What is Spring Boot?

Spring Boot is built on top of the Spring Framework and provides a simplified way to set up, configure, and run both simple and web-based applications. It follows the convention-over-configuration approach, which reduces the boilerplate code needed to set up a Spring application. With Spring Boot, you can create a standalone application that you can "just run" without needing to deploy it to an application server.

• Auto-configuration: Automatically configures Spring application based on dependencies • Standalone: Creates standalone Spring applications • Opinionated: Provides opinionated 'starter' dependencies to simplify build configuration • Production-ready: Includes features like health checks, metrics, and externalized configuration • No XML: No requirement for XML configuration

Here's a simple Spring Boot application that starts a web server:

@SpringBootApplication
public class HelloWorldApplication {

    public static void main(String[] args) {
        SpringApplication.run(HelloWorldApplication.class, args);
    }
}

@RestController
class HelloController {

    @GetMapping("/")
    public String hello() {
        return "Hello, Spring Boot!";
    }
}