Spring Boot, a project from the Spring Framework, is designed to simplify the development of production-ready applications by providing a suite of pre-configured, out-of-the-box solutions. As the demand for rapid development and microservices architecture increases, Spring Boot has become a staple in the toolkit of Java developers. If you're preparing for a job interview that involves Spring Boot, this guide will help you get ready with some of the most common and challenging questions you might face.
Top Spring Boot Interview Questions and Answers for Freshers
1. What is Spring Boot and its advantages?
Answer:
Spring Boot is an open-source Java-based framework used to create stand-alone, production-grade Spring-based applications. Its advantages include reduced development time, easy deployment, embedded servers, opinionated defaults, and minimal configuration requirements.
2. Explain the key features of Spring Boot.
Answer:
Key features of Spring Boot include:
- Auto-configuration: Automatically configure your Spring application based on the dependencies you have added.
- Standalone: Applications can run without requiring an external server.
- Production-ready: Includes features like health checks, metrics, and externalized configuration.
- Spring Initializr: Provides a web-based tool to generate Spring Boot projects quickly.
3. What is the Spring Initializr?
Answer:
Spring Initializr is a web-based tool that allows developers to create a new Spring Boot project with a selected set of dependencies. It provides a user-friendly interface to generate a project structure that can be directly imported into an IDE.
4. How do you set up a Spring Boot application?
Answer:
To set up a Spring Boot application:
- Use Spring Initializr to generate the project.
- Import the project into your IDE.
- Define the main application class with @SpringBootApplication annotation.
- Add dependencies in the pom.xml or build. gradle file.
- Run the application using the SpringApplication.run() method.
5. What is the use of the @SpringBootApplication annotation?
Answer:
The @SpringBootApplication annotation is a combination of three annotations: @EnableAutoConfiguration, @ComponentScan, and @Configuration. It marks the main class of a Spring Boot application and triggers auto-configuration and component scanning.
Top Spring Boot Interview Questions for Experienced Developers
1. Explain Spring Boot Auto-Configuration.
Answer:
Auto-Configuration is a feature of Spring Boot that automatically configures the application based on the dependencies present on the classpath. It eliminates the need for manual bean configuration by providing sensible defaults and can be customized using application.properties or application.yml files.
2. How can you create a custom starter in Spring Boot?
Answer:
To create a custom starter:
- Create a new Maven or Gradle project.
- Define the dependencies your starter will manage.
- Create auto-configuration classes with @Configuration and @ConditionalOnClass or @ConditionalOnMissingBean annotations.
- Package the project as a JAR and publish it to a Maven repository.
3. What is Spring Boot Actuator, and how do you use it?
Answer:
Spring Boot Actuator provides production-ready features such as monitoring and management of applications. It includes endpoints for health checks, metrics, info, and environment. To use it, add the spring-boot-starter-actuator dependency and configure the endpoints in the application.properties file.
4. How do you handle exceptions in Spring Boot?
Answer:
Exceptions in Spring Boot can be handled using @ControllerAdvice and @ExceptionHandler annotations. @ControllerAdvice is used to define a global exception handler, and @ExceptionHandler is used to handle specific exceptions.
5. What are Spring Profiles, and how do you use them?
Answer:
Spring Profiles allow developers to segregate parts of the application configuration and make it only available in certain environments. You can define beans for different profiles using the @Profile annotation and activate profiles via application.properties or command line arguments.
6. Explain how to secure a Spring Boot application.
Answer:
To secure a Spring Boot application:
- Add the spring-boot-starter-security dependency.
- Configure security settings in the SecurityConfig class by extending WebSecurityConfigurerAdapter.
- Use annotations like @EnableWebSecurity, @PreAuthorize, and @Secured for method-level security.
7. How can you implement caching in Spring Boot?
Answer:
Caching in Spring Boot can be implemented by:
- Adding the spring-boot-starter-cache dependency.
- Enabling caching with @EnableCaching annotation.
- Defining cacheable methods using @Cacheable, @CachePut, and @CacheEvict annotations.
- Configuring cache properties in application.properties.
8. What is Spring Cloud, and how does it relate to Spring Boot?
Answer:
Spring Cloud provides tools for building distributed systems and microservices. It integrates seamlessly with Spring Boot to offer features like service discovery, configuration management, circuit breakers, and distributed messaging. Spring Cloud builds on Spring Boot to create cloud-native applications.
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