eBook – Guide Spring Cloud – NPI EA (cat=Spring Cloud)
eBook – Mockito – NPI EA (tag = Mockito)
👁 announcement - icon
Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
👁 announcement - icon
Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.
Get started with understanding multi-threaded applications with our Java Concurrency guide:
eBook – Reactive – NPI EA (cat=Reactive)
👁 announcement - icon
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
eBook – Java Streams – NPI EA (cat=Java Streams)
👁 announcement - icon
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
eBook – Jackson – NPI EA (cat=Jackson)
eBook – HTTP Client – NPI EA (cat=Http Client-Side)
eBook – Maven – NPI EA (cat = Maven)
eBook – Persistence – NPI EA (cat=Persistence)
eBook – RwS – NPI EA (cat=Spring MVC)
Course – LS – NPI EA (cat=Jackson)
👁 announcement - icon
Get started with Spring and Spring Boot, through the Learn Spring course:
>> LEARN SPRINGCourse – RWSB – NPI EA (cat=REST)
👁 announcement - icon
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Course – LSS – NPI EA (cat=Spring Security)
👁 announcement - icon
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
Course – LSD – NPI EA (tag=Spring Data JPA)
👁 announcement - icon
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
Partner – Moderne – NPI EA (cat=Spring Boot)
👁 announcement - icon
Refactor Java code safely — and automatically — with OpenRewrite.
Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.
Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.
Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.
Course – LJB – NPI EA (cat = Core Java)
In this quick article, we’re going to explore the AWS support provided in the Spring Cloud platform – focusing on S3.
Content Series:
This article is part of a series: • Spring Cloud AWS – S3 (current article)
• Spring Cloud AWS – EC2• Spring Cloud AWS – RDS
• Spring Cloud AWS – Messaging Support
1. Simple S3 Download
Let’s start by easily accessing files stored on S3:
@Autowired
ResourceLoader resourceLoader;
public void downloadS3Object(String s3Url) throws IOException {
Resource resource = resourceLoader.getResource(s3Url);
File downloadedS3Object = new File(resource.getFilename());
try (InputStream inputStream = resource.getInputStream()) {
Files.copy(inputStream, downloadedS3Object.toPath(),
StandardCopyOption.REPLACE_EXISTING);
}
}2. Simple S3 Upload
We can also upload files:
public void uploadFileToS3(File file, String s3Url) throws IOException {
WritableResource resource = (WritableResource) resourceLoader
.getResource(s3Url);
try (OutputStream outputStream = resource.getOutputStream()) {
Files.copy(file.toPath(), outputStream);
}
}3. S3 URL Structure
The s3Url is represented using the format:
s3://<bucket>/<object>For example, if a file bar.zip is in the folder foo on a my-s3-bucket bucket, then the URL will be:
s3://my-s3-bucket/foo/bar.zipAnd, we can also download multiple objects at once using ResourcePatternResolver and the Ant-style pattern matching:
private ResourcePatternResolver resourcePatternResolver;
@Autowired
public void setupResolver(ApplicationContext applicationContext, AmazonS3 amazonS3) {
this.resourcePatternResolver =
new PathMatchingSimpleStorageResourcePatternResolver(amazonS3, applicationContext);
}
public void downloadMultipleS3Objects(String s3Url) throws IOException {
Resource[] allFileMatchingPatten = this.resourcePatternResolver
.getResources(s3Url);
// ...
}
}URLs can contain wildcards instead of exact names.
For example the s3://my-s3-bucket/**/a*.txt URL will recursively look for all text files whose name starts with ‘a‘ in any folder of the my-s3-bucket.
Note that the beans ResourceLoader and ResourcePatternResolver are created at application startup using Spring Boot’s auto-configuration feature.
4. Conclusion
And we’re done – this is a quick and to-the-point introduction to accessing S3 with Spring Cloud AWS.
In the next article of the series, we’ll explore the EC2 support of the framework.
The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
Next »
Spring Cloud AWS – EC2
