# 使用 Amazon SDK 为 Amazon S3 目录存储桶创建获取对象的预签名 URL
<a name="s3-directory-buckets_example_s3-directory-buckets_GeneratePresignedGetURLForDirectoryBucket_section"></a>

以下代码示例演示如何为 S3 目录存储桶创建预签名 URL 以及获取对象。

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#### [ Java ]

**适用于 Java 的 SDK 2.x**  
 查看 GitHub，了解更多信息。在 [Amazon 代码示例存储库](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/s3/src/main/java/com/example/s3/directorybucket#code-examples)中查找完整示例，了解如何进行设置和运行。
生成用于访问 S3 目录存储桶中的对象的预签名 GET URL。  

```
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;
        }
    }
```
+  有关 API 详细信息，请参阅《Amazon SDK for Java 2.x API Reference》**中的 [GetObject](https://docs.amazonaws.cn/goto/SdkForJavaV2/s3-2006-03-01/GetObject)。

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有关 Amazon SDK 开发人员指南和代码示例的完整列表，请参阅 [使用 Amazon SDK 通过 Amazon S3 进行开发](sdk-general-information-section.md)。本主题还包括有关入门的信息以及有关先前的 SDK 版本的详细信息。