Spring Boot: Top 5 Interview Questions and answers for Experienced

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 Question 1: What is Spring Boot, and how does it differ from the traditional Spring framework?

Answer: Spring Boot is an extension of the Spring framework that simplifies the process of building and deploying production-ready applications. It provides a set of conventions, auto-configuration, and tools to streamline application development. The key difference between Spring Boot and the traditional Spring framework is that Spring Boot removes much of the manual configuration that is typically required in Spring applications, making it easier to set up and start a project. It also includes an embedded application server (like Tomcat, Jetty, or Undertow) for easy deployment.

Example code if required:

java
// Traditional Spring Application Configuration
@Configuration
@EnableWebMvc
public class MyApplicationConfig extends WebMvcConfigurerAdapter {
    // Configuration code here
}

// Equivalent Spring Boot Configuration
@SpringBootApplication
public class MyApplication {
    public static void main(String[] args) {
        SpringApplication.run(MyApplication.class, args);
    }
}

Question 2: What is Spring Boot Auto-Configuration, and how does it work?

Answer: Spring Boot Auto-Configuration is a feature that automatically configures the Spring application context based on the dependencies present in the project. It scans the classpath for specific libraries and provides sensible defaults for various components, such as data sources, security, and messaging. If a specific configuration is needed, developers can override or customize it. Auto-Configuration simplifies the development process by reducing the need for extensive configuration files.

Question 3: How does Spring Boot handle externalized configuration?

Answer: Spring Boot supports externalized configuration through properties files (application.properties or application.yml). It allows you to define configuration properties outside your application code and change them without modifying the application. Spring Boot provides a wide range of options for property configuration, including profiles, environment-specific properties, and the ability to override values using command-line arguments, environment variables, or configuration files.

Example code if required:

yaml
# application.properties
server.port=8080
spring.datasource.url=jdbc:mysql://localhost/mydb

Question 4: Explain Spring Boot's embedded container support. What containers are supported?

Answer: Spring Boot includes support for embedded containers like Tomcat, Jetty, and Undertow, which can be used for deploying web applications. These containers are included as dependencies, and Spring Boot auto-configures them based on your project's needs. Developers don't need to set up an external container separately, making it easier to package and run Spring Boot applications.

Question 5: What is Spring Boot Actuator, and how can it be used for monitoring and managing applications?

Answer: Spring Boot Actuator is a set of production-ready features that help you monitor and manage your Spring Boot application. It provides endpoints that expose information about your application, such as health, metrics, environment properties, and more. Actuator endpoints can be used for monitoring and diagnostics in a production environment. They are typically secured and can be customized to expose only the information needed.

Example code if required: To enable Spring Boot Actuator, add the following dependency to your project:

xml
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>