Spring Boot 3.0 Cookbook

This text explains how to create a basic RESTful API using Spring Boot for managing football player data. It walks through setting up a project with Spring Initializr, creating a PlayerController with CRUD operations (Create, Read, Update, Delete) using HTTP methods (GET, POST, PUT, DELETE), and testing the API endpoints with curl commands. The explanation covers how Spring Boot and annotations like @RestController, @RequestMapping, @GetMapping, @PostMapping, @PutMapping, @DeleteMapping, @PathVariable, and @RequestBody work together to handle HTTP requests and map them to specific methods. It also touches on the importance of HTTP status codes in RESTful API design and provides links for further learning on API design best practices.

This recipe focuses on enhancing a basic RESTful API by incorporating standard response codes and a consistent data model. It involves creating a Player data model, custom exceptions (AlreadyExistsException, NotFoundException), and a FootballService to manage player data operations (listing, retrieving, adding, updating, and deleting players). The PlayerController is then modified to utilize the FootballService and expose the Player data model through REST endpoints. The recipe also touches on how Spring Boot handles serialization and HTTP status codes by default, and briefly explains Java records and Spring’s dependency injection using @Service.

This recipe focuses on enhancing a RESTful API to handle common errors and return consistent HTTP response codes. It demonstrates how to manage exceptions like NotFoundException and AlreadyExistsException using @ExceptionHandler and @ResponseStatus annotations within the PlayerController. This ensures that appropriate HTTP status codes (e.g., 404 for "Not Found", 400 for "Bad Request") are returned to the client, adhering to RESTful API semantics. The recipe also briefly touches on alternative approaches, such as using ResponseEntity for explicit status code control and @ControllerAdvice for global exception handling across all controllers.

This guide explains how to implement unit tests for a RESTful API in Spring Boot using the spring-boot-starter-test dependency. It walks through creating a test class, mocking the service layer, and using MockMvc to simulate HTTP requests. The example demonstrates testing both successful API calls and error handling (e.g., resource not found). It also briefly explains the annotations and classes used, such as @WebMvcTest, @MockBean, given, and MockMvc, and introduces the Arrange-Act-Assert (AAA) testing principle.

This document explains how to add OpenAPI support to a Spring Boot RESTful API. OpenAPI is a standard for documenting RESTful APIs and generating client applications. The steps involve adding the org.springdoc:springdoc-openapi-starter-webmvc-ui dependency to the project’s pom.xml file. Once added, the application can be run, and the API documentation can be accessed in JSON format at http://localhost:8080/v3/api-docs. A user-friendly interface for interacting with the API is available at http://localhost:8080/swagger-ui/index.html. This UI allows users to execute API operations and view the data model. The OpenAPI dependency examines the application at runtime to generate the API description, which includes endpoints, HTTP methods, parameters, responses, and data schemas.

This document describes how to create a Spring Boot application that consumes a RESTful API using Feign, a declarative web service client. It walks through the steps of setting up a new Spring Boot project with Spring Web and OpenFeign dependencies, defining a Player record and a FootballClient interface to specify the API endpoint, creating an AlbumsController to use the FootballClient to retrieve player data, and enabling Feign clients in the main application class. The application is then run on port 8081 to avoid conflicts with the API running on port 8080, and tested using curl. The document also explains how Feign simplifies HTTP requests and mentions alternative tools for generating client code from OpenAPI specifications.

This recipe demonstrates how to use the RestClient component in Spring Framework 6.1 (Spring Boot 3.2+) to consume a RESTful API. Instead of creating a FeignClient with an interface, RestClient offers a fluent API for making HTTP requests and handling responses.

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This document explains how to use Wiremock to mock a remote "Football" service in a Spring Boot Albums application during testing. It details the process of adding the Wiremock dependency, creating a test class for the FootballClientService, setting up a Wiremock server, and writing a test to validate the getPlayer method. The test involves arranging the result of the remote service, calling the getPlayer method, and validating the results. The document also explains how Wiremock works and provides a link to the Wiremock project web page for more information.