In modern cloud-native applications, file storage is a key requirement. Whether you’re building a media-rich web platform, a document archival system, or simply storing user profile pictures, object storage systems like Amazon S3 offer scalable and reliable solutions.
This blog focuses on AWS S3 integration with Spring Boot, especially when handling secure file transfers using pre-signed URLs. You’ll learn when to use signed URLs, how they differ from regular uploads, and how to implement them cleanly in your application.
Let’s break it down systematically and explore how AWS S3 integration can improve the scalability and performance of your cloud-native applications.
Amazon S3 (Simple Storage Service) is a scalable, high-durability object storage platform provided by AWS. It allows applications to store and retrieve any amount of data, at any time, from anywhere on the web. As a foundation for AWS S3 integration, S3 offers powerful features ideal for application storage needs:
▪️Unlimited storage
▪️99.999999999% (11 9’s) of durability
▪️Fine-grained access control via IAM
▪️Lifecycle policies, versioning, and encryption
S3 stores files as objects inside buckets, with each object assigned a unique key.
To build a secure and scalable setup, let’s create a Spring Boot application with AWS S3 integration.
▪️Java 17+
▪️Spring Boot 3+
▪️AWS Java SDK v1, reliable for S3 tasks
In your pom.xml, add:
<!-- Spring Boot Web -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- AWS SDK for S3 -->
<dependency>
<groupId>com.amazonaws</groupId>
<artifactId>aws-java-sdk-s3</artifactId>
<version>1.12.670</version>
</dependency>
<!-- Lombok (Optional) -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>Use application.properties:
aws.region=ap-south-1
aws.accessKey=YOUR_ACCESS_KEY
aws.secretKey=YOUR_SECRET_KEY
aws.s3.bucket=my-app-bucket
aws.s3.expiration.minutes=10This is critical for enabling AWS S3 integration in your backend securely and programmatically.
Normally, file uploads flow like this:
Client → Backend → S3This can overload your server, especially for large files.
Pre-signed URLs allow a better approach:
Client → S3 (direct) ← signed URL from BackendThe server only signs the request and delegates the actual upload/download to the client. This improves scalability, performance, and cost-efficiency.
▪️Client requests an upload URL The client sends the desired filename and content type to your Spring Boot backend.
▪️Server generates a signed PUT URL Backend creates a pre-signed URL using AWS SDK and returns it.
▪️Client uploads directly to S3 Using Http PUT, the file is uploaded to S3 using the signed URL.
▪️(Optional) Client informs server Post-upload, the client can notify the server of a successful upload.
▪️Client requests a download URL Client sends the object key (filename or ID).
▪️Server creates signed GET URL A pre-signed URL with an expiration time is generated.
▪️Client downloads the file Client accesses the file directly from S3 without burdening your server.
This efficient workflow is a key benefit of AWS S3 integration in scalable systems.
@Service
public class S3Service {
@Value("${aws.region}") private String region;
@Value("${aws.accessKey}") private String accessKey;
@Value("${aws.secretKey}") private String secretKey;
@Value("${aws.s3.bucket}") private String bucket;
@Value("${aws.s3.expiration.minutes}") private int expirationMinutes;
private AmazonS3 s3Client;
@PostConstruct
public void init() {
BasicAWSCredentials creds = new BasicAWSCredentials(accessKey, secretKey);
this.s3Client = AmazonS3ClientBuilder.standard()
.withRegion(region)
.withCredentials(new AWSStaticCredentialsProvider(creds))
.build();
}
public String generateUploadUrl(String fileName) {
Date expiration = Date.from(Instant.now().plus(Duration.ofMinutes(expirationMinutes)));
GeneratePresignedUrlRequest request = new GeneratePresignedUrlRequest(bucket, fileName)
.withMethod(HttpMethod.PUT)
.withExpiration(expiration);
return s3Client.generatePresignedUrl(request).toString();
}
public String generateDownloadUrl(String fileName) {
Date expiration = Date.from(Instant.now().plus(Duration.ofMinutes(expirationMinutes)));
GeneratePresignedUrlRequest request = new GeneratePresignedUrlRequest(bucket, fileName)
.withMethod(HttpMethod.GET)
.withExpiration(expiration);
return s3Client.generatePresignedUrl(request).toString();
}
}| Feature | Normal File Upload | Pre-Signed URL Upload |
|---|---|---|
Upload Flow | Client → Server → S3 | Client → S3 (via URL from Server) |
Backend Load | High (server handles file stream) | Minimal (URL generation only) |
Security | Backend-authenticated | Signed URLs with expiration |
Performance | Slower for large files | Faster and direct |
Scalability | Bottleneck at server | Highly scalable |
Client Complexity | Simple | Needs PUT/GET implementation |
Cost Efficiency | More server resources | Optimized storage cost |
▪️Offloads large file handling from backend
▪️Improves performance for clients
▪️Secure and temporary access to files
▪️Ideal for mobile apps and frontend-heavy platforms
▪️Slightly more complex for frontend developers
▪️Can be abused if URL is leaked (use short expiry times)
▪️Requires careful logging and monitoring
▪️Use short-lived expiration (5–10 minutes)
▪️Don’t expose S3 bucket names publicly
▪️Consider object-level encryption if storing sensitive data
▪️Monitor access logs and usage
▪️User-uploaded profile images in mobile apps
▪️Video uploads in media platforms
▪️Document storage in enterprise CRMs
▪️IoT sensor logs directly streaming to S3
Across industries, AWS S3 integration supports seamless file handling at scale.
Pre-signed URLs with Amazon S3 allow developers to build highly efficient, scalable, and secure file handling workflows. When combined with Spring Boot, this becomes a robust solution suitable for both startups and enterprise-grade systems.
If you’re building a modern web or mobile app, embracing AWS S3 integration with pre-signed URLs is a future-ready approach.
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