15 Frequently Asked Spring Boot Interview Questions and Answers

Spring Boot simplifies the creation of production‑grade, stand‑alone Spring applications by providing auto‑configuration starters that eliminate the need for complex XML or manual setup, making Java development more efficient.

Key characteristics include rapid onboarding, zero‑configuration defaults, embedded servers, built‑in monitoring, and no code generation or XML requirements.

A XXXAutoConfiguration class defines conditional beans, while developers can also create custom starters to extend functionality.

The spring-boot-starter-parent sets Java 1.8 compatibility, UTF‑8 encoding, inherits dependency versions, configures packaging, resource filtering, plugin settings, and profile‑specific property handling.

YAML configuration offers ordered, array‑supporting, and concise syntax compared to traditional .properties, though it cannot be loaded via @PropertySource.

Cross‑origin issues are best solved on the backend with CORS annotations ( @CrossOrigin) rather than front‑end JSONP, which is limited to GET requests.

For security, Spring Security provides a heavyweight, feature‑rich framework, while Apache Shiro is lightweight and simpler to configure; the choice depends on project needs.

Session sharing across microservices can be achieved with Spring Session backed by Redis, storing all session data in a central store.

Hot deployment is enabled by adding the devtools dependency, which restarts the application on class changes, or by using LiveReload for template‑only updates.

Scheduled tasks are supported via Spring's @Scheduled annotation or the Quartz framework for more advanced job scheduling.

API documentation in a Spring Boot project is commonly generated with Swagger, which automatically updates the docs when the code changes.

Spring Data simplifies database access for both NoSQL (MongoDB, Neo4j, Redis, HBase) and relational stores (JDBC, JPA), reducing DAO boilerplate.

XML configuration is still possible using @ImportResource, though Java‑based configuration is preferred.

Spring Boot builds an executable JAR that runs via java -jar xxx.jar; this JAR differs from a regular JAR because the application classes reside under BOOT-INF/classes and cannot be directly used as a library without additional packaging.

When using Spring Cloud, bootstrap.properties loads before application.properties, allowing early configuration such as remote config servers.

The article concludes by inviting readers to share their own Spring Boot interview experiences.