Understanding Spring Boot Basics

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Spring Boot is a powerful framework designed to simplify the development of Java-based applications by eliminating boilerplate code and configurations. It builds on top of the Spring Framework and enables developers to create production-ready applications quickly.

Why Use Spring Boot?

  • Auto-Configuration: Reduces manual configuration.
  • Embedded Servers: Comes with built-in Tomcat, Jetty, or Undertow.
  • Standalone Applications: No need to deploy on an external server.
  • Microservices-Friendly: Simplifies the development of microservices.
  • Spring Ecosystem: Integrates well with Spring Security, Spring Data, and other modules.

Key Features of Spring Boot

1. Spring Boot Starters

Spring Boot provides a set of pre-defined dependencies called starters that simplify project setup. For example:

  • spring-boot-starter-web – For web applications.
  • spring-boot-starter-data-jpa – For working with databases using JPA.
  • spring-boot-starter-security – For integrating Spring Security.

2. Spring Boot Auto-Configuration

Spring Boot automatically configures beans based on classpath settings. For example, if spring-boot-starter-web is present, it configures an embedded web server and required components.

3. Spring Boot Annotations

Spring Boot uses various annotations to simplify development:

  • @SpringBootApplication – Marks the main class as a Spring Boot application.
  • @RestController – Used for building RESTful APIs.
  • @RequestMapping – Maps web requests to handler methods.
  • @Autowired – Enables dependency injection.

4. Embedded Web Server

Spring Boot includes an embedded web server (Tomcat by default), allowing applications to run independently without needing external deployment.

5. Spring Boot Application Properties

Configuration is done via application.properties or application.yml. Example:

server.port=8081
spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=root
spring.datasource.password=secret

Creating a Simple Spring Boot Application

Step 1: Set Up Spring Boot Project

Use Spring Initializr (https://start.spring.io/) to generate a Spring Boot project with dependencies like Spring Web.

Step 2: Create the Main Application Class

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

Step 3: Create a REST Controller

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class HelloController {
    @GetMapping("/hello")
    public String sayHello() {
        return "Hello, Spring Boot!";
    }
}

Running the Application

Run the main class, and access the REST API at http://localhost:8080/api/hello.

Conclusion

Spring Boot simplifies Java development by providing auto-configuration, embedded servers, and easy integration with Spring components. Whether building monolithic applications or microservices, Spring Boot offers a solid foundation for Java developers.

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