To complete this chapter’s recipes, you will need a computer with any OS (I use Ubuntu on Windows Subsystem for Linux – WSL), an editor such as Visual Studio Code (https://code.visualstudio.com/) or IntelliJ Idea (https://www.jetbrains.com/idea/), and Java OpenJDK 17 or higher.

There are multiple distributions of Java from different vendors – if you already have one installed, you can continue using it; if you need to install one, you can use Eclipse Adoptium distribution (https://adoptium.net/).

If you use Visual Studio Code, I recommend installing Extension Pack for Java (https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-pack) and Spring Boot Extension Pack (https://marketplace.visualstudio.com/items?itemName=vmware.vscode-boot-dev-pack).

If you don’t have a tool to perform HTTP requests, you could use curl (https://curl.se/) or Postman (https://www.postman.com/).

Finally, you can download the complete...

A RESTful API is a standardized way for software components to communicate over the internet using HTTP methods and URLs. You should learn it because it’s fundamental for modern web and cloud application development. It promotes scalable, flexible, and stateless communication, enabling developers to design efficient and widely compatible systems. Understanding RESTful APIs is crucial for building and integrating services.

When I was a child I played with football-player cards, exchanging cards that I had multiples of with my friends. My children, some decades later, still play this game. Throughout this chapter, you will create a system to manage a football card-trading game, with teams, players, albums, and cards. In this recipe, you will create a RESTful API exposing Create, Read, Update, and Delete (CRUD) operations on football players.

Getting ready

To create a RESTful API, Spring Boot provides a great tool named Spring Initializr. You can...

In the previous recipe, we created a very simple RESTful API. To develop a RESTful API that provides a positive user experience for its consumers, it is essential to incorporate both standard response codes and a consistent data model. In this recipe, we will enhance the previous RESTful API by returning standard response codes and creating a data model for our players endpoint.

Getting ready

You can use the project generated in the previous recipe or download the sample from the GitHub repository: https://github.com/PacktPublishing/Spring-Boot-3.0-Cookbook/.

You can find the code to start this exercise in the chapter1/recipe1-2/start folder.

How to do it...

In this recipe, we will create a folder structure to contain different types of classes for our project. We will define a data model to expose in our RESTful API, along with a service to provide the operations needed by the API.

Note that all of the content...

In the previous recipe, we enhanced our RESTful API by using complex data structures. However, the application was not able to manage some common errors or return standard response codes. In this recipe, l we will enhance the previous RESTful API by managing common errors and returning consistent response codes following the standards.

Getting ready

You can use the project generated in the previous recipe or download the sample from the GitHub repository at https://github.com/PacktPublishing/Spring-Boot-3.0-Cookbook/.

You can find the code to start this exercise in the chapter1/recipe1-3/start folder.

How to do it...

In this recipe, we will modify the RESTful API created in the previous recipe to handle the exceptions that can be raised by our application and we’ll return the most appropriate HTTP response code.

All content created in the following steps will be under the src/main/java/com/packt/football folder or one of the...

Testing the application manually can be tiring, especially when dealing with challenging scenarios that are hard to validate. Additionally, it lacks scalability in terms of development productivity. Hence, I highly recommend applying automated testing.

By default, Spring Boot includes the Testing starter that provides the basic components for unit and integration testing. In this recipe, we’ll learn how to implement a unit test for our RESTful API.

Getting ready

In this recipe, we’ll create unit tests for the RESTful API created in the previous recipe. I prepared a working version in case you haven’t completed it yet. You can find it in the book’s GitHub repository at https://github.com/PacktPublishing/Spring-Boot-3.0-Cookbook/. You can find the code to start this recipe in the chapter1/recipe1-4/start folder.

How to do it...

Let’s add some tests to our RESTful API that will validate our application whenever we...

Now that we have a RESTful API, we can create a consumer application. We could create an application and just perform HTTP requests. That would require that we provide the consumers with the source code of our application and that they understand it. But what if they are developing their application in a different language and they don’t know Java and Spring Boot? For this reason, OpenAPI was created. OpenAPI is a standard to document RESTful APIs and can be used to generate client applications. It’s widely adopted and is supported by different languages and frameworks. Spring Boot’s support for OpenAPI is excellent.

In this recipe, we’ll learn how to add OpenAPI support to our RESTful API and consume it using the tools provided by OpenAPI.

Getting ready

In this recipe, we will enhance the RESTful API created in the previous recipe. If you haven’t completed the previous recipe, you can find a working...

Now that we have a RESTful API and it’s properly documented, we can create a consumer application. There are many tools to generate the client code from the OpenAPI specification, but in this project, we will create the client code manually for learning purposes.

Getting ready

We will enhance the RESTful API created in the previous recipe. If you haven’t completed that yet, you can find a working version in the book’s GitHub repo at https://github.com/PacktPublishing/Spring-Boot-3.0-Cookbook.

You can find the code to start this exercise in the chapter1/recipe1-6/start folder.

We will create a new Spring Boot application using the Spring Initializr tool again (https://start.spring.io).

How to do it...

We’ll create a Spring Boot application consuming the Football RESTful API created in the previous recipe:

1. First, we’ll create a new Spring Boot application...

In this recipe, we’ll use a new component introduced in Spring Framework 6.1 and available in Spring Boot since version 3.2. In the previous recipe, we created a FeignClient by creating an interface in the client application and defining the same methods available in the target service. By using the RestClient component, we will have a fluent API that offers an abstraction over HTTP libraries. It allows converting from Java objects to HTTP requests, and the other way round, the creation of objects from the HTTP responses.

Getting ready

We will enhance the RESTful API created in the Using OpenAPI to document our RESTful API recipe. If you haven’t completed it yet, you can find a working version in the book’s GitHub repo at https://github.com/PacktPublishing/Spring-Boot-3.0-Cookbook.

You can find the code to start this exercise in the chapter1/recipe1-7/start folder.

We will...

The main drawback of using a remote service as we did in the previous recipes is that you need the remote service running when you test your client application. To tackle this scenario, you can mock a remote server. By mock, I mean simulating the behavior of a component or service, in this case, the remote service.

Mocking a remote dependency in a test can be useful for several reasons. One of the main reasons is that it allows you to test your code in isolation, without having to worry about the behavior of the remote dependency. This can be especially useful if the remote dependency is unreliable or slow, or if you want to test your code in different scenarios that are difficult to reproduce with the remote dependency.

In this recipe, we’ll learn how to use Wiremock to mock the remote Football service in our Albums application during the testing execution.

Getting ready

In this recipe, we’ll create the tests for the application we built...