Book Image

Spring 5.0 By Example

By : Claudio Eduardo de Oliveira
Book Image

Spring 5.0 By Example

By: Claudio Eduardo de Oliveira

Overview of this book

With growing demands, organizations are looking for systems that are robust and scalable. Therefore, the 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 book has three parts, where each one covers the building of a comprehensive project in Java and Spring. In the first part, you will construct a CMS Portal using Spring's support for building REST APIs. You will also learn to integrate these APIs with AngularJS and later develop this application in a reactive fashion using Project Reactor, Spring WebFlux, and Spring Data. In the second part, you’ll understand how to build a messaging application, which will consume the Twitter API and perform filtering and transformations. Here, you will also learn about server-sent events and explore Spring’s support for Kotlin, which makes application development quick and efficient. In the last part, you will build a real microservice application using the most important techniques and patterns such as service discovery, circuit breakers, security, data streams, monitoring, and a lot more from this architectural style. By the end of the book, you will be confident about using Spring to build your applications.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Dedication
Packt Upsell
Contributors
Preface
Index

Spring reactive web clients


This is a pretty new feature which was added in Spring Framework 5. It enables us to interact with HTTP services, using the reactive paradigm.

It is not a replacement for a RestTemplate provided by Spring, however, it is an addition to working with reactive applications. Do not worry, the RestTemplate is an excellent and tested implementation for interaction with HTTP services in traditional applications.

Also, the WebClient implementation supports the text/event-stream mime type which can enable us to consume server events.

Producing WebClient in a Spring Way

Before we start to call the Twitter APIs, we want to create an instance of WebClient in a Spring way. It means we are looking for a way to inject the instance, using the Dependency Injection Pattern.

To achieve this, we can use the @Configuration annotation and create a WebClient instance, using the @Bean annotation to declare the bean for the Spring container. Let's do that:

package springfive.twittergathering...