Spring Framework Case Studies & Practical Application 5

Question 1

A Spring Boot REST API must rate-limit requests per API key without external infrastructure. Which Spring component provides the most straightforward insertion point?

Accepted Answer

A HandlerInterceptor or OncePerRequestFilter that checks a per-key counter before the controller executes

Answer

A servlet Filter or HandlerInterceptor runs before the controller and can short-circuit the request with a 429 response if the rate limit is exceeded.

Question 2

A Spring application uses RabbitMQ via Spring AMQP. Messages are occasionally lost when the broker restarts. What configuration prevents message loss?

Accepted Answer

Declare queues and exchanges as durable and publish messages as persistent (deliveryMode=2)

Answer

Durable queues survive broker restarts, and persistent messages (deliveryMode=2) are written to disk, together ensuring no messages are lost on broker restart.

Question 3

A company migrates from Spring Boot 2 to Spring Boot 3. Their application uses javax.* imports throughout. What is the required code change?

Accepted Answer

Replace all javax.* imports with jakarta.* imports, as Spring Boot 3 is based on Jakarta EE 9+

Answer

Spring Boot 3 is built on Jakarta EE 9+, which replaced the javax.* namespace with jakarta.*; all imports must be updated manually or via migration tools.

Question 4

A Spring Security application must allow users to log in with Google OAuth2 and also with a username/password. Which configuration approach handles both?

Accepted Answer

Use a single SecurityFilterChain with both formLogin() and oauth2Login() configured

Answer

Spring Security's fluent DSL allows combining formLogin() and oauth2Login() in a single HttpSecurity configuration, with each flow handled by its dedicated filter chain entry.

Question 5

A Spring Boot application must expose a custom metric — the number of pending orders — to a Prometheus scrape endpoint. What is the recommended approach?

Accepted Answer

Register a MeterBinder bean that uses a Gauge to read the pending order count from the repository

Answer

Implementing MeterBinder and registering a Gauge with Micrometer allows the metric to appear on /actuator/prometheus automatically with proper lifecycle management.

Spring Framework Practice Test

Spring Framework Practice Test

Spring Framework Case Studies & Practical Application 5