These starter packages allow us to quickly grab the bits we need to get up and running. Spring Boot starters have become so popular that many other third-party library developers are crafting their own.
The value of this last starter, spring-boot-starter-test , cannot be overstated. With a single line, the most powerful test utilities are at our fingertips, allowing us to write unit tests, slice tests, and full-blown our-app-inside-embedded-Netty tests.
It's why this starter is included in all projects without checking a box on the Spring Initializr site. Now, to get things off the ground, we need to shift focus to the tiny bit of code written for us by the Spring Initializr. Spring Boot uses embedded Netty, so there's no need to install a container on our target machine.
Non-web apps don't even require that. The JAR itself is the new container that allows us to stop thinking in terms of old-fashioned servlet containers. Instead, we think in terms of apps. All these factors add up to maximum flexibility in application deployment.
How does Spring Boot use embedded Netty among other things? As mentioned earlier, it has autoconfiguration, which means that it defines Spring beans based on different conditions. When Spring Boot sees Netty on the classpath, it creates an embedded Netty instance along with several beans to support it. When it spots Spring WebFlux on the classpath, it creates view resolution engines, handler mappers, and a whole host of other beans needed to help us write a web application. This lets us focus writing routes, not doddling around configuring infrastructure.
With Flapdoodle on the classpath as well as the Reactive MongoDB drivers, it spins up an in-memory, embedded MongoDB data store and connects to it with its state-of-the-art drivers. Spring Data MongoDB will cause Spring Boot to craft a MongoOperations bean along with everything else needed to start speaking Mongo Query Language and make it available if we ask for it, letting us focus on defining repositories.
At this stage, we have a running web application, albeit an empty one. There are no custom routes, and no means to handle data. But we can add some real fast. Try it out! By the way, it sure would be handy if the system could detect this change and relaunch automatically, right? That's nice, but since we picked Spring Data MongoDB, how hard would it be to load some sample data and retrieve it from another route? Spoiler alert--Not hard at all.
We can start out by defining a simple Chapter entity to capture book details, as follows:. To interact with this entity and its corresponding collection in MongoDB, we could dig in and start using the autoconfigured MongoOperations supplied by Spring Boot. But why do that when we can declare a repository-based solution? To do this, we'll create an interface defining the operations we need. Check out this simple interface:. With Chapter and ChapterRepository defined, we can now preload the database, as shown in the following code:.
This may not be very elaborate, but this small collection of classes has helped us quickly define a slice of functionality. And, if you'll notice, we spent zero effort configuring JSON converters, route handlers, embedded settings, or any other infrastructure.
We just got things off the ground with an operational application, but that isn't the only killer feature of Spring Boot. Spring Boot comes with a fistful of prebuilt properties. Many of these autoconfigured beans will back off if Boot spots us creating our own.
However, if we define our own MongoClient bean, then Spring Boot will back off and accept ours. This can lead to other components switching off.
But sometimes, we don't need to swap out an entire bean. Instead, we may wish to merely tweak a single property of one of these autoconfigured beans. This preceding changes will cause Spring Boot to launch Netty on port , as shown here:. It will also bump up the log level for package com. While it's handy to externalize configuration settings into property files, it wouldn't be a big advantage if they were only embeddable inside our app's JAR file.
That's why, Spring Boot comes with property override support. The following list shows all the locations from which we can override properties, the first being the highest priority:. For an example of the same overrides in YAML format as our application.
This would do the exact same thing that we already saw with application. The only difference is the formatting. What are the benefits of YAML over properties? If we need to override lots of settings, it avoids duplication of various keys. In this preceding example, the second property, app. This isn't the end of options with property overrides. It's just the beginning. Throughout this book, we'll expand on the options provided by Spring Boot's property support.
We've hacked out a suitable application. Git stats 9 commits. Failed to load latest commit information. View code. About the Book Spring Boot provides a variety of features that address today's business needs along with today's scalable requirements. Instructions and Navigation All of the code is organized into folders. About Learning Spring Boot 2. MIT License. Releases No releases published. Once you are familiar with the basics, you will explore advanced things like customizing auto-configuration to meet your expectation.
After that, the book explores the microservice and cloud landscapes by introducing key Spring Boot tools and services. In short, the book covers everything you need to know for developing Spring-based Java microservices applications, starting from development to testing and deployment. That's all for now regarding the best books to learn Spring Boot and Spring Cloud. These are the two leading Java frameworks for developing cloud-based Java applications. These books will not only help you to learn the basics, but they also gives you the hands-on experience you need to create and deploy your own Java application on cloud.
These books should be enough to learn cloud-based Java development, but if you need more assistance, you can also refer to Master MicroService development with Spring Boot for a more instructor-led learning. Thanks for reading this article!
If you like these Spring Boot and Spring Cloud books, please share them with your friends and colleagues. If you have any questions or feedback, drop a note in the comments below.
See the original article here. Thanks for visiting DZone today,. Edit Profile. Sign Out View Profile. Over 2 million developers have joined DZone. Looking to learn more about Spring Boot and Spring Cloud? Then check out these five books to help get you started! Like Filled with examples, you will gain hands-on experience of every area that Spring tackles. Downloading the example code for this book.
Download Example Code. Learn algorithms for solving classic computer science problems with this concise guide covering everything from fundamental …. Even bad code can function. But if code isn't clean, it can bring a development organization …. Explore the reactive system and create efficient microservices with Spring Boot 2.
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