Difference between Spring and Spring Boot

Question

There are many people who advised me to use Spring Boot instead of Spring to develop REST web services. I want to know what exactly the difference between the two is?

Answer 1

Spring Boot is opinionated view of Spring Framework projects.Let's analyse it through one program taken from Spring Boot Documentation.

@RestController
@EnableAutoConfiguration
public class Example {

    @RequestMapping("/")
    String home() {
        return "Hello World!";
    }

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

It's a very basic REST API and you need to add Spring-boot-starter-web in your POM.xml for the same. Since you have added starter-web dependency, the annotation @EnableAutoConfiguration guesses that you want to develop a web application and sets up Spring accordingly.

Spring Boot auto-configuration attempts to automatically configure your Spring application based on the jar dependencies that you have added. For example, if HSQLDB is on your classpath, and you have not manually configured any database connection beans, then Spring Boot auto-configures an in-memory database.

It's opinionated like maven. Maven creates a project structure for you which it thinks is the general pattern of projects like it adds src/main/java folder or resource folder for you.

Spring boot helps in faster development. It has many starter projects that helps you get going quite faster. It also includes many non functional features like: embedded servers, security, metrics, health checks etc. In short, it makes, spring based application development easier with minimally invading code(Less configuration files, less no of annotations).

Reference: https://docs.spring.io/spring-boot/docs/current-SNAPSHOT/reference/htmlsingle/#boot-documentation-about