為 Amazon S3 目錄儲存貯體建立預先簽章的 URL，以使用 AWS SDK 取得物件

產生預先簽章的 GET URL，以存取 S3 目錄儲存貯體中的物件。

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.GetObjectRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;
import software.amazon.awssdk.services.s3.presigner.S3Presigner;
import software.amazon.awssdk.services.s3.presigner.model.GetObjectPresignRequest;
import software.amazon.awssdk.services.s3.presigner.model.PresignedGetObjectRequest;

import java.nio.file.Path;
import java.time.Duration;

import static com.example.s3.util.S3DirectoryBucketUtils.createDirectoryBucket;
import static com.example.s3.util.S3DirectoryBucketUtils.createS3Client;
import static com.example.s3.util.S3DirectoryBucketUtils.createS3Presigner;
import static com.example.s3.util.S3DirectoryBucketUtils.deleteAllObjectsInDirectoryBucket;
import static com.example.s3.util.S3DirectoryBucketUtils.deleteDirectoryBucket;
import static com.example.s3.util.S3DirectoryBucketUtils.getFilePath;
import static com.example.s3.util.S3DirectoryBucketUtils.putDirectoryBucketObject;


    /**
     * Generates a presigned URL for accessing an object in the specified S3
     * directory bucket.
     *
     * @param s3Presigner The S3 presigner client used to generate the presigned URL
     * @param bucketName  The name of the directory bucket
     * @param objectKey   The key (name) of the object to access
     * @return A presigned URL for accessing the specified object
     */
    public static String generatePresignedGetURLForDirectoryBucket(S3Presigner s3Presigner, String bucketName,
            String objectKey) {
        logger.info("Generating presigned URL for object: {} in bucket: {}", objectKey, bucketName);

        try {
            // Create a GetObjectRequest
            GetObjectRequest getObjectRequest = GetObjectRequest.builder()
                    .bucket(bucketName)
                    .key(objectKey)
                    .build();

            // Create a GetObjectPresignRequest
            GetObjectPresignRequest getObjectPresignRequest = GetObjectPresignRequest.builder()
                    .signatureDuration(Duration.ofMinutes(10)) // Presigned URL valid for 10 minutes
                    .getObjectRequest(getObjectRequest)
                    .build();

            // Generate the presigned URL
            PresignedGetObjectRequest presignedGetObjectRequest = s3Presigner.presignGetObject(getObjectPresignRequest);

            // Get the presigned URL
            String presignedURL = presignedGetObjectRequest.url().toString();
            logger.info("Presigned URL: {}", presignedURL);
            return presignedURL;

        } catch (S3Exception e) {
            logger.error("Failed to generate presigned URL: {} - Error code: {}", e.awsErrorDetails().errorMessage(),
                    e.awsErrorDetails().errorCode(), e);
            throw e;
        }
    }