As the software development industry continues to evolve, Spring Boot remains one of the most sought-after frameworks for building robust and scalable applications. If you’re preparing for a Spring Boot interview in 2025, especially with three years of experience, you’re expected to have a deep understanding of the framework, along with its practical applications.
In this blog post, we’ll explore 10 must-know Spring Boot interview questions and provide detailed answers to help you ace your interview. Additionally, this post is optimized for keywords like “Spring Boot Interview Code Decode,” ensuring it ranks high in search engines.
1. What is Spring Boot and How is it Different from the Spring Framework?
Answer:
Spring Boot is an extension of the Spring Framework designed to simplify the development process by providing default configurations, embedded servers, and opinionated defaults. Unlike the Spring Framework, which requires extensive XML or Java configuration, Spring Boot minimizes boilerplate code through features like:
- Auto-Configuration: Automatically configures beans based on the application’s dependencies.
- Embedded Servers: Comes with Tomcat, Jetty, or Undertow for quick deployment.
- Spring Initializr: A web tool to bootstrap new Spring Boot projects.
For instance, while traditional Spring applications require a web.xml for servlet configuration, Spring Boot eliminates the need for such manual setup.
2. Explain the @SpringBootApplication annotation.
Answer:
The @SpringBootApplication annotation is a special annotation in Spring Boot that combines several important annotations to simplify configuration.
- @Configuration: Marks the class as a source of bean definitions.
- @EnableAutoConfiguration: Enables automatic configuration of beans.
- @ComponentScan: Scans the base package for annotated components like @Controller or @Service.
Interview Tip: Explain how the @SpringBootApplication annotation simplifies configuration and allows you to focus on business logic rather than setup.
3. What are Profiles in Spring Boot, and how do you use them?
Answer:
Profiles in Spring Boot allow developers to define different configurations for various environments, such as development, testing, and production. Profiles can be specified using the spring.profiles.active property in application.properties or application.yml.
Example:
# application-dev.properties
spring.datasource.url=jdbc:mysql://localhost:3306/devdb
# application-prod.properties
spring.datasource.url=jdbc:mysql://prod-db-server:3306/proddbTo activate a profile:
java -Dspring.profiles.active=dev -jar app.jar4. What is the role of Spring Boot Starter dependencies?
Answer:
Spring Boot starters simplify dependency management by bundling commonly used libraries for specific functionalities. For example:
- spring-boot-starter-web: Includes dependencies for building web applications like Spring MVC, Tomcat, and Jackson.
- spring-boot-starter-data-jpa: Bundles Hibernate, JPA, and H2 Database.
Example (pom.xml):
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>This eliminates the need to add individual dependencies manually.
5. How does Spring Boot handle exceptions?
Answer:
Spring Boot provides a global exception-handling mechanism using @ControllerAdvice and @ExceptionHandler annotations.
Example:
@ControllerAdvice
public class GlobalExceptionHandler {
@ExceptionHandler(ResourceNotFoundException.class)
public ResponseEntity<String> handleNotFound(ResourceNotFoundException ex) {
return new ResponseEntity<>(ex.getMessage(), HttpStatus.NOT_FOUND);
}
}This ensures consistent error responses across the application.
6. What is Actuator in Spring Boot?
Answer:
Spring Boot Actuator offers features that help monitor and manage applications in a production environment. It exposes endpoints for health checks, metrics, and other operational information.
Example Endpoints:
- /actuator/health: Shows the application’s health.
- /actuator/metrics: Displays metrics like memory usage and request counts.
To enable Actuator:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>7. How does Spring Boot support Microservices architecture?
Answer:
Spring Boot facilitates microservices development with features like:
- Spring Cloud Integration: Provides tools like Eureka for service discovery and Zuul/Spring Cloud Gateway for API routing.
- Lightweight Design: The embedded server ensures portability and easy deployment.
- Resilience Features: Libraries like Resilience4j for circuit-breaking mechanisms.
Interview Tip: Share examples of how you’ve used Spring Boot for building microservices in real-world projects.
8. Explain the significance of Spring Security in Spring Boot applications.
Answer:
Spring Security works smoothly with Spring Boot to deliver authentication and authorization functionality.
Example: Securing an endpoint:
@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http.authorizeRequests()
.antMatchers("/public/**").permitAll()
.anyRequest().authenticated()
.and()
.httpBasic();
}
}Keywords to mention: OAuth2, JWT, and role-based access control.
9. How can integration testing be done in Spring Boot?
Answer:
Spring Boot simplifies integration testing with @SpringBootTest.
Example:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class ApplicationIntegrationTest {
@Autowired
private TestRestTemplate restTemplate;
@Test
public void testHealthCheck() {
ResponseEntity<String> response = restTemplate.getForEntity("/actuator/health", String.class);
assertEquals(HttpStatus.OK, response.getStatusCode());
}
}Interview Tip: Highlight how integration testing ensures the application’s modules work together seamlessly.
10. What is the importance of Docker and Kubernetes with Spring Boot in 2025?
Answer:
Docker and Kubernetes are essential for deploying Spring Boot applications in containerized environments.
- Docker: Packages the application and its dependencies into a container image.
- Kubernetes: Orchestrates and manages containerized applications at scale.
Example Dockerfile:
FROM openjdk:17-jdk-alpine
COPY target/app.jar app.jar
ENTRYPOINT ["java", "-jar", "app.jar"]Conclusion
By mastering these Spring Boot interview questions and answers, you can confidently demonstrate your expertise and secure your next role in 2025. If you’re looking for more tips, tutorials, or code explanations, visit our YouTube channel Code Decode, where we dive deep into Spring Boot and related technologies.
Stay updated, keep coding, and best of luck with your interviews
