Top 10 Spring Boot Interview Questions You Need to Know

1. What is Spring Boot, and how does it differ from the traditional Spring Framework?

• Spring Boot is a powerful framework built on top of the traditional Spring Framework, designed to simplify and streamline the process of creating stand-alone, production-grade Spring-based applications. Unlike the traditional Spring Framework, which requires manual configuration, Spring Boot offers auto-configuration, making it easier to set up and deploy applications with minimal hassle.

2. What are the key features of Spring Boot?

Some key features of Spring Boot include:

• Auto-configuration: Spring Boot automatically configures application components based on the dependencies present in the classpath.
• Starter dependencies: Spring Boot provides a range of “starter” dependencies that encapsulate sets of common libraries, making it easier to add functionality to your application.
• Embedded servers: Spring Boot supports embedding servlet containers like Tomcat, Jetty, and Undertow, allowing you to run applications as standalone JAR files.
• Production-ready metrics: Spring Boot provides built-in support for monitoring, health checks, and metrics, making applications production-ready out of the box.

3 . How does Spring Boot support externalized configuration?

Spring Boot supports externalized configuration through properties files, YAML files, environment variables, and command-line arguments. By externalizing configuration, you can customize application behavior without modifying the code, making it easier to deploy applications across different environments.

4. What is Spring Boot Actuator, and what are its main features?

Spring Boot Actuator is a subproject of Spring Boot that provides production-ready features to help monitor and manage your application. Some main features of Spring Boot Actuator include:

• Health checks: Provides insights into the health of your application, including database connectivity, disk space, and custom health indicators.
• Metrics: Captures and exposes various metrics about your application, such as request latency, JVM memory usage, and garbage collection statistics.
• Auditing: Tracks and exposes auditing information, such as HTTP requests, environment details, and application startup/shutdown events.

5. How does Spring Boot handle database connectivity?

Spring Boot simplifies database connectivity by providing auto-configuration support for popular databases like MySQL, PostgreSQL, and MongoDB. You can configure data source properties in the application.properties or application.yml file, and Spring Boot will automatically configure the data source bean based on those properties.

6. What is Spring Boot’s embedded servlet container, and how does it work?

Spring Boot’s embedded servlet container allows you to package your application as an executable JAR file with an embedded servlet container (such as Tomcat, Jetty, or Undertow) included. When you run the JAR file, the embedded servlet container starts automatically, and your application becomes accessible via HTTP requests.

7. How does Spring Boot support RESTful web services?

Spring Boot provides robust support for building RESTful web services using Spring MVC. You can use annotations like @RestController and @RequestMapping to create REST endpoints, and Spring Boot will handle content negotiation, request mapping, and response serialization automatically.

8. What is Spring Boot’s testing support, and how do you write unit tests for Spring Boot applications?

Spring Boot provides comprehensive testing support through the Spring Boot Test module. You can write unit tests for your Spring Boot applications using tools like JUnit and Mockito, leveraging features like @SpringBootTest, @MockBean, and @AutoConfigureMockMvc to test various components in isolation or in integration with the Spring context.

9. How does Spring Boot handle security?

Spring Boot provides robust security features through the Spring Security framework. You can configure security settings using annotations like @EnableWebSecurity and @EnableGlobalMethodSecurity, and Spring Boot will handle authentication, authorization, and session management for your application.

10. What are some best practices for deploying Spring Boot applications in production?

• Some best practices for deploying Spring Boot applications in production include:
• Package applications as executable JAR files or Docker containers for easy deployment.
• Use environment-specific configuration files to manage settings across different environments.
• Implement health checks and metrics to monitor application health and performance.
• Secure sensitive information such as database credentials and API keys using environment variables or encrypted properties files.
• Implement logging and monitoring to track application behavior and diagnose issues in production.

By familiarizing yourself with these interview questions and their answers, you’ll be well-equipped to demonstrate your expertise in Spring Boot and impress potential employers. Remember to not only memorize the answers but also understand the underlying concepts and principles behind them. With dedication and practice, you’ll be on your way to acing your Spring Boot interviews and advancing your career in Java development.

Happy Coding !