Top 25 Spring Boot Interview Questions with Answers

Top 25 Spring Boot Interview Questions with Answers:

1. What is Spring Boot?

Ans. Spring Boot is an open-source Java-based framework used for building microservices and web applications. It is designed to simplify the process of creating production-ready applications.

2. What are the advantages of using Spring Boot?

Some of the advantages of using Spring Boot are:

• Reduced development time
• Simplified configuration
• Improved productivity
• Easy integration with third-party libraries
• Reduced boilerplate code

3. What is the difference between Spring and Spring Boot?

Spring is a comprehensive framework that provides a wide range of features for building Java applications. Spring Boot is a subset of the Spring framework that focuses on simplifying the development of Spring-based applications.

4. What is the role of the SpringApplication class in Spring Boot?

The SpringApplication class is used to bootstrap a Spring Boot application. It sets up the application context, loads the configuration, and starts the application.

5. How does Spring Boot simplify configuration?

Spring Boot uses sensible defaults and auto-configuration to simplify configuration. It automatically configures many aspects of the application based on the classpath and configuration files.

6. What is the role of the @SpringBootApplication annotation?

The @SpringBootApplication annotation is used to mark the main class of a Spring Boot application. It combines three other annotations – @Configuration, @EnableAutoConfiguration, and @ComponentScan.

7. What is the difference between @Component, @Service, and @Repository annotations in Spring Boot?

@Component is a generic stereotype annotation used for any Spring-managed component. @Service is used to mark a class as a service layer component, while @Repository is used to mark a class as a data access layer component.

8. What is the role of the @Autowired annotation in Spring Boot?

The @Autowired annotation is used to inject dependencies into a Spring-managed component. It tells Spring to find a matching component from the application context and inject it into the current component.

9. What is the purpose of the application.properties file in Spring Boot?

The application.properties file is used to configure the application properties. It can be used to set properties such as server port, database configuration, logging levels, etc.

10. What is the difference between @RequestMapping and @GetMapping annotations in Spring Boot?

@RequestMapping is a generic annotation used to map a URL to a controller method. @GetMapping is a shortcut for @RequestMapping(method = RequestMethod.GET) used specifically for GET requests.

11. What is the difference between @RequestParam and @PathVariable annotations in Spring Boot?

@RequestParam is used to map query parameters from a request to controller method parameters. @PathVariable is used to map dynamic parts of a URL to controller method parameters.

12. What is the role of Spring Data JPA in Spring Boot?

Spring Data JPA is a library that provides a set of abstractions for working with relational databases. It allows developers to write repository interfaces that can be used to perform common CRUD operations.

13. What is the role of the @Transactional annotation in Spring Boot?

The @Transactional annotation is used to mark a method as transactional. It tells Spring to create a transaction for the method and roll back the transaction if an exception is thrown.

14. What is Spring Security in Spring Boot?

Spring Security is a library that provides authentication, authorization, and other security features for Spring-based applications. It allows developers to secure their applications at the HTTP level or method level.

15. What is the role of the @Secured annotation in Spring Security?

The @Secured annotation is used to apply security to a controller method. It checks whether the current user has the required roles or authorities to access the method.

16. What is the difference between a filter and an interceptor in Spring Boot?

A filter is a component that is executed before or after a request is processed by a controller method. An interceptor is a component.

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Spring boot interview questions for experienced developers

1. How do you optimize the performance of a Spring Boot application?

There are several ways to optimize the performance of a Spring Boot application, such as:

• Caching frequently accessed data
• Optimizing database queries
• Using asynchronous processing for long-running tasks
• Using connection pooling to reduce the overhead of database connections
• Tuning JVM parameters

2. What is the role of Spring Boot Actuator?

Spring Boot Actuator is a library that provides insight into the running Spring Boot application. It exposes various endpoints that can be used to monitor and manage the application, such as health checks, metrics, and shutdown.

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3. How do you implement authentication and authorization in a Spring Boot application?

Authentication and authorization can be implemented using Spring Security. Spring Security provides a range of authentication and authorization options, such as form-based authentication, JWT authentication, and role-based access control.

4. How do you handle exceptions in a Spring Boot application?

Exceptions can be handled using Spring’s exception handling mechanism. The @ControllerAdvice annotation can be used to define a global exception handler for the application. Custom exception classes can also be created to handle specific exceptions.

5. How do you implement logging in a Spring Boot application?

Logging can be implemented using a logging framework such as Log4j or Logback. Spring Boot includes a logging framework called Logback by default. Logging can be configured using the application.properties file.

6. What is the role of Spring Boot Test in testing a Spring Boot application?

Spring Boot Test provides a range of utilities for testing Spring Boot applications. It includes support for testing web applications, database testing, and integration testing.

7. How do you implement a database connection pool in a Spring Boot application?

A database connection pool can be implemented using a library such as HikariCP or Tomcat JDBC. The connection pool can be configured using the application.properties file.

8. How do you handle cross-cutting concerns such as logging, security, and transactions in a Spring Boot application?

Cross-cutting concerns can be handled using Spring AOP (Aspect-Oriented Programming). Spring AOP allows developers to define aspects that can be applied to multiple methods or classes.

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9. How do you implement distributed tracing in a Spring Boot application?

Distributed tracing can be implemented using a library such as Zipkin or Jaeger. These libraries provide a way to trace requests as they pass through a distributed system.

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10. How do you implement caching in a Spring Boot application?

Caching can be implemented using Spring Cache. Spring Cache provides a way to cache frequently accessed data, such as database queries or API responses. The caching mechanism can be configured using annotations such as @Cacheable and @CacheEvict.