Spring Boot Building RESTful Services Questions and Answers

Question 1

A developer needs to create a REST endpoint that returns a `201 Created` status code upon successful creation of a resource, and a response body containing the newly created object. Which approach is most appropriate for this scenario in a Spring Boot controller?

Accepted Answer

Return a `ResponseEntity` object, explicitly setting the status to `HttpStatus.CREATED` and including the object in the body.

Answer

Returning a `ResponseEntity` provides the most control over the HTTP response. It allows you to set the status code, headers, and the body all in one object. While `@ResponseStatus` can set the code, it's less flexible if you need to add custom headers. Throwing an exception is incorrect for a success scenario.

Question 2

What is the primary purpose of including the `spring-boot-starter-hateoas` dependency in a Spring Boot project?

Accepted Answer

To add support for building hypermedia-driven RESTful services by easily creating links to related resources.

Answer

The `spring-boot-starter-hateoas` dependency integrates Spring HATEOAS, a library for creating REST representations that follow the HATEOAS (Hypermedia as the Engine of Application State) principle. Its main feature is to make it easy to add hypermedia links to your API responses, guiding the client on what actions they can take next.

Question 3

A REST service needs to support different versions of its API. A decision is made to include the version number in the URL path (e.g., `/api/v1/products` and `/api/v2/products`). Which of the following API versioning strategies does this describe?

Accepted Answer

URI Path Versioning

Answer

URI Path Versioning is a common strategy where the API version is embedded directly into the URL path. This makes the version explicit and easy for clients to see and use. Other methods include passing the version as a query parameter, in a custom HTTP header, or via the `Accept` header (content negotiation).

Question 4

In a Spring Boot REST application, what is the role of the `@RestControllerAdvice` annotation?

Accepted Answer

To provide global, cross-controller exception handling and other request/response modifications.

Answer

`@RestControllerAdvice` is a specialized `@Component` that allows you to implement centralized exception handling across all `@RestController` classes. Methods within a `@RestControllerAdvice`-annotated class can be annotated with `@ExceptionHandler` to handle specific exceptions thrown by any controller, promoting clean, DRY (Don't Repeat Yourself) error handling logic.

Question 5

A client sends a GET request to a Spring Boot REST endpoint with an `Accept` header of `application/xml`. The corresponding controller method returns a POJO. For the application to correctly serialize the POJO into XML, which dependency is typically required on the classpath?

Accepted Answer

jackson-dataformat-xml

Answer

Spring Boot uses the Jackson library for JSON serialization by default. To enable XML serialization and deserialization, you need to add the `jackson-dataformat-xml` dependency. Once this is on the classpath, Spring Boot's auto-configuration will set up the necessary `XmlMapper` to handle content negotiation for XML.

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Spring Boot Building RESTful Services Questions and Answers