Spring in Action

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After nearly 15 years of working with Spring and having written five editions of this book (not to mention Spring Boot in Action), you’d think that it’d be hard to come up with something exciting and new to say about Spring when writing the preface for this book. But nothing could be further from the truth! Chapter 14 shows how to centralize application configuration in a configuration server that shares configuration across multiple microservices. This book contains many examples of source code both in numbered listings and inline with normal text. In both cases, source code is formatted in a fixed-width font like this to separate it from ordinary text. Sometimes code is also in bold to highlight code that has changed from previous steps in the chapter, such as when a new feature adds to an existing line of code. Nearly 100,000 developers have used the book version to learn Spring! Spring in Action requires a working knowledge of Java.

Finally, the build specification ends with the Spring Boot plugin. This plugin performs a few important functions: In addition to the new reactive programming features of Spring 5, Spring Boot 2 now provides even more autoconfiguration support than ever before as well as a completely reimagined Actuator for peeking into and manipulating a running application. Any non-trivial application is composed of many components, each responsible for its own piece of the overall application functionality, coordinating with the other application elements to get the job done. When the application is run, those components somehow need to be created and introduced to each other.Spring Boot autoconfiguration has dramatically reduced the amount of explicit configuration (whether with XML or Java) required to build an application. In fact, by the time you finish the example in this chapter, you’ll have a working Spring application that has only a single line of Spring configuration code! application.properties—This file is initially empty, but offers a place where you can specify configuration properties. We’ll tinker with this file a little in this chapter, but I’ll postpone a detailed explanation of configuration properties to chapter 5. To get started with a new Spring project in Spring Tool Suite, go to the File menu and select New, and then Spring Starter Project. Figure 1.2 shows the menu structure to look for.

Craig Walls is a principal software engineer at Pivotal, a popular author, an enthusiastic supporter of Spring Framework, and a frequent conference speaker.It provides a Maven goal that enables you to run the application using Maven. You’ll try out this goal in section 1.3.4. Spring in Action, 5th edition is for Java developers who want to get started with Spring Boot and the Spring Framework as well as for seasoned Spring developers who want to go beyond the basics and learn the newest features of Spring. How this book is organized: a roadmap But enough of this chitchat, yakety-yak, and flimflam. This book’s title includes the phrase in action, so let’s get moving, and you can start writing your first application with Spring. 1.2. Initializing a Spring application Spring Framework makes life easier for Java developers. New features in Spring 5 bring its productivity-focused approach to microservices, reactive development, and other modern application designs. With Spring Boot now fully integrated, you can start even complex projects with minimal configuration code. And the upgraded WebFlux framework supports reactive apps right out of the box!