Java Spring Boot is a widely used framework for building enterprise-grade applications. It simplifies the bootstrapping and development of a Spring application. If you're preparing for a job interview related to Java Spring Boot, this blog post will guide you through some of the most common interview questions.
For Beginners
- What is Spring Boot? Spring Boot is a framework from the team at Pivotal, designed to simplify the bootstrapping and development of a new Spring application. The framework takes an opinionated approach to configuration, freeing developers from the need to define boilerplate configuration.
- What are the advantages of using Spring Boot? Spring Boot offers a number of advantages: it simplifies Spring dependencies by taking a commonsense approach to their configuration, it includes embedded Tomcat, Jetty, or Undertow directly, no need to deploy WAR files, it provides opinionated 'starter' dependencies to simplify your build configuration and it automatically configures Spring whenever possible.
- What is a Spring Boot starter? A Spring Boot starter is a set of convenient dependency descriptors that you can include in your application. Starters contain a lot of the dependencies you need to get a project up and running quickly and with a consistent, supported set of managed transitive dependencies.
- How can you create a Spring Boot application? You can create a Spring Boot application by using Spring Initializr, Spring Boot CLI, or manually initializing a new project with your preferred build system and importing the Spring Boot starter dependencies.
- What is the use of the `@SpringBootApplication` annotation? The `@SpringBootApplication` annotation is a convenience annotation that adds all of the following: `@Configuration`: Tags the class as a source of bean definitions for the application context. `@EnableAutoConfiguration`: Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings. `@ComponentScan`: Tells Spring to look for other components, configurations, and services in the package where the application is located.
- What is the Spring Boot auto-configuration? Auto-configuration is a feature in Spring Boot that automatically configures your Spring application based on the JAR dependencies that you added in the project.
- What is the Spring Boot Actuator? Spring Boot Actuator is a sub-project of Spring Boot. It adds several production grade services to your application with little effort on your part.
- What embedded containers does Spring Boot support? Spring Boot supports Tomcat (default), Jetty, and Undertow as embedded servlet containers.
- What are the Spring Boot DevTools? Spring Boot includes an additional set of tools that can make the application development experience a little more pleasant. The spring-boot-devtools module can be included in any project to provide additional development-time features.
- What is the difference between an embedded container and a WAR? An embedded container is a container that's included as part of your application. A WAR file is a Web Application Archive file that is used to distribute a collection of JavaServer Pages, Java Servlets, Java classes, XML files, tag libraries, static web pages (HTML and related files) and other resources that together constitute a web application.
For Advanced Developers
- How does Spring Boot handle database migrations? Spring Boot can manage database migrations using a tool called Flyway. Flyway is an open-source database migration tool that strongly favors simplicity and convention over configuration.
- What is Actuator in Spring Boot? Spring Boot Actuator provides production-ready features for monitoring our application, gathering metrics, understanding traffic, or the state of our database.
- How does Spring Boot handle security? Spring Boot uses Spring Security, a powerful and highly customizable authentication and access-control framework. It is the de-facto standard for securing Spring-based applications.
- What is Thymeleaf in Spring Boot? Thymeleaf is a Java-based library used to create a web application. It provides an optional integration with Spring MVC and Spring Boot.
- How can you customize the Spring Boot banner? The Spring Boot banner can be customized by adding a `banner.txt` file to your classpath or by setting the `spring.banner.location` property to the location of such a file.
- What is the use of Profiles in Spring Boot? Spring Profiles provide a way to segregate parts of your application configuration and make it available only in certain environments.
- How to handle exceptions in Spring Boot? Spring Boot provides a `@ControllerAdvice` annotation that we can use with any class to define our global exception handler.
- What is a Spring Boot Fat JAR? A Spring Boot fat JAR is a JAR file that contains all the dependencies required for a Spring Boot application to run. The term "fat" refers to the size of the JAR file, as it is significantly larger than a regular JAR file.
- What is YAML in Spring Boot? YAML, or YAML Ain't Markup Language, is a human-friendly data serialization standard for all programming languages. Spring Boot uses YAML as one of the formats for storing configurations.
- How to enable HTTPS in Spring Boot? To enable HTTPS in Spring Boot, you need to modify the application.properties file and include your keystore file in your classpath.
Remember, the key to acing an interview is understanding the core concepts and practicing. Good luck with your interview preparation!