刚帮团队里的人踩过这个坑，SDK 2.0的预签名URL生成逻辑和1.x版本差异挺大的，官方旧文档确实没及时更新对应的2.0示例。下面给你整理了完整的实现代码和注意事项：

第一步：确认依赖配置 #

首先确保你的项目里引入了AWS SDK 2.0的S3相关依赖，以Maven为例：

<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>s3</artifactId>
    <version>2.20.0</version> <!-- 替换成最新稳定版即可 -->
</dependency>
<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>url-connection-client</artifactId>
    <version>2.20.0</version>
</dependency>

生成预签名URL（GET下载场景） #

这个场景用于生成让用户下载S3对象的预签名链接：

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Presigner;
import software.amazon.awssdk.services.s3.model.GetObjectRequest;
import software.amazon.awssdk.services.s3.model.PresignedGetObjectRequest;
import java.net.URL;
import java.time.Duration;

public class GeneratePresignedUrlForGet {
    public static void main(String[] args) {
        String bucketName = "your-bucket-name";
        String objectKey = "path/to/your/object.txt";
        Region region = Region.US_EAST_1; // 替换成你的桶所在区域

        // 初始化S3Presigner，注意用完要关闭
        try (S3Presigner presigner = S3Presigner.builder()
                .region(region)
                .build()) {

            // 创建Get请求
            GetObjectRequest getObjectRequest = GetObjectRequest.builder()
                    .bucket(bucketName)
                    .key(objectKey)
                    .build();

            // 生成预签名请求，设置有效期（比如1小时）
            PresignedGetObjectRequest presignedRequest = presigner.presignGetObject(r -> r
                    .signatureDuration(Duration.ofHours(1))
                    .getObjectRequest(getObjectRequest));

            // 获取最终的预签名URL
            URL presignedUrl = presignedRequest.url();
            System.out.println("预签名下载URL: " + presignedUrl.toString());
        }
    }
}

生成预签名URL（PUT上传场景） #

如果需要让用户通过预签名URL上传文件到S3，用这个示例：

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Presigner;
import software.amazon.awssdk.services.s3.model.PutObjectRequest;
import software.amazon.awssdk.services.s3.model.PresignedPutObjectRequest;
import java.net.URL;
import java.time.Duration;

public class GeneratePresignedUrlForPut {
    public static void main(String[] args) {
        String bucketName = "your-bucket-name";
        String objectKey = "path/to/upload/object.txt";
        Region region = Region.US_EAST_1;

        try (S3Presigner presigner = S3Presigner.builder()
                .region(region)
                .build()) {

            PutObjectRequest putObjectRequest = PutObjectRequest.builder()
                    .bucket(bucketName)
                    .key(objectKey)
                    .build();

            PresignedPutObjectRequest presignedRequest = presigner.presignPutObject(r -> r
                    .signatureDuration(Duration.ofHours(1))
                    .putObjectRequest(putObjectRequest));

            URL presignedUrl = presignedRequest.url();
            System.out.println("预签名上传URL: " + presignedUrl.toString());

            // 额外提示：用户可以用这个URL直接发起PUT请求上传文件，比如用curl：
            // curl -X PUT -T "local-file.txt" "presigned-url-here"
        }
    }
}

关键注意事项 #

• 资源清理：S3Presigner是需要关闭的资源，一定要用try-with-resources语法，避免连接泄漏
• 有效期设置：signatureDuration可以根据需求调整，最长不能超过7天（AWS的限制）
• 权限问题：生成预签名URL的IAM账号必须拥有对应的S3操作权限（比如s3:GetObject或s3:PutObject）
• 区域匹配：一定要确保S3Presigner的区域和你的桶所在区域一致，否则会报错

内容的提问来源于stack exchange，提问作者luanlucas