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

Creating a reactive ImageService

The first rule of thumb when building web apps is to keep Spring controllers as light as possible. We can think of them as converters between HTTP traffic and our system.

To do that, we need to create a separate ImageService, as shown here, and let it do all the work:

    public class ImageService { 
      private static String UPLOAD_ROOT = "upload-dir"; 
      private final ResourceLoader resourceLoader; 
      public ImageService(ResourceLoader resourceLoader) { 
        this.resourceLoader = resourceLoader; 

This last Spring service can be described as follows:

  • @Service: This indicates this is a Spring bean used as a service. Spring Boot will automatically scan this class and create an instance.
  • UPLOAD_ROOT: This is the base folder where images will be stored.
  • ResourceLoader: This is a Spring utility class used to manage files. It is created automatically by Spring Boot and injected to our service via constructor...