Book Image

Developing Java Applications with Spring and Spring Boot

By : Claudio Eduardo de Oliveira, Greg L. Turnquist, Alex Antonov
Book Image

Developing Java Applications with Spring and Spring Boot

By: Claudio Eduardo de Oliveira, Greg L. Turnquist, Alex Antonov

Overview of this book

Spring Framework has become the most popular framework for Java development. It not only simplifies software development but also improves developer productivity. This book covers effective ways to develop robust applications in Java using Spring. The course is up made of three modules, each one having a take-away relating to building end-to-end java applications. The first module takes the approach of learning Spring frameworks by building applications.You will learn to build APIs and integrate them with popular fraemworks suh as AngularJS, Spring WebFlux, and Spring Data. You will also learn to build microservices using Spring's support for Kotlin. You will learn about the Reactive paradigm in the Spring architecture using Project Reactor. In the second module, after getting hands-on with Spring, you will learn about the most popular tool in the Spring ecosystem-Spring Boot. You will learn to build applications with Spring Boot, bundle them, and deploy them on the cloud. After learning to build applications with Spring Boot, you will be able to use various tests that are an important part of application development. We also cover the important developer tools such as AMQP messaging, websockets, security, and more. This will give you a good functional understanding of scalable development in the Spring ecosystem with Spring Boot. In the third and final module, you will tackle the most important challenges in Java application development with Spring Boot using practical recipes. Including recipes for testing, deployment, monitoring, and securing your applications. This module will also address the functional and technical requirements for building enterprise applications. By the end of the course you will be comfortable with using Spring and Spring Boot to develop Java applications and will have mastered the intricacies of production-grade applications.
Table of Contents (34 chapters)
Title Page - Courses
Copyright and Credits - Courses
Packt Upsell - Courses

Pulling data through a Mono/Flux and chain of operations

We have wired up a repository to interface with MongoDB through Spring Data. Now we can start hooking it into our ImageService.

The first thing we need to do is inject our repository into the service, like this:

    public class ImageService { 
      private final ResourceLoader resourceLoader; 
      private final ImageRepository imageRepository; 
      public ImageService(ResourceLoader resourceLoader, 
       ImageRepository imageRepository) { 
         this.resourceLoader = resourceLoader; 
         this.imageRepository = imageRepository; 

In the previous chapter, we loaded Spring's ResourceLoader. In this chapter, we are adding ImageRepository to our constructor.

Previously, we looked up the names of the existing uploaded files, and constructed a Flux of Image objects. That required coming up with a contrived id value.

Now that we have a real data store, we can simply fetch them...