = connection.getInputStream()) {
               IoUtils.copy(content, byteArrayOutputStream);
           }
   
       } catch (S3Exception | IOException e) {
           logger.error(e.getMessage(), e);
       }
   
       return byteArrayOutputStream.toByteArray();
   }